METTLER TOLEDO TItrators
Toluene
OIL
Glue
Karl Fischer Applications
Chemicals, Solvents, Petroleum Products, Plastics
Karl Fischer Water Content Determination
in Chemicals, Solvents, Petroleum Products and Plastics
Contents 1. Introduction
4
2. Inorganic raw materials
5
3. Organic raw materials
9
4. Solvents
15
5. Petroleum products
21
6. Plastics and adhesives
27
7. Medicines (pharmaceuticals)
31
8. Dyes and agrochemicals
35
9. Detergents and surfactants
38
10. Silk, wool, cellulose, paper and wood
40
11. Building materials and minerals
42
12. Index of reagents and suppliers
44
13. KF reagent hazards and waste disposal tips
46
14. Sample Index
47
References Fischer, K., Angew. Chem. 48, 394 (1935)
Mitchell Jr., J. and Smith, D.M., „Aquametry“ Part III, Second edition,
John Wiley and Sons, Inc., New York, 1980
Riedel-de Haën, HYDRANAL® Manual
Fifth edition, 1988
Scholz, E., Karl Fischer Titration,
Springer Verlag, Berlin, 1984
Wieland, G., Wasserbestimmung durch Karl-Fischer-Titration,
GIT Verlag GmbH, Darmstadt, 1985
METTLER, Karl Fischer Applications
3
1. Introduction
The quality and often the usability of many raw materials, intermediates and substances necessary for the manufacturing of high-grade products frequently depend decisively on the water content. Securing and optimizing the product quality
thus necessitates regular control of the water content.
Karl Fischer titration, being efficient, rapid and accurate, is the most important
method for determining water contents. Thanks to its selectivity, the method fulfills
todays requirements. The traditional drying oven technique, in contrast, has
many systematic errors, is inefficient and slow.
The method developed by Karl Fischer, in which water is titrated in the presence
of sulfur dioxide and an organic base [1], was improved significantly by
E. Eberius, J.C. Verhoef and E. Scholz [2].
2 H20 + S02 + I2 —> H2S04 + 2 Hl
[1]
H20 + I2 + S02 + CH30H + 3 RN —> [RNH]S04CH3 + 2 [RNH]I [2]
In an initial reaction, sulfur dioxide, methanol and the base have recently been
shown to react to form methyl sulfite [RNH]SO3CH3.
The pyridine used initially by Karl Fischer has been replaced by more suitable
amines. Several companies supply pyridine-free Karl Fischer reagents with a
constant titer.
Microprocessor controlled METTLER DL18 and DL35 Karl Fischer titrators as well
as METTLER DL37 KF Coulometer allow water contents to be determined rapidly,
easily and reproducibly. The DL35 and DL18 are recommended for water contents ranging from ppm to 100%, whereas the DL37 is useful for trace moisture
content determinations.
Karl Fischer titration allows the quantification of freely available water which has
been brought into solution prior to the titration using an appropriate method.
Gases and liquids are generally easily dissolved in methanol, the usual solvent
for Karl Fischer titration.
Solids, however, may contain water as water of crystallization, occluded water or
as adherent moisture. For this reason, sample preparation is most important for
the analysis. A total water content determination requires that the sample be completely dissolved. Should this not be possible in methanol, it may be necessary to
add decanol, chloroform, formamide or other solvents. In certain instances titration at elevated temperatures, at the boiling point, or after external extraction may
be helpful.
For thermally stable products, such as polymers, evaporation of the moisture in a
drying oven (METTLER DO302 or DO337) and transferring the vapor into the
titration cell by a dry purge gas is recommended.
The differential availability of the water may be used to selectively quantify only
the adherent moisture (for plastics, for instance). It is, however, necessary to prevent the rediffusion of more water.
Undesirable side reactions of the KF reagents, such as esterification or bisulfite
addition, may be prevented by the proper selection of reactant composition and
measurement conditions.
4
METTLER, Karl Fischer Applications
2. Inorganic raw materials
General comments Salts
Salts can contain water in the following ways: water of crystallization, included water and adherent moisture.
In order to quantify water of crystallization and included water, the sample
must be dissolved completely. Methanol is usually a suitable solvent.
Some substances may require the addition of formamide, or titration at elevated temperatures. For substances that dissolve slowly, finely crushing the
sample may be helpful.
When determining only the adherent moisture, dissolution of the substance
and diffusion of other water into the titration must be prevented. For this
reason, a high proportion of chloroform is used in the solvent.
Acids and bases
These must be neutralized prior to the titration. Imidazole or pyridine are
used for acids, benzoic acid or salicylic acid for bases.
Strong acids also tend to undergo esterification, whereby water is formed
(for example highly concentrated acids such as gaseous HCl or H2SO4
96%).
The following inorganic compounds react with Karl Fischer reagents in a
side reaction which leads to an incorrect water content:
peroxides, oxides, hydroxides, carbonates, hydrogen carbonates, disulfites,
nitrites, sulfites, thiosulfates, hydrazine and derivatives, iron(III) salts,
copper(I) salts, tin(II) salts, silanols, arsenites, arsenates, selenites, tellurites and boron compounds.
For these compounds a direct KF titration is not suitable. The moisture from
thermally stable compounds should be evaporated in a drying oven and
the moisture transferred into the titration cell with a dry purge gas. External
extraction may also be used; however, the sample must be insoluble in the
extraction solvent.
References: ISO 3699-1976 Anhydrous Hydrogen Fluoride for Industrial Use – Determination of Water Content – Karl Fischer Method
ISO/DIS 7105 Liquified Anhydrous Ammonia for Industrial Use – Determination of Water Content – Karl Fischer Method
Bryant, W.M.D. and Mitchell, J., Analytical Procedures Employing Karl
Fischer Reagent (Determination of Water of Hydration in Salts in Inorganic
Oxides and Related Components), J. Am. Chem. Soc. 63, 2924-2930
(1941)
METTLER, Karl Fischer Applications
5
Applications: Inorganic raw materials
A) Volumetric determination using DL35
Sample
Weight
Result
g
n %
RSD
%
Titrant
Solvent
Method
CaCl2 • 2H2O
0.1
6
26.4
0.46
Composite 5
30 mL methanol
Sample input: weighing boat
Stir time: 50 s
Phosphoric acid 0.15
6
13.7
0.5
Titrant 5
30 mL solvent
20 mL buffer
Sample input: syringe with needle
Stir time: none
Sulfuric acid
approx. 96%
0.1
6
4.63
1.4
Titrant 5
30 mL solvent
20 mL buffer
Sample input: syringe with needle
Stir time: none
Sodium
carbonate
1.7
6
0.443
3.2
Composite 2
40 mL methanol
Evaporate moisture with drying oven
DO302: 250 °C, 200 mL N2/min
Stir time: 700 s
Calcium oxide
1.5
5
0.227
10.9
Composite 2
40 mL methanol
Evaporate moisture with drying oven
DO302: 250 °C, 200 mL N2/min
Stir time: 600 s
Aluminum oxide 1.3
6
0.148
2.2
Titrant 2NH
30 mL solvent
Sample input: weighing boat
Stir time: 300 s
Reagents:
Titrant 2NH:
Titrant 5:
Solvent:
Composite 2:
Composite 5:
Buffer:
two component reagent HYDRANAL® Titrant 2NH, Riedel No. 34811 (titrant)
two component reagent HYDRANAL® Titrant 5, Riedel No. 34801 (titrant)
two component reagent HYDRANAL® Solvent, Riedel No. 34800 (solvent)
one component reagent HYDRANAL® Composite 2, Riedel No. 34806 (titrant)
one component reagent HYDRANAL® Composite 5, Riedel No. 34805 (titrant)
buffer 5mmol acid/mL HYDRANAL® Buffer, Riedel No. 34804
B) Coulometric determination using DL37
Sample
Weight
Result
g
n %
RSD
%
Reagents
Magnesium
oxide
0.07
5 4.6
2.4
100 mL Coulomat A Evaporate moisture with drying oven
5 mL Coulomat C
DO337: 250 °C, 200 mL air/min
Titration time: 400 s
Sodium chloride 1.0
5 0.0360
4.2
100 mL Coulomat A Evaporate moisture with drying oven
5 mL Coulomat C
DO337: 300 °C, 200 mL air/min
Titration time: 600 s
Lithium chloride 1.0
5 0.7088
3.4
100 mL Coulomat A Evaporate moisture with drying oven
5 mL Coulomat C
DO337: 250 °C, 200 mL air/min
Titration time: 600 s
Aluminum
powder
6 0.0212
3.4
100 mL Coulomat A Evaporate moisture with drying oven
5 mL Coulomat C
DO337: 280 °C, 200 mL air/min
Titration time: 900 s
3.0
Method
Titration parameters for titrations with drying oven DO337:
Adjustment: control gain: 5; switch-off criterium: fixed titration time
automatic drift determination, manual titration start
Reagents:
Coulomat A:
Coulomat C:
6
anode reagent HYDRANAL® Coulomat A, Riedel No. 34807
cathode reagent HYDRANAL® Coulomat C, Riedel No. 34808
METTLER, Karl Fischer Applications
Comments concerning applications using DL35
Calcium chloride The sample is slightly hygroscopic. All 6 samples could be titrated in the
indicated amount of solvent.
Phosphoric acid The direct titration is unproblematic. The sample must be neutralized with a
base (such as imidazole), otherwise the endpoint will be sluggish.
Sulfuric acid The sample is hygroscopic. The plastic syringe must be discarded after
approx. 96% 3 samples, as the acid will attack it.
Neutralization of the sample with a base (i.e., imidazole) is necessary.
Sodium carbonate Carbonate reduces iodine to give iodide, which results in an erroneously
high water content.
Na2CO3 + I2 + SO2 + CH3OH –> 2NaI + CO2 + HSO4CH3
For this reason the drying oven is used.
An external extraction with methanol results in values that are too high,
since sodium carbonate is slightly soluble in methanol.
Calcium oxide The KF solutions are always weakly acidic, thus they may react with oxides
in a reaction that produces water. CaO + 2 HI –> CaI2 + H2O
This is why use of the drying oven is recommended.
An external extraction with methanol results in elevated values, as traces of
calcium oxide will dissolve in methanol.
Aluminum oxide Aluminum oxide is not basic enough to react with the KF solution. Direct
titration is possible. The sample is highly hygroscopic, thus contact with the
ambient is to be held at a minimum.
The sample releases water slowly, therefore it is necessary to stir for
5 minutes.
Comments concerning applications using DL37
Many inorganic salts have low water contents and are thermally stable.
For this reason a coulometric determination using a drying oven is an ideal
method.
Magnesium oxide The high water content necessitates a small sample. This in turn requires
that the sample be homogeneous in order to get reproducible results.
Sodium chloride, The coulometric determination using the drying oven is unproblematic.
lithium chloride,
aluminum powder
METTLER, Karl Fischer Applications
7
Karl Fischer Titration
Water Content Determination of Inorganic Solids
Sample: 3 g Aluminum powder
Preparation:
Heat sample in a crucible, evaporate
the moisture and transfer the vapor into
the titration cell by a dry purge gas.
Oven temperature: 280 °C
Purge gas:
200 mL air/minute
Method:
Sample Input:
Fill sample from weighing boat through
connection piece into the crucible.
Cathode Solution:
5 mL Catholyte
(HYDRANAL® Coulomat C No. 34808)
Anode Solution:
100 mL Anolyte
(HYDRANAL® Coulomat A No. 34807)
Comments:
Titration time: 15 minutes
The time required for evaporation of the
water is preferably entered as a fixed
titration time (parameter L.Time).
See the operating instructions of the
drying oven for instructions regarding
its use.
Result und Statistics:
Application:
Chemical industry
Instruments:
METTLER DL37 KF Coulometer
Drying oven METTLER DO337
A. Aichert, Application Laboratory, Nov. 1990
8
METTLER, Karl Fischer Applications
3. Organic Raw Materials
General comments
Hydrocarbons, halogenated hydrocarbons, alcohols, esters and ether
The water content determination of these substances is unproblematic.
Adding propanol or chloroform increases the solubility of long chained
compounds. Double bonds rarely cause problems.
These compounds generally contain little water, thus coulometry is particularly recommended. Halogenated hydrocarbons may contain active
chlorine from the production process. The active chlorine oxidizes iodide to
iodine (resulting in an erroneously low water content).
Phenols
For most phenols the water content determination is unproblematic. In
some cases salicylic acid may need to be added as a buffer. Some phenols
have been shown to have a high post-consumption (for example, aminophenol).
Aldehydes and ketones
These compounds react with methanol to produce acetals and ketals respectively. Water is produced in the reactions. These side reactions may be
suppressed by using methanol-free titrants and solvents. Special reagents
for the water content determination of aldehydes and ketones are available.
Bisulfite addition is a further side reaction which aldehydes will undergo.
This reaction consumes water and starts as soon as the sample is added to
the solvent containing sulfur dioxide. The titration must thus be started immediately to circumvent the bisufite addition.
Organic acids
Strongly acidic organic acids should be neutralized to keep the pH value in
the proper range for a KF titration.
Nitrogen compounds
Strongly basic amines are neutralized with benzoic acid. The solubility of
higher amines needs to be improved by adding chloroform.
A few amines titrated with methanol as the solvent show an unstable endpoint (such as aniline, toluidine, aminophenol), probably due to a side
reaction. This can be eliminated by using a methanol-free solvent.
The water content determination of hydroxylamine, hydrazine and hydrazine salts is difficult. Their oxidation by iodine results in erroneously high
water contents.
Sulfur compounds
The determination of these compounds is unproblematic. Exceptions are
mercaptans and thiols. These are oxidized by iodine, resulting in erroneously high water contents.
References
Scholz, E., Wasserbestimmung in Carbonsäuren,
Fresenius Z. Anal. Chem. 312, 423-426 (1982)
Scholz, E., Titration of Aldehydes and Ketones
Anal. Chem. 57, 2965-2971 (1985)
Scholz, E., Wasserbestimmung in Phenolen
Fresenius Z. Anal. Chem. 330, 8, 694-697 (1988)
METTLER, Karl Fischer Applications
9
Applications: Organic raw materials
A) Volumetric determination using DL35
Sample
Weight
Result
g
n %
RSD
%
Titrant
Solvent
Method
4-Chlorotoluene 2.5
8 0.0089
2.3
Composite 2
30 mL methanol
Input: syringe with needle
Stir time: none
Benzyl alcohol
2.5
7 0.137
0.57
Composite 2
30 mL methanol
Input: syringe with needle
Stir time: none
2-Nitrophenol
2.0
6 0.0549
1.9
Titrant 2NH
30 mL solvent
10 mL buffer
Crush sample in mortar
Input: weighing boat
Stir time: 30 s
Acetophenone
2.0
8 0.524
0.41
Composite 5K
30 mL
Working medium K
Input: syringe with needle
Stir time: none
Benzaldehyde
1.0
8 0.168
0.32
Composite 5K
30 mL
Working medium K
Input: syringe with needle
Stir time: none
Start titration immediately
Salicylic acid
1.0
6 0.0140
0.8
Composite 2
30 mL methanol
External dissolution in methanol:
dissolve 30 g in 60 mL MeOH,
Input: 3 ml aliquot with syringe
Oxalic acid
0.06
6 27.9
0.43
Titrant 5
20 mL solvent
20 mL buffer
Input: weighing boat
Stir time: 300 s
Methyl benzoate 3.0
6 0.0083
2.8
Composite 1
30 mL methanol
Input: syringe with needle
Stir time: none
Urea
2.0
6 0.123
4.4
Composite 2
30 mL methanol
Input: weighing boat
Stir time: none
n-Butylamine
0.5
7 1.12
0.4
Titrant 2NH
30 mL solvent
4 g benzoic acid
Input: syringe with needle
Stir time: none
Aniline
2.5
6 0.0819
2.7
Composite 5K
30 mL
Working medium K
5 g salicylic acid
Input: syringe with needle
Stir time: none
Reagents:
Titrant 2NH:
Solvent:
Composite 1:
Composite 2:
Composite 5:
Composite 5K:
Working medium K:
Buffer:
10
two component reagent HYDRANAL® Titrant 2NH, Riedel No. 34811 (titrant)
two component reagent HYDRANAL® Solvent, Riedel No. 34800 (solvent)
one component reagent HYDRANAL® Composite 1, Riedel No. 34827 (titrant)
one component reagent HYDRANAL® Composite 2, Riedel No. 34806 (titrant)
one component reagent HYDRANAL® Composite 5, Riedel No. 34805 (titrant)
one component reagent HYDRANAL® Composite 5K, Riedel No. 34816
(Titrant for aldehydes and ketones)
one component reagent HYDRANAL® Working Medium K, Riedel No. 34817
(Solvent for aldehydes and ketones)
buffer 5mmol acid/mL HYDRANAL® Buffer, Riedel No. 34804
METTLER, Karl Fischer Applications
Comments concerning applications with DL35
4-Chlorotoluene, The direct titration is unproblematic. A titrant with a low concentration
benzyl alcohol (2 mg H2O/mL) is used due to the low water content.
2-Nitrophenol The sample crushed in the mortar dissolves easily in the solvent. Without a
buffer an elevated post-consumption is observed.
Acetophenone Ketones react with methanol to give ketals and water. To prevent this, a
methanol-free titrant and solvent are used.
The solvent should be changed after 4 samples.
Benzaldehyde Aldehydes react with methanol to form an acetal and water. To prevent this,
a methanol-free titrant and solvent should be used. A further side reaction is
bisulfite addition, which consumes water. For this reason the titration is
started immediately after injecting the sample. The weight is entered on the
titrator after the titration.
The solvent must be replaced after each sample. When performing several
titrations in the same solvent a decrease in the determined water content is
observed.
Salicylic acid Finely pulverized salicylic acid may become electrostatically charged,
causing problems during transfer of the sample into the titration cell. The
titration cell remains open for different lengths of time. This may lead to
considerable scatter of the results when titrating small quantities of water.
For this reason, external dissolution in methanol is used. This solution must
be analyzed immediately, as an increasing amount of water (i.e., 250 ppm
after 24 h) is determined after the solution has been standing for some time
(over 3 hours). The cause is a slow esterification of the acid.
Oxalic acid The solvent is to be replaced after 2 samples as its buffering capacity will
be exhausted.
Methyl benzoate The direct titration is straightforward. Due to the low water content, a titrant
with the concentration of 1 mg H2O/ml was used.
Urea As urea is slightly soluble in methanol, the solvent must be replaced after
each sample.
n-Butylamine The endpoint is sluggish in spite of the neutralization with benzoic acid.
The results are too high and poorly reproducible. Decreasing the switch-off
delay to 7 seconds allows reliable and reproducible results to be obtained.
Aniline No stable endpoint could be achieved using methanol as the solvent. Using
a methanol-free solvent eliminates this problem. Neutralizing the aniline
with salicylic acid is necessary, otherwise the endpoint will be sluggish.
METTLER, Karl Fischer Applications
11
Applications: Organic raw materials
B) Coulometric determination using DL37
Sample
Weight
Result
g
n ppm
RSD
%
Reagents
Method
Naphtaline
0.1
6 35.0
10.2
100 mL Coulomat A
5 mL Coulomat C
external dissolution in MeOH:
dissolve 0.4 g in 25 mL MeOH
Input: 5 mL aliquot with syringe
Stir/Titration time: 0/40 s
4-Chlorotoluene 0.8
dried (1)
6 30.7
1.7
100 mL Coulomat A
5 mL Coulomat C
Input: syringe with needle
Stir/Titration time: 0/40 s
Benzylalcohol
dried (1)
0.4
6 1273
0.16
100 mL Coulomat A
5 mL Coulomat C
Input: syringe with needle
Stir/Titration time: 0/80 s
Phenol
1.0
6 173.7
1.8
100 mL Coulomat A
5 mL Coulomat C
external dissolution in MeOH:
dissolve 17 g in 60 mL MeOH
Input: 1 mL aliquot with syringe
Stir/Titration time: 0/70 s
Acetophenone
dried (1)
0.3
6 2830
0.46
100 mL Coulomat AK Input: syringe with needle
5 mL Coulomat CK
Stir/Titration time: 0/120 s
Benzaldehyde
dried (1)
0.4
6 242.6
0.9
100 mL Coulomat AK Input: syringe with needle
5 mL Coulomat CK
Stir/Titration time: 0/90 s
Salicylic acid
0.4
6 115.8
2.9
100 mL Coulomat A
5 mL Coulomat C
external dissolution in MeOH:
dissolve 30 g in 60 mL MeOH
(titrate immediately)
Input: 3 mL aliquot with syringe
Stir/Titration time: 0/50 s
Methylbenzoate
dried (1)
0.9
6 49.1
2.0
100 mL Coulomat A
5 mL Coulomat C
Input: syringe with needle
Stir/Titration time: 0/120 s
Benzamide
0.3
6 117.5
3.6
100 mL Coulomat A
5 mL Coulomat C
External dissolution in MeOH:
dissolve 16 g in 50 mL MeOH
Input: 1 mL aliquot with syringe
Stir/Titration time: 0/50 s
n-Butylamine
0.2
6 1.14%
0.8
100 mL Coulomat A
20 g benzoic acid
5 mL Coulomat C
Input: syringe with needle
Stir/Titration time: 0/200 s
Aniline
0.1
1 No result
100 mL Coulomat AK Input: syringe with needle
20 g benzoic acid
5 mL Coulomat CK
Standard titration parameters for all titrations:
Adjustment: control gain: 5 switch-off criterium: End level 0.1 µg/s (0.1 µg H2O/s above drift value)
automatic drift determination, automatic titration start
(1) Dried over molecular sieve 3Å
Reagents:
Coulomat A:
Coulomat C:
Coulomat AK:
Coulomat CK:
12
anode reagent HYDRANAL® Coulomat A, Riedel No. 34807
cathode reagent HYDRANAL® Coulomat C, Riedel No. 34808
anode reagent HYDRANAL® Coulomat AK, Riedel No.34820
cathode reagent HYDRANAL® Coulomat CK, Riedel No.34821
METTLER, Karl Fischer Applications
Comments concerning the applications with DL37
Naphtaline A small weigh-in is needed, as napthaline is poorly soluble in methanol.
The coulometric determination with external dissolution is unproblematic.
4-Chlorotoluene, The coulometric determination is straightforward.
benzyl alcohol,
methyl benzoate
Phenol Phenol is first dissolved externally in methanol.
Acetophenone Ketones react with methanol to form a ketal and water. To prevent this, a
methanol-free anolyte and catholyte are used.
With these reagents the titration of acetophenone is straightforward and
gives reproducible results.
Benzaldehyde Aldehydes react with methanol to give an acetal and water. To circumvent
this, methanol-free anolyte and catholyte solutions are used. A further side
reaction is bisulfite addition, a process in which water is consumed.
The titration is started using AUTOSTART immediately after sample addition.
The sample weight is entered on the DL37 during or after the titration.
Salicylic acid and Salicylic acid and benzamide are dissolved in methanol and the external
benzamide solution is then titrated. The salicylic acid solution must be analyzed immediately, since the water content increases upon standing for over 3 hours
(for example, 250 ppm after 24 hours). The slow esterification of the acid
is the cause.
n-Butylamine This is titrated coulometrically by adding benzoic acid. The determined
values tend to increase within the series, resulting in a decreasing reproducibility.
Aniline Aniline will not give a stable endpoint using methanol as the solvent. Even
after using methanol-free reagents and after neutralizing the aniline with
salicylic acid, a coulometric titration proved to be impossible (no endpoint).
METTLER, Karl Fischer Applications
13
Karl Fischer Titratrion
Water Content Determination of Organic Solids
Sample: 0.3 g Phenol
Preparation:
17 g phenol are dissolved in 47 g
methanol in a bottle sealed with a septum. 1 mL aliquots of the solution are
taken with a syringe for the titration.
Determine the water content of the methanol and enter this as Parameter A.
Method:
Sample Input:
Syringe with needle
(such as ME-71482)
Catholyte:
5 mL Catholyte
(HYDRANAL® Coulomat C, No. 34808)
Anolyte:
100 mL Anolyte
(HYDRANAL® Coulomat A, No. 34807)
Result and Statistics:
Comments:
Titration time: 70 seconds
For the coulometric water content determination of solids, an external extraction or external dissolution must be
used. Adding solids directly into the
titration cell by opening the stopper
results in erroneously high water contents (variance greater than 50%).
The DL37 has special calculation formulas for external extraction and external dissolution. The parameters are:
A
water content of the solvent
(ppm)
B
total solvent amount (g)
WtO amount of sample dissolved in B
solvent
Net Aliquot amount (g)
Application:
Chemistry, plastics, pharmaceuticals
Instruments:
METTLER DL37 KF Coulometer
A. Aichert, Application Laboratory, Nov. 1990
14
METTLER, Karl Fischer Applications
4. Solvents
Toluene
General comments Hydrocarbons, halogenated hydrocarbons, alcohols, esters and ether
The water content determination of these substances is unproblematic.
Adding propanol or chloroform increases the solubility of long chained
compounds. Double bonds rarely cause problems.
These compounds generally contain little water, thus coulometry is particularly recommended. Halogenated hydrocarbons may contain active
chlorine from the production process. The active chlorine oxidizes iodide to
iodine (resulting in an erroneously low water content).
Phenols
For most phenols the water content determination is unproblematic. In
some cases salicylic acid may need to be added as a buffer. Some phenols
have been shown to have a high post-consumption (for example, aminophenol).
Aldehydes and ketones
These compounds react with methanol and produce acetals and ketals,
respectively. Water is produced in the reactions. These side reactions may
be suppressed by using methanol-free titrants and solvents. Special reagents for the water content determination of aldehydes and ketones are
available.
Bisulfite addition is a further side reaction which aldehydes will undergo.
This reaction consumes water and starts as soon as the sample is added to
the solvent containing sulfur dioxide. The titration must thus be started immediately to prevent the bisulfite addition.
Organic acids
Strongly acidic organic acids should be neutralized to keep the pH value in
the proper range for a KF titration.
Nitrogen compounds
Nitrogen-containing solvents such as amides (i.e., dimethylformamide),
nitro compounds (such as nitrobenzene), and nitriles (acetonitrile) are unproblematic.
References Scholz, E., Titration of Aldehydes and Ketones
Anal. Chem. 57, 2965-2971 (1985)
ISSN 0192-2971, ASTM Standard, D-1364-87, 1987
Test method for water in volatile solvents (Karl Fischer Titration)
METTLER, Karl Fischer Applications
15
Applications: Solvents
A) Volumetric determination using DL35
Sample
Weight
Result
g
n %
RSD
%
Titrant
Solvent
Method
Toluene
3.0
6 0.0144
0.37
Composite 2
30 mL methanol
Input: syringe with needle
Stir time: none
Cyclohexene
2.5
7 0.0080
1.5
Composite 1
30 mL methanol
Input: syringe with needle
Stir time: none
iso-Amyl alcohol 2.0
6 0.141
0.25
Composite 2
30 mL methanol
Input: syringe with needle
Stir time: none
Ethylen glycol
2.0
6 0.651
0.24
Composite 2
30 mL methanol
Input: syringe with needle
Stir time: none
Methylene
chloride
3.0
6 0.0115
1.2
Composite 2
30 mLmethanol
Input: syringe with needle
Stir time: 60 s
Diethylether
1.5
6 0.0553
0.40
Composite 2
30 mL methanol
Input: syringe with needle
Stir time: none
Acetone
3.0
7 0.0128
0.48
Composite 5K
30 mL
Working medium K
Input: syringe with needle
Stir time: none
Isobutylmethylketone (IBMK)
1.5
6 0.145
0.39
Composite 5K
30 mL
Working medium K
Input: syringe with needle
Stir time: none
Formaldehyde
0.04
6 52.0
0.58
Titrant 5
30 mL solvent
20 mL buffer
Input: syringe with needle
Stir time: none
Acetaldehyde
1.3
6 0.0337
4.2
Composite 5K
30 mL
Working medium K
Cool sample to 0 °C
Input: syringe with needle
Titrate immediately
Acetic acid
1.0
6 0.263
0.24
Titrant 2NH
30 mL solvent
20 mL buffer
Input: syringe with needle
Stir time: none
Dimethylformamide (DMF)
1.5
7 0.0867
0.36
Titrant 2NH
20 mL solvent
20 mL buffer
Input: syringe with needle
Stir time: none
Acetonitrile
3.0
7 0.0128
2.3
Composite 2
30 mL methanol
Input: syringe with needle
Stir time: none
Reagents:
Titrant 2NH:
Solvent:
Composite 1:
Composite 2:
Composite 5:
Composite 5K:
Working medium K:
Buffer:
16
two component reagent HYDRANAL® Titrant 2NH, Riedel No. 34811 (titrant)
two component reagent HYDRANAL® Solvent, Riedel No. 34800 (solvent)
one component reagent HYDRANAL® Composite 1, Riedel No. 34827 (titrant)
one component reagent HYDRANAL® Composite 2, Riedel No. 34806 (titrant)
one component reagent HYDRANAL® Composite 5, Riedel No. 34805 (titrant)
one component reagent HYDRANAL® Composite 5K, Riedel No. 34816
(Titrant for aldehydes and ketones)
one component reagent HYDRANAL® Working Medium K, Riedel No. 34817
(Solvent for aldehydes and ketones)
buffer 5 mmol acid/mL HYDRANAL® Buffer, Riedel No. 34804
METTLER, Karl Fischer Applications
Comments concerning applications using DL35
Toluene, isoamyl- The direct titration is straightforward. Since the water content of these comalcohol, ethyleneglycol, pounds is low, a titrant with 2 mg H2O/mL is used.
methylene chloride,
diethylether
Cyclohexene A diluted titrant with a concentration of 1 mg H2O/mL is used to determine
the low water content of 80 ppm.
To achieve a good reproducibility of 1.5% RSD, the following points are
important:
– Condition syringe well with the sample
– Replace the solvent after each 3 samples
(The result using titrant 2 mg H2O/mL: RSD = 2.7% for 6 samples, sample
weight 2 g)
Acetone, Ketones react with methanol generating a ketal and water. Methanol-free
Isobutylmethylketone solvents and titrants must be used to prevent this.
Formaldehyde Formaldehyde will not react with methanol to form an acetal, thus methanol-containing reagents may be used.
The total water content cannot be determined by titrating at room temperature, as a part of the water is bound as paraformaldehyde.
Even at 50 °C, not all the water will be released (theoretical water content
= 55.8%).
Acetaldehyde Acetaldehyde boils at 15 °C. To simplify sample input with a syringe, cool
the sample to approx. 0 °C.
Acetal formation can be detected by the high post-comsumption, even
though methanol-free reagents were used. Reducing the switch-off delay to
7 seconds reduces the titration time and increases the reproducibility.
Additionally, the sample size was selected to be as small as possible and
was kept constant. The solvent was also renewed after each sample. Bisulfite addition occurs as a further side reaction. Water is consumed in this
reaction. To circumvent this problem, the titration is started immediately
after sample addition. The sample weight is entered on the titrator after the
titration.
Acetic acid Acetic acid has a slight tendency to esterify. Thus it is necessary to add a
buffer.
Dimethylformamide The Karl Fischer titration of DMF is straightforward. This is expected to be
true for amides of other carboxylic acids as well.
Acetonitrile The water content determination of acetonitrile is unproblematic.
METTLER, Karl Fischer Applications
17
Applications: Solvents
B) Coulometric determination using DL37
Sample
Weight
Result
g
n ppm
RSD
%
Reagents
Method
Toluene
dried (1)
3.0
6 4.8
9.8
100 mL Coulomat A
5 mL Coulomat C
Input: syringe with needle
Stir/Titration time: 0/60 s
n-Hexane
1.0
6 10.5
7.2
100 mL Coulomat A
5 mL Coulomat C
Input: syringe with needle
Stir/Titration time: 0/36 s
2.0
8 4.6
9.1
100 mL Anolyte
5 mL Catholyte
Input: syringe with needle
Stir/Titration time: 0/50 s
Cyclohexene
0.8
6 78.8
1.2
100 mL Coulomat A
5 mL Coulomat C
Input: syringe with needle
Stir/Titration time: 0/70 s
Isopropyl
alcohol
0.2
6 787.6
0.31
100 mL Coulomat A
5 mL Coulomat C
Input: syringe with needle
Stir/Titration time: 0/40 s
Ethylene
glycol
0.4
6 6541
0.56
100 mL Coulomat A
5 mL Coulomat C
Input: syringe with needle
Stir/Titration time: 0/440 s
Ethylene chloride 0.6
dried (1)
6 38.2
3.2
100 mL Coulomat A
5 mL Coulomat C
Input: syringe with needle
Stir/Titration time: 0/80 s
Diethylether
dried (1)
0.5
6 40.0
4.0
100 mL Coulomat A
5 mL Coulomat C
Input: syringe with needle
Stir/Titration time: 0/50 s
Acetaldehyde
0.5
1 no result
Acetone
dried (1)
0.7
6 118.0
0.68
100 mL Coulomat AK Input: syringe with needle
5 mL Coulomat CK
Stir/Titration time: 0/100 s
Isobutylmethylketone
dried (1)
0.4
6 717.0
0.18
100 mL Coulomat AK Input: syringe with needle
5 mL Coulomat CK
Stir/Titration time: 0/100 s
Ethyl acetate
dried (1)
0.5
6 34.9
1.2
100 mL Coulomat A
5 mL Coulomat C
Input: syringe with needle
Stir/Titration time: 0/48 s
Dimethylformamide
dried (1)
0.4
6 347.3
1.0
100 mL Coulomat A
5 mL Coulomat C
Input: syringe with needle
Stir/Titration time: 0/60 s
Sample 1 dried (1)
n-Hexane
Sample 2 dried (1)
100 mL Coulomat AK Cool sample to 0 °C
5 mL Coulomat CK
Input: syringe with needle
Standard titration parameters for all titrations:
Adjustment: control gain: 5; switch-off criterium: End level 0.1: µg/s (0.1 µg H2O/s above drift value)
automatic drift determination, automatic titration start
For toluene and n-hexane sample II:
control gain: 3; switch-off criterium: End level 0.05: µg/s (0.05 µg H2O/s above drift value)
(1) Dried over molecular sieve 3 Å
Reagents:
Coulomat A:
Coulomat C:
Coulomat AK:
Coulomat CK:
anode reagent HYDRANAL® Coulomat A, Riedel No. 34807
cathode reagent HYDRANAL® Coulomat C, Riedel No. 34808
anode reagent HYDRANAL® Coulomat AK, Riedel No. 34820
cathode reagent HYDRANAL® Coulomat CK, Riedel No. 34821
Anolyte:
Catholyte:
anode reagent KF reagent for coulometric water content determination, MERCK No. 9255
cathode reagent KF reagent for coulometric water content determination, MERCK No. 9255
18
METTLER, Karl Fischer Applications
Comments concerning applications using DL37
Dryed solvents contain little water, sometimes only traces, thus KF coulometry is particularly recommended.
Toluene and n-hexane Toluene and n-hexane sample II were dried for 24 hours over 3 Å molecular sieve.
n-Hexane sample I was dried for 1 hour over 3 Å molecular sieve.
These examples show that the METTLER DL37 KF coulometer allows reproducible results to be obtained even for trace amounts of water
(i.e., 4.6 ppm ± 0.4 ppm).
Cyclohexene, isopropa- The coulometric titration of these samples is straightforward.
nol, ethylene glycol,
ethylene chloride,
diethylether,
ethyl acetate
Acetone, Ketones react with methanol, generating ketals and water. To prevent this,
isobutylmethylketone a methanol-free anolyte and catholyte are used.
Acetaldehyde The boiling point of acetaldehyde is 15 °C. To simplify sample input with a
syringe, the sample should be cooled to approximately 0 °C.
In spite of the use of methanol-free reagents, acetal formation proceeds at a
rate that makes the coulometric water content determination impossible.
Dimethylformamide This compound is easily analyzed by KF coulometry. This is to be expected
for other acid amides as well.
These examples show that the METTLER DL37 KF Coulometer provides
reliable and exact values even in the trace water range, such as
4.6 ppm ± 0.4 ppm.
METTLER, Karl Fischer Applications
19
Karl Fischer Titration
Water Content Determination of Solvents
Sample: 2 g n-hexane dried over molecular sieve 3Å
Preparation:
Keep sample in a septum flask.
Method:
Sample Input:
Syringe with needle (i.e., ME-71482)
Catholyte:
5 mL Catholyte
(KF reagent for coulometric water
determination, MERCK No. 9255)
Anolyte:
100 mL Anolyte
(KF reagent for coulometric water
determination, MERCK No. 9255)
Comments:
Titration time: 50 seconds
Samples with low moisture contents in
the ppm range should be stored in
septum flasks. These samples are generally hygroscopic, thus the original
water content is considerably altered
and falsified by any contact with the
ambient (open flask, sample transfer,
etc.).
When removing the sample, the pressure loss should be compensated with
dried air only.
Results und Statistics:
Application:
Chemistry, petroleum products,
polymers, pharmaceuticals
Instruments:
METTLER DL37 KF Coulometer
A. Aichert, Application Laboratory, Nov. 1990
20
METTLER, Karl Fischer Applications
5. Petroleum Products
OIL
General Comments Mineral oils
Mineral oils can be completely dissolved only in the presence of chloroform. The chloroform may be replaced by 1-decanol or the special solvent
for oils and fats when analyzing light mineral oil products (i.e, benzene,
kerosine, diesel oil or heating oil). Crude oils, some of which contain tarry
components, are best dissolved in a methanol/chloroform/toluene mixture.
Motor oils contain additives that may interfere with the KF titration (such as
ketones, keto acids, zinc-dialkyl-dithiophosphates, calcium or magnesium
sulfonates). In this case the drying oven can be used. The temperature
should be adjusted to 120–140 °C, as the additives may decompose.
Mineral oils have low moisture contents (frequently less than 100 ppm).
For these samples, KF coulometry is particularly suitable. Crude oils contain insoluble impurities that may clog the diaphragm. The drying oven is
best used for these samples.
Silicon oils
The solubility of silicon oils must be improved by the addition of chloroform
or 1-decanol.
Fats
Some fats are not rendered soluble even after adding chloroform. In these
cases, external extraction in pure chloroform or use of the drying oven
(temperature 120–140 °C) have proven useful.
Parafins and waxes
Waxes and parafins may be titrated directly at 50 °C in a mixture of
methanol/chloroform. The determination using the drying oven is a further
possibility.
Tar and coal
Tarry products can be dissolved by adding toluene or xylene. The drying
oven can also be used for tar and coal.
References ISO/DIS 5381, Flüssige Petroleum Produkte – Wasserbestimmung nach
Karl Fischer
DIN 51777 Teil I, Test von Mineralöl, Kohlenwasserstoffen und Lösungsmittlen, Wasserbestimmung nach Karl Fischer. Direkte Methode.
ASTM-Standard, D-4377-88, 1988
Test method for water in crude oils (Karl Fischer Titration)
METTLER, Karl Fischer Applications
21
Applications: Petroleum products
A) Volumetric determination using DL35
Sample
Weight
Result
g
n %
RSD
%
Titrant
Solvent
Method
Gasoline
unleaded
2.5
6 0.0710
0.26
Titrant U 9233
50 mL LM F 9230
Input: syringe with needle
Stir time: 30 s
Diesel oil
5.0
6 0.0069
2.1
Titrant 2NH
20 mL solvent
20 mL 1-decanol
Input: syringe with needle
Stir time: 30 s
Petroleum
4.5
6 0.0077
0.72
Titrant 2NH
20 mL solvent
20 mL 1-decanol
Input: syringe with needle
Stir time: 30 s
Motor oil
2.5
6 0.0721
13.4
Composite 2
40 mL methanol
Evaporate moisture with drying oven
DO302: 140 °C, 200 mL N2/min
Stir time: 600 s
Motor oil
0.3
6 0.2261
0.94
Titrant 2NH
20 mL solvent
30 mL chloroform
Input: syringe with needle
Stir time: 60 s
Motor oil
used
2.5
6 0.0842
9.9
Composite 2
40 mL methanol
Evaporate moisture with drying oven
DO302: 140 °C, 200 mL N2/min
Stir time: 600 s
Silicon oil
4.0
9 0.0097
0.56
Titrant 2NH
20 mL solvent
20 mL 1-decanol
Input: syringe with needle
Stir time: 60 s
Crude oil
2.0
5 0.0206
2.9
Titrant 2NH
20 mL solvent
30 mL chloroform
Input: syringe with needle
Stir time: 60 s
multipurpose
grease
0.2
5 0.338
0.88
Titrant 2NH
40 mL solvent
External solution:
3 g in 80 g chloroform,
20 min at RT
Input: 5 mL aliquot with syringe
Ski wax
1.5
7 0.0417
1.3
Composite 2
25 mL methanol
25 mL toluene
Melt sample at 50 °C
Input: syringe with needle (warm)
Stir time: none
Shoe polish
2.0
5 0.0219
4.9
Composite 2
25 mL methanol
25 mL toluene
Melt sample at 50 °C
Input: syringe with needle (warm)
Stir time: none
Reagents:
Titrant 2NH:
Solvent:
Composite 2:
two component reagent HYDRANAL® Titrant 2NH, Riedel No. 34811 (titrant)
two component reagent HYDRANAL® Solvent, Riedel No. 34800 (solvent)
one component reagent HYDRANAL® Composite 2, Riedel No. 34806 (titrant)
Titrant U 9233:
LM F 9230:
two component reagent Titrant U 5 mg H2O/mL, MERCK No. 9233
two component reagent Solvent F (fats and oils), MERCK No. 9230
22
METTLER, Karl Fischer Applications
Comments concerning the applications using DL35
Gasoline, diesel oil, The solubility was improved by using 1-decanol or the special solvent for
petroleum oils and fats instead of chloroform.
Motor oil Motor oil contains additives to improve its usability. These are zinc-dialkyldithiophosphate, calcium sulfonate and magnesium sulfonate. New motor
oils contain 5–7% of these additives.
Motor oil may be titrated by adding chloroform; however, the resultant
values are too high due to side reactions with the additives.
Reliable values can be obtained by evaporating the moisture in a drying
oven at 140 °C and transferring the vapor into the titration cell with a dry
purge gas. At higher temperatures the additives will decompose, which will
also cause errors. The sample is injected through a septum directly into the
crucible using a syringe. The weight is determined by back-weighing.
Silicon oil 1-Decanol must be added to the solvent to completely dissolve the sample.
After 3 samples the solvent should be replaced, as its dissolving capacity
will be exhausted.
Crude oil The sample can be dissolved completely only by adding chloroform to the
solvent. 1-Decanol no longer suffices. Replace solvent after each sample,
as its dissolving capacity is quickly exhausted.
Multi-purpose grease This fat is incompletely soluble even after adding chloroform. For this reason an external extraction with chloroform was used.
A determination using the drying oven at 180 °C is a further possibility.
At higher temperatures, however, the sample will polymerize.
Ski wax, shoe polish The sample is melted in a sealed flask at approximately 50 °C. A prewarmed syringe is used for sample input. The syringe may be warmed
using a hair dryer for instance. This procedure is necessary as the sample
will solidify immediately in a cold syringe.
The addition of toluene and heating the titration solution to approx. 30 °C
results in a suspension which can easily be titrated. The solvent must be
replaced after 3 samples, otherwise the sample will begin to precipitate.
This will cover the electrode.
The titration solution was kept at 30–35 °C using a thermostatable titration
beaker (ME-23976) with a circulating water bath.
METTLER, Karl Fischer Applications
23
Applications: Petroleum products
B) Coulometric determination using DL37
Sample
Weight
g
n
Result
ppm
RSD
%
Reagents
Gasoline
super
0.6
13 769.3
0.5
100 mL Coulomat A Input: syringe with needle
5 mL Coulomat C
Stir/Titration time: 0/50 s
Kerosene
2.5
(flight benzene)
7
36.1
1.4
100 mL Coulomat A Input: syringe with needle
5 mL Coulomat C
Stir/Titration time: 0/75 s
Petroleum dried
0.5
6
43.4
2.5
100 mL Coulomat A Input: syringe with needle
5 mL Coulomat C
Stir/Titration time: 0/30 s
Hydraulic oil
0.5
6
579.8
2.0
70 mL Coulomat A
30 mL chloroform
5 mL Coulomat C
Input: syringe with needle
Stir/Titration time: 0/180 s
Turbine oil
3.0
3
33.5
1.0
70 mL Coulomat A
30 mL chloroform
5 mL Coulomat C
Input: syringe with needle
Stir/Titration time: 0/180 s
Transformer
oil
10.0
5
30.4
1.9
100 mL Coulomat A Input: syringe with needle
5 mL Coulomat C
Stir/Titration time: 0 / 180 s
Brake fluid
0.3
7
1081.2 0.38
100 mL Anolyte
5 mL Catholyte
Silicon oil
0.5
6
103.5
1.7
100 mL Coulomat A Input: syringe with needle
5 mL Coulomat C
Stir/Titration time: 0/50 s
Paraffin
granulate
3.0
6
31.0
15.9
100 mL Coulomat A Evaporate moisture with drying oven
5 mL Coulomat C
DO337: 150 °C, 200 mL air/min
Stir/Titration time: 0/900 s
Crude oil
3.0
5
202.0
6.6
100 mL Coulomat A Evaporate moisture with drying oven
5 mL Coulomat C
DO337: 130 °C, 200 mL air/min
Stir/Titration time: 0/1200 s
Soot
0.8
5
3582.7 1.5
with molecular sieve
100 mL Anolyte
5 mL Catholyte
Method
Input: syringe with needle
Stir/Titration time: 0/210 s
Evaporate moisture with drying oven
DO337: 200 °C, 200 mL N2/min
Stir/Titration time: 0/900 s
Standard titration parameters for all titrations:
Adjustment: control gain: 5; switch-off criterium: End level 0.1µg/s (0.1 µg H2O/s above drift value)
automatic drift determination, automatic titration start
Titration parameters for titrations using DO337 drying oven:
Adjustment: control gain: 5; switch-off criterium: fixed titration time and End level 0.05 µg/s
automatic drift determination, manual titration start
Reagents:
Coulomat A:
Coulomat C:
anode reagent HYDRANAL© Coulomat A, Riedel No. 34807
cathode reagent HYDRANAL© Coulomat C Riedel No. 34808
Anolyte:
Catholyte:
anode reagent KF reagent for coulometric water content determination, MERCK No. 9255
cathode reagent KF reagent for coulometric water content determination, MERCK No. 9255
24
METTLER, Karl Fischer Applications
Comments concerning the applications using DL37
Mineral oil products have low moisture contents, sometimes only traces,
thus KF coulometry can be particularly recommended.
Gasoline, kerosine, Coulomat A contains chloroform, thus these samples can be titrated without
petroleum adding chloroform. After 2–3 samples the dissolving capacity of the solvent
is exhausted and an emulsion results. Even in this condition, correct and
reproducible results can be obtained by coulometric titration.
Turbine and Adding chloroform to these oils gives an emulsion which can be titrated
hydraulic oil directly. The emulsive quality of these heavy oils is not as good as that of
gasoline or petroleum. The titration time is longer and the reproducibility
poorer.
These oils can also be titrated using the drying oven: the moisture is evaporated at 130 °C and the vapor transferred into the titration cell using a dry
purge gas.
Transformer oil This oil can be titrated directly as an emulsion. The rather low moisture
content requires a higher sample weight.
Silicon oil Silicon oil can be titrated directly as an emulsion without adding chloroform. The emulsive quality is very good. The titration time is short, the
reproducibility high.
Paraffin This can be dissolved only in a chloroform/methanol mixture at approx.
50 °C. Coulometric determinations at elevated temperatures, however, are
not possible due to limits imposed by the DL37. For this reason the drying
oven is used.
When air is used as the purge gas, the drying temperature may not exceed
180 °C. At 200 °C the product begins to oxidize after only 10 minutes.
The oxidation process releases water. The poor reproducibility is primarily
caused by the inhomogeneity of the sample granules.
Crude oil Crude oil contains insoluble contaminants that can clog the diaphragm.
Thus the drying oven is the method of choice. The sample input of the
crude oil is best achieved by injecting the oil through a septum directly into
the crucible. Weight determination by back-weighing.
A direct titration with chloroform addition gives erroneous results:
– the sample is merely emulsified and the water released only partially
– moisture content too low
(mean from 6 samples = 128.9 ppm, RSD = 0.7%)
– black deposit in the titration cell, cell must be cleaned
Soot The coulometric determination using the drying oven is straightforward.
A direct determination using volumetric KF titration (DL35) by adding formamide or chloroform gives results that are too low, as the soot dissolves
incompletely and the water is only partially released.
METTLER, Karl Fischer Applications
25
Karl Fischer Titration
Water Content Determination of Mineral Oil
Sample: 2 g Crude oil
Preparation:
Keep sample in a septum flask
Sample Input:
Syringe with needle (e.g., ME-71482)
Titrant:
KF titrant, 2 mg H2O/mL
(HYDRANAL® Titrant 2NH No. 34811)
Solvent:
20 mL KF solvent
(HYDRANAL® Solvent, No. 34800)
30 mL chloroform
Comments:
Stir time: 60 seconds
Samples with moisture contents in the
ppm range should be stored in septum
flasks. The samples are generally hygroscopic. The original moisture content is rapidly and significantly altered
by any contact with the ambient (opening the flask, transferring the sample,
etc.).
After removing the sample from the
flask, the pressure difference should be
compensated with dry air only.
A three-hole adaptor (ME-23982) is
recommended for the sample input
using a syringe.
Replace the solvent after 2 samples, as
the dissolving capacity is exhausted.
Titrations of incompletely dissolved
samples (such as emulsions) give lower results.
Results und Statistics:
Application:
Petrochemical industry
Instruments:
METTLER DL35 Karl Fischer Titrator
Electrode DM 142
Matrix printer Epson LX-800
A. Aichert, Application Laboratory, Dez. 1990
26
METTLER, Karl Fischer Applications
6. Plastics and Adhesives
Glue
General comments Plastics
Water is usually occluded in plastics. It is released very slowly and incompletely by diffusion. Most plastics are not soluble in a KF solvent or solvent
mixture. Therefore the moisture is usually evaporated in a drying oven,
then the vapor is driven into the titration cell using a dry purge gas. External
extraction in methanol, if necessary at 50°C, is also possible.
Plastics have low moisture contents (often less than 100 ppm), so that KF
coulometry is especially recommendable.
Ion exchanger
Ion exchange resins are insoluble in organic solvents. For this reason, the
drying oven is used to evaporate the moisture. The vapor is driven into the
KF cell using a dry purge gas.
Adhesives
The water content of adhesives can be determined directly. In some cases
chloroform may be necessary to completely dissolve the sample.
References Muroi, K., Determination of Water in Plastic Materials by Karl Fischer
Method, Bunseki Kagaku 11, 351 (1962)
Praeger, K. and Dinse, H.D., Experiences in the Determination of Small
Amounts of Water in Polyethylene and Polyamide
Faserforsch. Textiltechn. 21, 37-38 (1970)
DIN 53715 Wasserbestimmung von pulverförmigen Kunststoffen nach Karl
Fischer
ASTM Designation: D 789-81 Standard Specification for Nylon Injection
Molding and Extrusion Materials
Sharma, H.D. and Subrramanian, N., Determination of Water in IonExchange Resins by Karl Fischer
Anal. Chem. 41, 2063-2064 (1969)
Anal. Chem. 42, 1278-1290 (1970)
van Acker, P., de Cote, F. and Hoste, J., Determination of Water in Strong
Base Anion-Exchange Resins by the Karl Fischer Titration
Anal. Chim. Acta. 73, 198-203 (1974)
METTLER, Karl Fischer Applications
27
Applications: Plastics and Adhesives
A) Volumetric determination using DL35
Sample
Weight
g
n
Polyethylene
granules
3.0
Polyamide
granules
RSD
%
Titrant
Solvent
6 0.0068
6.9
ReAquant 3.5
Evaporate moisture with drying oven
40 mL solvent Sprint DO337: 280 °C, 200 mL N2/min
Stir time: 600 s
2.0
6 0.5547
0.67
Composite 5
40 mL methanol
Evaporate moisture with drying oven
DO302: 190 °C, 200 mL N2/min
Stir time: 900 s
Epoxy resin
fluid
0.05
5 0.258
2.6
Titrant 2NH
20 mL solvent
20 mL chloroform
Input: syringe with needle
Stir time: 60 s
Glue stick
0.05
6 46.3
0.94
Composite 5
20 mL methanol
20 mL chloroform
Input: spatula
Stir time: 100 s
All-purpose glue 0.2
Cyanoacryl glue
7 1.28
2.2
Titrant 2NH
30 mL solvent
Input: tube with needle
Stir time: 60 s
Rubber
cement
6 0.287
5.3
Titrant 2NH
10 mL solvent
30 mL chloroform
External dissolution:
4 g in 85 g chloroform; 10 min. RT
Input: 1 mL aliquot with syringe
0.1
Result
%
Method
Reagents:
Titrant 2NH:
Solvent:
Composite 5:
two component reagent HYDRANAL® Titrant 2NH, Riedel No. 34811 (titrant)
two component reagent HYDRANAL® Solvent, Riedel No. 34800 (solvent)
one component reagent HYDRANAL® Composite 5, Riedel No. 34805 (titrant)
ReAquant 3.5:
Solvent Sprint:
two component reagent ReAquant ® 3.5 mg H2O/mL, J.T.Baker No. 8842 (titrant)
two component reagent ReAquant ® Solvent Sprint, J.T.Baker No. 8855 (solvent)
B) Coulometric determination using DL37
Sample
Weight
Result
g
n ppm
RSD
%
Reagents
Method
Polyethylene
granules
2.0
6 68.7
8.2
100 mL Coulomat A
5 mL Coulomat C
Evaporate moisture with drying oven
DO337: 180 °C 200 mL air/min
Stir/Titration time: 0/600 s
Polypropylene
granules
2.0
6 148.3
5.4
100 mL Coulomat A
5 mL Coulomat C
Evaporate moisture with drying oven
DO337: 180 °C 200 mL air/min
Stir/Titration time: 0/600 s
Polystyrene
granules
2.0
6 322.2
2.4
100 mL Coulomat A
5 mL Coulomat C
Evaporate moisture with drying oven
DO337: 160 °C 200 mL air/min
Stir/Titration time: 0/900 s
PVC foil
0.1
6 638.1
2.2
100 mL Coulomat A
5 mL Coulomat C
Evaporate moisture with drying oven
DO337: 150 °C 200 mL air/min
Stir/Titration time: 0/240 s
Standard titration parameters for titrations with drying oven DO337:
Adjustment: control gain: 5; (for PVC foil: control gain: 3)
switch-off criterium: fixed titration time and End level 0.05 µg/s
automatic drift determination, manual titration start
Reagents:
Coulomat A:
Coulomat C:
28
anode reagent HYDRANAL® Coulomat A, Riedel No. 34807
cathode reagent HYDRANAL® Coulomat C, Riedel No. 34808
METTLER, Karl Fischer Applications
Comments concerning applications using DL35
Polyethylene
The sample melts and, once cooled, sticks to the weighing boat. Line the
weighing boat with aluminum foil to facilitate sample removal.
Due to the low moisture content, the drift must be determined prior to each
sample to ensure a good reproducibility.
Polyamide
The use of too high temperatures for polyamides may result in a continual
condensation reaction which frees water and artificially elevates the water
content. For this reason, the sample was first tested at 120°C for 2 hours;
result: 0.5445%. The temperature was then elevated to 190°C and the
time drastically reduced; result: 0.5547%.
Epoxy resin (fluid)
Glue stick
All-purpose glue
(cyanoacryl glue)
Rubber cement
Chloroform was added to the solvent to competely dissolve the sample.
After 4 samples the solvent should be replaced, as its dissolving capacity
will be exhausted.
Chloroform must be added to the solvent to ensure that the sample dissolves completely. All 6 samples can be titrated in the same solvent.
The end of the tube was fitted with an injection needle with a large inner
diameter (1.2 mm) for the sample input.
As the sample is poorly soluble in the solvent/chloroform mixture, it was
externally dissolved in chloroform.
A solvent/chloroform mixture must be used for titration of the solution. The
rubber precipitates in pure solvent and will cover the electrode.
The solvent must be replaced and the electrode cleaned (deposit on the
electrode) after each titration.
Comments concerning applications using DL37
Polyethylene,
polypropylene,
polystyrene
When air is used as the carrier gas, the oven temperature may not exceed
180 °C. At 220 °C the polyethylene and polypropylene will oxidize in a
process that generates water.
The cooled sample will stick to the weighing boat. Line boat with aluminum foil to facilitate sample removal.
PVC foil
The foil is cut into approximately 3 cm2 pieces. These will fit easily into the
drying oven crucible. The sample should not touch the inner wall of the
drying oven, as the PVC will stick to it.
METTLER, Karl Fischer Applications
29
Karl Fischer Titration
Water Content Determination of Plastics
Sample: 3 g Polyethylene granulate
Preparation:
Place sample in drying oven. Evaporate moisture and transfer the vapor
into the titration cell with a dry purge
gas.
Oven temperature: 280 °C
Purge gas stream: 200 mL N2/min
Sample input:
Weighing boat
Titrant:
KF titrant 3.5 mg H2O/mL
(ReAquant® Titrant, J.T. Baker
No. 8842)
Solvent:
40 mL KF solvent
(ReAquant® Solvent, J.T. Baker
No. 8855)
Results und Statistics:
Comments:
Stir time: 600 s
METTLER method No. 50
The sample melts and, once cooled,
will stick to the weighing boat. Line
weighing boat with aluminum foil to
facilitate sample removal.
Application:
Polymer industry
Instruments:
METTLER DL35 Karl Fischer Titrator
Electrode DM142
Drying oven METTLER DO302
Matrix printer Epson LX-800
A. Aichert, Application Laboratory, Dez. 1990
30
METTLER, Karl Fischer Applications
7. Medicines (Pharmaceuticals)
General comments In the pharmaceutical industry, moisture contents of active substances, the
raw materials required to synthesize these, and the final products themselves are determined.
Raw materials
The raw materials used by the pharmaceutical industry are organic and
inorganic raw materials as well as solvents. The moisture content determinations of these products are described in Chapters 2–4.
Active substances
The pharmaceutically active substances are generally organic or inorganic
compounds which are soluble in methanol. These can usually be titrated
unproblematically. Aldehydes, ketones and some amides require the use of
methanol-free reagents, as their esterification reactions lead to incorrectly
high water contents.
Lyophilized substrates
Injectable substances are sometimes delivered as dried substrates, to prolong the usability of active substances. Here the residual water content is a
crucial factor. This water content will be around 100 µg H2O per ampule.
Tablets
Tablets may contain substances that will react with KF reagents in side
reactions. This is the case for magnesium and aluminum hydroxides, for
example. Both compounds are used as antacids.
Ointments, oils, suppositories
The solubility of oils and ointments may be improved by adding chloroform
or 1-decanol. The USP XXI recommends a mixture of carbon tetrachloride :
chloroform : methanol 2:2:1 for ointments. Suppositories can be dissolved
by adding chloroform and elevating the temperature.
References Cachet, T. and Hoogmartens, J., Determination of water in erythromycin by
Karl Fischer titration, J. Pharm. Biomed. Anal. ISSN 0731-7085; 6,5,461472 (1988)
Müller, M., Determination of water in erythromycin by Karl Fischer titration,
Dtsch. Apoth. Ztg. ISSN 0011-9857; 127, 41, 2034-2036 (1987)
Use of a simple Karl Fischer apparatus for water determination in lyophilized radiopharmaceutical kits, Appl. Radiot. Isot. ISSN 0883-2889; 38,
11, 992-993 (1987)
Lindquist, J., Determination of water in penicillins using Karl Fischer
reagents, J. Pharm. Biomed. Anal. ISSN 0731-7085; 2,1,37-44, 1984
METTLER, Karl Fischer Applications
31
Applications: Medicines
A) Volumetric determination using DL35
Sample
Weight
Result
g
n %
RSD
%
Titrant
Solvent
Method
Aspirin
0.2
6 1.53
1.9
Titrant U 9233
30 mL LM 9241
Crush sample
Input: weighing boat
Stir time: 600 s
Antibiotics
dry
0.2
6 4.56
1.0
Titrant U 9233
Input: weighing boat
30 mL LM K 9221 Stir time: 300 s
2 drops Triton X100 Stir rapidly
Antibiotics
suspension
0.03
6 95.8
0.24
Titrant U 9233
30 mL LM 9241
Input: syringe with needle
Stir time: none
Disinfectant
powder
1.0
6 0.0620
1.5
Titrant 2NH
30 mL solvent
Input: weighing boat
Stir time: 120 s
Cough drops
0.1
6 6.25
0.13
Titrant U 9233
30 mL LM 9241
Input: syringe with needle
Stir time: none
Valerian
essence
0.1
6 29.3
0.14
Titrant 9258
30 mL methanol
Input: syringe with needle
Stir time: none
Chamomile
extract
0.03
6 43.2
0.12
Titrant 9258
30 mL methanol
Input: syringe with needle
Stir time: none
Tonic
0.05
6 57.0
0.26
Titrant U 9233
25 mL LM 9241
15 mL formamide
Input: syringe with needle
Stir time: none
Gel for
sprains and
infections
0.7
6 42.3
0.51
Titrant U 9233
30 mL LM 9241
Input: syringe with needle
Stir time: 30 s
Ointment
base
0.03
5 71.2
0.74
Titrant U 9233
40 mL LM F 9230
Input: syringe with needle
Stir time: 30 s
Ointment
for burns
0.03
5 54.7
0.40
Titrant U 9233
40 mL LM F 9230
Input: syringe with needle
Stir time: 60 s
Suppository
1.0
6 0.0023
13.3
Titrant 2NH
30 mL solvent
15 mL toluene
Input: with tweezers
Stir time: 60 s
Titrate at 50 °C
Reagents:
Titrant 2NH:
Solvent:
Titrant 9243:
Titrant U 9233:
LM 9241:
LM K 9221:
LM F 9230:
Titrant 9258
32
two component reagent HYDRANAL® Titrant 2NH, Riedel No. 34811 (titrant)
two component reagent HYDRANAL® Solvent, Riedel No. 34800 (solvent)
two component reagent Titrant 5 mg H2O/mL, MERCK No. 9243
two copmponent reagent Titrant U 5 mg H2O/mL, MERCK No. 9233
two component reagent Solvent, MERCK No. 9241
two component reagent Solvent K (for ketones and aldehydes), MERCK No. 9221
two component reagent Solvent F (for fats and oils), MERCK No. 9230
one component reagent Titrant 5 mg H2O/mL, MERCK No. 9258
METTLER, Karl Fischer Applications
Comments concerning the applications using DL35
Aspirin The finely crushed sample does not dissolve completely. To ensure the
complete release of all water, stir for 10 minutes.
Antibiotics (dry) This sample is not dense and is poorly wettable with the solvent. Lumps
form which contain undissolved substances. Lump formation can be
avoided by adding a detergent (Triton X100) and by stirring vigorously.
The sample will then dissolve completely.
An elevated post-consumption can be observed when using regular solvents. This effect can be eliminated by using a methanol-free solvent.
Antibiotics (suspension) The direct titration is straightforward.
Disinfectant powder This powder is insoluble in the KF solvent. A direct titration as a suspension
is possible. Even with a stir time of only 2 minutes, no post-consumption
takes place, thus the water has been completely released.
Chamomile extract, Titrate directly.
couph drops and
valerian extract
Tonic When using the normal solvent of the two component reagent as well as
methanol, a gel drop forms which immediately deposits itself on the
platinum point of the electrode. This results in an over-titration. By adding
formamide this effect can be avoided.
Gels, ointments These samples are filled into the back end of a syringe for the sample input.
No needle is used due to the sample consistency.
The gel dissolves in the solvent of the two component reagent.
The complete dissolution of fat-based ointments requires the addition of
chloroform, 1-decanol or the special solvent for fats and oils.
Suppositories One complete suppository is used for each titration. (The weight is constant:
1.0 g). In the solvent/toluene mixture the suppositories dissolve (melt)
completely at 50 °C. The solvent must be replaced after 2–3 samples, as
the samples no longer dissolve completely. This leads to a decrease in the
reproducibility.
METTLER, Karl Fischer Applications
33
Applications: Medicines
B) Coulometric determination using DL37
Sample
Weight
Result
g
n ppm
RSD
%
Reagents
Method
Massage oil
0.3
6 1059
0.21
100 mL Coulomat A
5 mL Coulomat C
Input: syringe with needle
Stir/Titration time: 0/60 s
Eucalyptus
oil
0.1
6 1267
0.39
100 mL Coulomat A
5 mL Coulomat C
Input: syringe with needle
Stir/Titration time: 0/100 s
Titration parameters:
Adjustment: control gain: 5; switch-off criterium: End level 0.1 µg/s (0.1 µg H2O/s above drift value)
automatic drift determination, automatic titration start
Sample
Lot No.
Flask
Result
Reagents
µg H2O
Method
Lyophilized
Plasma
2BOA
1
2
3
4
771.3
699.3
759.2
665.7
Dissolve in septum flask with
5 mL titrated Coulomat A
Input: syringe with needle
Stir/Titration time: 0/150 s
RRO5
1
2
3
4
720.7
648.7
729.3
619.1
100 mL Coulomat A
5 mL Coulomat C
Titration parameters:
Adjustment: control gain: 2; switch-off criterium: End level 0.1 µg/s (0.1 µg H2O/s above drift value)
automatic drift determination, manual titration start
Reagents:
Coulomat A:
Coulomat C:
anode reagent HYDRANAL® Coulomat A, Riedel No. 34807
cathode reagent HYDRANAL® Coulomat C, Riedel No. 34808
Comments concerning the applications using DL37
34
Eucalyptus and
massage oils
The direct titration is unproblematic. The addition of chloroform is unnecessary.
Lyophilized plasma
An external dissolution of the lyophilisate is not recommendable due to the
low moisture content. The correction factor for the solvent blank is too high
compared to the water content of the sample. Therefore, the following
procedure is used: approximately 5 mL anolyte are removed from the anolyte space of the titration cell with a plastic syringe. This is filled back into
the titration cell. The syringe is rinsed in this manner until it is dry. Then
5 mL anolyte are taken up in the syringe and injected through a septum
into the sample flask. The lyophilisate is suspended by shaking the flask
(5 minutes in the sonicator). The entire suspension is then pulled back into
the syringe, injected into the titration cell, and the water content is determined.
The pressure compensation for sample removal must be achieved using
dry air.
METTLER, Karl Fischer Applications
8. Dyes and Agrochemicals
General Comments Dyes
A large number of dyes are soluble in methanol; these can be titrated easily.
Insoluble dyes, such as pigments, can be titrated directly as a suspension.
Using this procedure, only the adherent moisture will be determined.
A direct titration of water-based dispersion paints and lacquers can also be
undertaken. When titrating lacquers, care must be taken in the choice of a
solvent. Ketones or reactive amines require the use of a methanol-free solvent to prevent interferences caused by side reactions with the KF reagents.
Agrochemicals
Agrochemicals are supplied in solution (with organic solvents), waterbased suspensions or as powders.
Unpolar solvents are generally used for the solution; thus, the samples can
be completely dissolved only by adding chloroform or 1-decanol. The
moisture content of these is low so that the coulometric method is feasible.
The water-based suspensions are best titrated using a direct volumetric
titration.
Powders rarely dissolve in most KF solvents. Suspensions of these powders
allow the determination of the adherent moisture only.
References ASTM D 4017-81 Standard Test Method for Water in Paints and Paint
Materials by Karl Fischer Method
METTLER, Karl Fischer Applications
35
Applications: Dyes and agrochemicals
A) Volumetric determination using DL35
Sample
Weight
g
n
Optical
brightener
0.3
Wool dye
Orange R
Reactive dye
scarlett F-3G
RSD
%
Titrant
Solvent
Method
6 3.87
0.76
Titrant 9258
30 mL methanol
Input: weighing boat
Stir time: 300 s
0.25
6 10.99
0.14
Titrant 9258
40 mL methanol
Input: weighing boat
Stir time: 30 s
0.3
6 5.24
0.42
Titrant 9258
40 mL methanol
Input: weighing boat
Stir time: 60 s
Indicator dye
0.6
methanile yellow
6 0.928
1.0
Titrant 9258
40 mL methanol
Input: weighing boat
Stir time: 120 s
Dispersion
dye olive
0.3
6 6.91
0.22
ReAquant 5
Input: weighing boat
30 mL solvent Sprint Stir time: 300 s
25 mL formamide
Acrylic paint
water based
0.05
6 54.3
0.47
Titrant U 9233
25 mL LM 9241
15 mL formamide
External solution:
3.6 g in 20 mL formamide
Input: 1 mL aliquot with syringe
Synthetic
enamel
1.5
6 0.0906
3.4
Titrant U 9233
20 mL LM 9241
20 mL toluene
Input: syringe with needle
Stir time: none
Insecticide
biological
2.0
6 0.0977
0.56
Titrant 60626
30 mL LM 60625
20 mL 1-decanol
Input: syringe with needle
Stir time: none
Insecticide
Diazinon
2.0
6 0.1461
0.21
Titrant 60626
30 mL LM 60625
10 mL 1-decanol
Input: syringe with needle
Stir time: none
Rose fungicide 0.03
watery emulsion
6 58.3
0.25
Titrant 60626
30 mL LM 60625
Input: syringe with needle
Stir time: none
Herbicide
powder
1.0
6 1.20
0.49
Titrant U 9233
30 mL LM 9241
Input: weighing boat
Stir time: 180 s
Insecticide
ant killer
1.0
6 0.273
2.6
Titrant 60626
30 mL LM 60625
Input: weighing boat
Stir time: 180 s
Reagents:
Titrant U 9233:
LM 9241:
Titrant 9258:
Titrant 60625:
LM 60625:
ReAquant 5:
Solvent Sprint:
36
Result
%
two component reagent Titrant U 5 mg H2O/mL, MERCK No. 9233
two component reagent Solvent, MERCK No. 9241
one component reagent Titrant 5 mg H2O/mL, MERCK No. 9258
two component reagent Titrant 5 mg H2O/mL, FLUKA No.60626
two component reagent Solvent, FLUKA No. 60625
two component reagent ReAquant® 5 mg H2O/mL, J.T. Baker No. 8844 (titrant)
two component reagent ReAquant® Solvent Sprint, J.T. Baker No. 8855 (solvent)
METTLER, Karl Fischer Applications
B) Coulometric determination using DL37
Sample
Weight
Result
g
n ppm
RSD
%
Reagents
Method
Rose fungicide
solution
0.5
0.36
100 mL Anolyte
5 mL Catholyte
Input: syringe with needle
Stir/Titration time: 0/90 s
6 828.6
Titration parameters for the titration:
Adjustment: control gain: 3; switch-off criterium: End level: 0.1 µg/s
automatic drift determination, automatic titration start
Reagents:
Anolyte:
Catholyte:
anode reagent KF reagent for coulometric water content determination, MERCK No. 9255
cathode reagent KF reagent for coulometric water content determination, MERCK No. 9255
Comments concerning the applications
Optical brightener This sample is not soluble in KF solvents; it can, however, be suspended.
A direct titration with a 5-minutes stir time in methanol is possible. After
2 samples, the solvent should be replaced and the electrode cleaned (forms
deposit).
Wool, reactive and These samples are easily dissolved in methanol. The dissolving capacity of
indicator dyes the solvent is limited; replace the solvent after 3–4 samples.
Dispersion dye This sample is insoluble in KF solvents. It can be titrated directly as a
suspension by adding formamide. In pure methanol the water is released
slowly and incompletely (result: 6.6% with 30 minutes titration time).
Acrylic paint A direct titration in a formamide/solvent mixture results in the sample sticking to titration cell and electrode, and is not a feasible alternative. The
sample is dissolved in pure formamide and this solution is added to the
formamide/solvent mixture. The resulting emulsion can be titrated straightforwardly (slightly increased post-consumption). Replace the solvent after
2 samples.
Synthetic enamel The sample is added to a prepared toluene/solvent mixture. The resulting
fine emulsion can be titrated unproblematically (slightly increased postconsumption). Replace solvent after 2 titrations.
Insecticide and rose These samples (active agent plus solvent) are soluble only in the presence
fungicide (solutions) of 1-decanol. If an emulsion is prepared, somewhat lower values will result.
Due to the low moisture content, a coulometric determination is a further
possibility.
Rose fungicide The direct tiration is unproblematic.
(water-based emulsion)
Insecticide and These samples are insoluble in KF solvents. A direct titration is possible with
herbicide a 3-minutes stir time. (No elevated post-consumption). After 3 samples
have been titrated, the water content values decrease (replace solvent).
METTLER, Karl Fischer Applications
37
9. Detergents and Surfactants
General comments For these products, which are solids, liquids or pastes, a direct KF titration
can easily be undertaken.
Detergents containing hydroxide or perborate result in elevated water
content values, as these compounds undergo a side reaction with the KF
reagent.
References ISO 4317-1977 Surface-Active Agents – Determination of Water – Karl
Fischer Method
Comments concerning the applications
Laundry detergent This detergent contains perborate, which reacts with the KF reagent in a
side reaction. For this reason the moisture is evaporated in the drying
oven at 150 °C and the vapor is transferred to the titration cell by a dry
purge gas.
Detergent for fine These detergents contain neither hydroxides nor perborates. They can be
washables titrated directly.
Cleaner, dish detergent, These samples dissolve in the solvent. The direct titration is straightforward.
soft soap Caution: beware of the water dissolving capacity of the KF solvent (replace
solvent after 3–4 samples).
Fabric softener, These emulsions can be titrated directly without encountering problems.
impregnation agent
Non-ionic-surfactant The direct titration is straightforward. The coulometric determination can
be used for samples with a low moisture content.
38
METTLER, Karl Fischer Applications
Applications Detergents and Surfactants
A) Volumetric determination using DL35
Sample
Weight
Result
g
n %
RSD
%
Titrant
Solvent
Method
Laundry
detergent
0.1
6 13.7
2.3
ReAquant 5
30 mL solvent
Evaporate moisture with drying oven
DO302: 150 °C, 200 mL N2/min
Stir time: 1200 s
Detergent for
fine washables
30–60 °C
0.2
6 6.13
1.2
ReAquant 5
30 mL solvent
Input:weighing boat
Stir time: 500 s
Liquid
detergent
0.03
6 81.7
0.60
ReAquant 5
30 mL solvent
Input: syringe with needle
Stir time: none
Cleaner
liquid
0.03
5 73.9
0.25
ReAquant 5
30 mL solvent
Input: syringe with needle
Stir time: none
Dish detergent
liquid
0.03
6 73.0
0.39
ReAquant 5
30 mL solvent
Input: syringe with needle
Stir time: none
Soft soap
0.03
6 76.4
1.3
ReAquant 5
30 mL solvent
Input: syringe with needle
Stir time: none
Fabric softener
cocentrate
0.03
6 84.3
0.37
ReAquant 5
30 mL solvent
Input: syringe with needle
Stir time: none
Impregnation
agent
0.03
6 61.4
0.32
ReAquant 5
30 mL solvent
Input: syringe with needle
Stir time: 120 s
6 0.160
0.84
ReAquant 3.5
30 mL solvent
Input: syringe with needle
Stir time: none
non-ionic
2.0
surfactant
alkylphenylpolyethyleneglycol
Reagents:
ReAquant 5:
ReAquant 3.5:
Solvent:
two component reagent ReAquant ® 5 mg H2O/mL, J.T. Baker No. 8844 (titrant)
two component reagent ReAquant ® 3.5 mg H2O/mL, J.T. Baker No. 8842 (titrant)
two component reagent ReAquant ® Solvent Sprint, J.T. Baker No. 8855 (solvent)
B) Coulometric determination using DL37
Sample
Weight
Result
g
n ppm
RSD
%
Reagents
Method
Non-ionic
surfactant
nonyl phenylethylene glycol
0.25
0.58
100 mL Anolyte
5 mL Catholyte
Input: syringe with needle
Stir/Titration time: 0/90 s
6 718.4
Titration parameters for all titrations:
Adjustment: control gain: 3; switch-off criterium: End level: 0.1 mg/s
automatic drift determination, automatic titration start
Reagents:
Anolyte:
Catholyte:
anode reagent KF reagent for coulometric water content determination, MERCK No. 9255
cathode reagent KF reagent for coulometric water content determination, MERCK No. 9255
METTLER, Karl Fischer Applications
39
10. Silk, Wool, Cellulose, Paper and Wood
General comments Wool and cellulose
Wool and cellulose release water easily. Since these products are insoluble in KF solvents, an external extraction must be performed. Methanol is
the usual solvent for the extraction. The drying oven can also be used.
Paper
A low moisture content is a criterium of the quality, especially for insulation paper. The KF determination is usually performed by external extraction in methanol or in a methanol/chloroform mixture. If the drying oven is
to be used, the temperature should be adjusted to 105–130 °C.
Wood
The KF moisture determination of wood can be achieved using either an
external extraction in methanol, or the drying oven in the 105–130 °C
temperature range.
References ASTM D 1348-61 Standard Test Method for Moisture in Cellulose
Fujino, H. and Muroi, K., Determination of Water Content in Electric Insulation Papers by Karl Fischer Method, Bunseki Kagaku 30, 624 (1981)
Comments concerning the applications with DL35
Wood Wood releases water slowly. A direct titration is not possible. Thus the
moisture is evaporated in the drying oven at 140 °C and the vapor is
transferred into the KF titration cell using dry nitrogen as the purge gas.
At higher temperatures the wood slowly darkens (decomposes slowly),
which leads to an increase in the water content.
Wool and silk An external extraction is the method of choice for samples of this nature.
Cellulose powder The finely crushed cellulose powder releases water reluctantly. A direct
titration can be performed with a 15-minutes stir time, with the sample
suspended in the KF solvent.
40
METTLER, Karl Fischer Applications
Applications: Silk, wool, cellulose, paper, wood
A) Volumetric determination using DL35
Sample
Weight
Result
g
n %
RSD
%
Titrant
Solvent
Method
Wood (pine)
0.5
6 8.28
0.70
Titrant 9258
40 mL methanol
Evaporate moisture in drying oven
DO302: 140 °C, 200 mL N2/min
Stir time: 900 s
Virgin wool
0.08
6 9.84
0.24
Titrant U 9233
30 mL LM 9241
External extraction.
2.1 g in 52 g methanol, 1 h at RT
Input: 3 mL aliquot with syringe
Silk
0.07
6 6.83
0.35
Titrant U 9233
30 mL LM 9241
External extraction:
1.1 g in 42 g methanol, 1 h at RT
Input: 3 mL aliquot with syringe
Cellulose
powder
0.2
6 4.23
0.66
Titrant U 9233
30 mL LM 9241
Input: weighing boat
Stir time: 15 minutes
Reagents:
Titrant U 9233:
LM 9241:
Titrant 9258:
two component reagent Titrant U 5 mg H2O/mL, MERCK No. 9233
two component reagent Solvent, MERCK No. 9241
one component reagent Titrant 5 mg H2O/mL, MERCK No. 9258
B) Coulometric determination using DL37
Sample
Weight
Result
g
n ppm
RSD
%
Reagents
Method
Copying paper
white
0.03
6 4.88
1.0
100 mL Coulomat A Evaporate moisture with drying oven
5 mL Coulomat C
DO337: 140 °C, 200 mL air/min
Stir/Titration time: 0/600 s
Copying paper
recycled
0.06
6 4.98
0.51
100 mL Coulomat A Evaporate moisture with drying oven
5 mL Coulomat C
DO337: 140 °C, 200 mL air/min
Stir/Titration time: 0/900 s
Newspaper
0.04
6 7.04
0.53
100 mL Coulomat A Evaporate moisture with drying oven
5 mL Coulomat C
DO337: 140 °C, 200 mL air/min
Stir/Titration time: 0/900 s
Insulation
paper
0.05
6 6.41
0.6
100 mL Coulomat A Evaporate moisture with drying oven
5 mL Coulomat C
DO337: 140 °C, 200 mL air/min
Stir/Titration time: 0/900 s
Titration parameters for titrations using DO337 drying oven
Adjustment: control gain: 5; switch-off criterium: fixed titration time and End level 0.05 µg/s
automatic drift determination,manual titration start
Reagents:
Coulomat A:
Coulomat C:
anode reagent HYDRANAL® Coulomat A, Riedel No. 34807
cathode reagent HYDRANAL® Coulomat C, Riedel No. 34808
Comments concerning applications with DL37
The paper samples are cut into pieces of approx. 4–8 cm2. These are placed in the drying oven
sample crucible with tweezers.
The paper should be stored in a closed container under constant conditions. Ambient conditions
(humidity) influence the samples moisture contents considerably.
METTLER, Karl Fischer Applications
41
11. Building Materials and Minerals
General Comments Most minerals and building materials such as cement, plaster of paris and
lime cannot be titrated directly, as the water is chemically bound. A further
hindrance is that oxides or carbonates will undergo a side reaction with
the KF reagents. For these reasons, the water is evaporated in the drying
oven and the vapor then transferred into the KF cell by a dry purge gas.
Zeolites
Zeolites are silicates with a three-dimensional structure composed of SiO4
and AlO4 molecules with characteristically dimensioned canals and hollow spaces. These occur naturally; most, however, are synthetic. They are
used as molecular sieves (for the partitioning of small molecules such as
H2O, NH3, H2S, etc.), ion exchangers (for cations), boiling chips, catalysts (for gas-phase reactions) and as detergents. The zeolites tightly bind
water in the spaces. Water is released stepwise at successively higher
temperatures. The release is complete at 300–350 °C.
References Lindner, B. and Rudert, V., Verbesserte Methode zur Bestimmung von gebundenem Wasser in Mineralien, Gesteinen und anderen Feststoffen,
Fresenius Z. Anal. Chem. 248, 21-24 (1969)
Rechenberg, W., Bestimmung des Wassergehaltes in Zement,
Zement-Kalk-Gips 29, 512-516 (1976)
Farzaneh, A. and Troll, G., Quantitative Methode zur Bestimmung von
Wasser in Mineralien, Gesteinen und anderen Feststoffen,
Fresenius Z. Anal. Chem. 287, 43-45 (1977)
42
METTLER, Karl Fischer Applications
Applications: Building Materials and Minerals
A) Volumetric determination using DL35
Sample
Weight
Result
g
n %
RSD
%
Titrant
Solvent
Method
Plaster of
paris
0.5
6 6.04
0.5
Titrant 9258
40 mL methanol
Evaporate moisture with drying oven
DO302: 300 °C, 200 mL, N2/min
Stir time: 600 s
Knifing filler
0.5
5 5.49
1.2
Titrant 9258
40 mL methanol
Evaporate moisture with drying oven
DO302: 300 °C, 200 mL, N2/min
Stir time: 900 s
Zeolite S90
ground
0.3
6 12.4
0.43
Titrant 9258
40 mL methanol
Evaporate moisture with drying oven
DO302: 300 °C, 200 mL, N2/min
Stir time: 600 s
Reagent:
Titrant 9258:
one component reagent Titrant 5 mg H2O/mL, MERCK No. 9258
B) Coulometric determination using DL37
Sample
Weight
Result
g
n ppm
RSD
%
Reagents
Method
Cement
0.4
2.2
100 mL Anolyte
5 mL Catholyte
Evaporate moisture with drying oven
DO337: 300 °C, 200 mL, N2/min
Stir/Titration time: 0/1200 s
6 0.820
Titration parameters for titrations with DO337 drying oven:
Adjustment: control gain: 5; switch-off criterium: fixed titration time or End level 0.05 µg/s
automatic drift determination, manual titration start
Reagents:
Anolyte:
Catholyte:
anode reagent KF reagent for coulometric water content determination, MERCK No. 9255
cathode reagent KF reagent for coulometric water content determination, MERCK No. 9255
Comments concerning the applications
Plaster of paris Plaster releases the water slowly. A direct titration of the suspension in
solvent is still possible though. After a stir time of 25 minutes, nearly the
same moisture content (5.8 %) was determined using this method as
was obtained with the drying oven (6.0 %).
Knifing filler The filler binds water tightly. The water is not released completely in a direct titration (result of a direct titration with a 75-minutes stir time: 2.4%).
Due to the tight binding of the water, the sample must be heated to 300 °C
for 15 minutes in the drying oven.
Zeolite Zeolite releases water completely at temperatures higher than 300 °C.
Drying temperature: 300 °C, drying time: 10 minutes.
Cement Cement contains CaO which reacts with the KF reagent. Therefore the
moisture is evaporated in the drying oven at 300 °C and the vapor is
transferred into the titration cell using a dry purge gas. The coulometric
method is used due to the low moisture content.
METTLER, Karl Fischer Applications
43
12. Index of Reagents
Reagent
(all pyridine-free)
Riedel-de Haën
HYDRANAL®
E. MERCK
Fluka AG
34801
—
34811
—
34800
34812
9243
—
—
—
9241
9230
60626
—
—
—
60625
—
8844
8842
—
—
8855
—
1604
—
1603
1602
1610
—
—
—
—
9233
—
9221
—
—
—
8844
—
8840
1604
1603
1609
One-component reagent
Titrant 5 mg H2O/mL
Titrant 2 mg H2O/mL
Titrant 1 mg H2O/mL
Anhydrous methanol
34805
34806
34827
34940
9258
—
—
6012
60623
—
—
65546
—
—
—
8047
1600
1601
1606
814/1240
One-component reagent
for ketones and aldehydes
Titrant 5 mg H2O/mL
Titrant 2 mg H2O/mL
Solvent
34816
—
34817
—
—
—
—
—
—
—
—
—
1600
1601
1608
Reagents for coulometric
KF titration
Anolyte
Katholyte
34807
34808
9255
9255
—
—
—
—
1612
1613
Reagents for coulometric
KF titration (for ketones)
Anolyte
Katholyte
34820
34821
—
—
—
—
—
—
1619
—
Titre standards
disodium tartrate dihydrate • 2 H2O
Standard 5 mg H2O/mL
Standard 1 mg H2O/mL
Methanol 5 mg H2O/mL
34803
34813
34828
34802
6664
9259
—
—
71994
—
—
—
0317
—
—
—
805
1617
1618
—
Standards for
pH-adjustment
Buffer 5 mmole acid/mL
Benzoic acid
Salicylic acid
Imidazole
34803
18102
27301
63561
—
136
635
4716
—
12349
84210
56750
—
1270
0251
1747
1615
673
799
—
Auxiliary solvents
Chloroform
Methanol
1-Dodecanol
1-Propanol
Toluene
Formamide
32286
32213
62411
33538
32249
62608
2445
6009
803463
997
8325
9684
25690
65546
30610
82090
89681
47670
9257
8047
—
8397
8078
7042
816/1234
814/1240
—
—
1052/1245
1093
unnecessary
ME-23774
ME-23817
unnecessary
unavailable
Two-component reagent
Titrant 5 mg H2O/mL
Titrant 3,5 mg H2O/mL
Titrant 2 mg H2O/mL
Titrant 1 mg H2O/mL
Solvent
Solvent for fats and oils
Two-component reagent
for ketones and aldehydes
Titrant 5 mg H2O/mL
Titrant 2 mg H2O/mL
Solvent
Bottle adaptore METTLER
44
J.T. Baker Ericsen/GFS
METTLER, Karl Fischer Applications
Index of Suppliers
Riedel-de Haën AG
Headquarters:
Wunstorfer Strasse 40
Postfach
D-3016 Seelze
Tel. (0 51 37) 7 07 0
Telefax (0 51 37) 9 19 79
E. MERCK
Headquarters:
Postfach 4119
D-6100 Darmstadt 1
Frankfurter Strasse 250
Tel. (06151) 72 0
Telefax (06151) 72 33 68
Fluka AG
J. T. Baker
Ericsen/GFS
Headquarters:
Fluka Chemie AG
Postfach 172
CH-9470 Buchs
Industriestrasse 25
Tel. 085 6 95 11
Telefax 085 6 54 49
Headquarters:
J. T. Baker Inc.
222 Red School Lane
Phillipsburg
N.J. 08865
Tel. 908-8592151
Telefax 908-859 2865
Headquarters:
GFS Chemicals
P.O. Box 245
Powell
OH 43065
Tel. (US) 800-858-9682
Tel. (outside US) 614-881-5501
Telefax 614-881-5989
METTLER, Karl Fischer Applications
45
13. Hazards and waste disposal tips
One-component reagent
Contains: sulfur dioxide, iodine, base (imidazole) and solvent (methanol,
2-methoxyethanol or diethyleneglycolmonomethylether).
Safety precautions: flammable to extremely flammable. Irritant when inhaled. Health hazard when
inhaled, swallowed or allowed to contact skin. Keep container tightly closed. Keep away from open
flames or sparks. Do not let reagent contact skin or eyes.
Disposal: as an organic solvent.
Two-component reagent:
This titrant contains: iodine and solvent (methanol, 2-methoxyethanol, xylene or trichloroethylene).
The KF-solvent contains: sulfur dioxide, base (imidazole) and solvent (methanol,
2-methoxyethanol or diethyleneglycolmonomethylether).
Safety precautions: flammable to extremely flammable. Irritant when inhaled. Health hazard when
inhaled, swallowed or allowed to contact skin. Keep container tightly closed. Keep away from open
flames or sparks. Do not let reagent contact skin or eyes.
Disposal: as an organic solvent.
Reagents for coulometry:
This reagent contains iodide, sulfur dioxide, base (imidazole), and solvent (methanol, chloroform,
tetrachloromethane, 2-methoxyethanol).
Safety: Highly flammable. Skin irritant. Poisonous when inhaled or swallowed. Keep container tightly
closed and far removed from open flames or sparks. Do not let reagent contact skin or eyes.
Disposal: as an organic solvent.
Safety data for the KF-components and auxiliary solvents:
sulfur dioxide: MAK-value: 200 ppm
iodine: MAK-value: 0.1 ppm, oxidant
diethyleneglycolmonomethylether: Flashpoint: 87 °C
2-methoxyethanol: Flashpoint: 46 °C, MAK value: 5 ppm
Flammable. Potential teratogen.
Health hazard when inhaled, swallowed or allowed to contact skin.
Irritant when inhaled.
methanol: Flashpoint: 11 °C, MAK value: 200 ppm
Highly flammable. Poisonous when inhaled or swallowed.
o-xylene: Flashpoint: 28 °C, MAK value: 100 ppm
Flammable. Health hazard upon inhalation.
chloroform: Flashpoint: does not burn, MAK value: 200 ppm
Health hazard when inhaled. Irreversible damage possible.
1-decanol: Flashpoint: 95 °C, Irritant for skin and eyes.
formamide: Flashpoint: does not burn, MAK value: 20 ppm
Irritant for skin and eyes. Potential teratogen.
toluene: Flashpoint: 6 °C, MAK value: 20 ppm
Extremely flammable. Health hazard upon inhalation.
46
METTLER, Karl Fischer Applications
14. Sample Index
Acetaldehyde
Acetic acid
Acetone
Acetonitrile
Acetophenone
Acrylic paint
Adhesives
Agrochemicals
Aluminum oxide
Aluminum powder
Aniline
Antibiotics
Aspirin
Benzaldehyde
Benzamide
Benzyl alcohol
Brake fluid
Calcium chloride
Calcium oxide
Cellulose
Cement
Chamomile extract
4-Chlorotoluene
Cleaner liquid
Cough drops
Crude oil
Cyanoacryl glue
Cyclohexene
Detergents
Diesel oil
Diethylether
Dimethylformamide
Dish detergent
Disinfectant
Dispersion dye
Dyes
Epoxy resin
Ethylene glycol
Ethyl acetate
Ethylen chloride
Eucalyptus oil
Fabric softener
Fats
Fungicide
Gasoline
Gel for sprains
16,18
16
16,18
16
10,12
36
27–30
35–37
6
6,8
10,12
32
32
10,12
12
10,12
24
6
6
41
43
32
10,12
39
32
22,24,26
28
16,18
38–39
22
16,18
16,18
39
32
36
35–37
28
16,18
18
18
34
39
21–25
35,37
22,24
32
METTLER, Karl Fischer Applications
Glue stick
Grease
Herbicide
Hydraulic oil
Impregnation agent
Indicator dye
Insecticide
Insulation paper
iso-Amyl alcohol
Isobutylmethylketone
Isopropyl alcohol
Kerosene
Knifing filler
Laundry detergent
Liquid detergent
Lithium chloride
Lyophilized Plasma
Magnesium oxide
Massage oil
Medicines
Methyl benzoate
Methylene chloride
Mineral oil
Minerals
Motor oil
n-Butylamine
n-Hexane
Naphtaline
2-Nitrophenol
Non-ionic surfactant
Ointment
Optical brightener
Oxalic acid
Paint
Paper
Paraffin
Petroleum
Petroleum Products
Phenol
Phosphoric acid
Plaster of paris
Plastics
Polyamide
Polyethylene
Polypropylene
Polystyrene
28
22
36
24
39
36
36
41
16
16,18
18
24
43
39
39
6
34
6
34
31–33
10,12
16
21–25
43
22
10,12
18,20
12
10
39
32
36
10
36
41
24
22,24
21–25
12,14
6
43
27–30
28
28,30
28
28
PVC
Reactive dye
Rubber cement
Salicylic acid
Shoe polish
Silicon oil
Silk
Skiwax
Sodium carbonate
Sodium chloride
Soft soap
Soot
Sulfuric acid
Suppository
Surfactants
Synthetic enamel
Tonic
Toluene
Transformer oil
Turbine oil
Urea
Valerian essence
Waxes
Wood
Wool
Wool dye
Zeolite
28
36
28
10,12
22
22,24
41
22
6
6
39
24
6
32
38–39
36
32
16,18
24
24
10
32
21–25
41
41
36
43
47
Notes
48
METTLER, Karl Fischer Applications
Notes
METTLER, Karl Fischer Applications
49
Notes
50
METTLER, Karl Fischer Applications
This application bulletin represents selected, possible application examples. These have been tested with all
possible care in our lab with the analytical instrument mentioned in the bulletin. The experiments were
conducted and the resulting data evaluated based on our current state of knowledge.
However, the application bulletin does not absolve you from personally testing its suitability for your intended
methods, instruments and purposes. As the use and transfer of an application example are beyond our control,
we cannot accept responsibility therefore.
When chemicals and solvents are used, the general safety rules and the directions of the producer must
be observed.
METTLER, Karl Fischer Applications
51
Mettler-Toledo GmbH
Analytical
CH-8603 Schwerzenbach, Schweiz
Telefon (01) 806 77 11, Fax (01) 806 73 50
Internet: http://www.mt.com
AT Mettler-Toledo GmbH., A-1100 Wien
Tel. +43-1-604 19 80, Fax +43-1-604 28 80
AU Mettler-Toledo Ltd., Port Melbourne, Victoria 3207
Tel. +61-3-9644 5700, Fax +61-3-9645 3935
BE N.V. Mettler-Toledo S.A., B-1932 Zaventem
Tel. +32-2-334 02 11, Fax +32-2-334 03 34
CH Mettler-Toledo (Schweiz) AG, CH-8606 Greifensee
Tel. +41-1-944 45 45, Fax +41-1-944 45 10
CN Mettler-Toledo (Shanghai) Ltd., Shanghai 200233
Tel. +86-21-6485 0435, Fax +86-21-6485 3351
CZ Mettler-Toledo, spol, s.r.o., CZ-12000 Praha 2
Tel. +420-2-25 49 62, Fax +420-2-2424 7583
DE Mettler-Toledo GmbH, D-35353 Giessen
Tel. +49-6-41 50 70, Fax +49-6-41 507 128
DK Mettler-Toledo A/S, DK-2600 Glostrup
Tel. +45-4327 0800, Fax +45-4327 0828
ES Mettler-Toledo S.A.E., E-08038 Barcelona
Tel. +34-3-223 22 22, Fax +34-3-223 02 71
FR Mettler-Toledo s.a., F-78222 Viroflay
Tel. +33-1-3097 1717, Fax +33-1-3097 1616
HK Mettler-Toledo (HK) Ltd., Kowloon
Tel. +852-2744 1221, Fax +852-2744 6878
HR Mettler-Toledo, d.o.o., HR-10000 Zagreb
Tel. +385-1-230 41 47, Fax +385-1-233 63 17
HU Mettler-Toledo, KFT, H-1173 Budapest
Tel. +36-1-257 70 30, Fax +36-1-256 21 75
IT Mettler-Toledo S.p.A., I-20026 Novate Milanese
Tel. +39-2-333 321, Fax +39-2-356 29 73
JP Mettler-Toledo K.K., Osaka 540-6017
Tel. +81-6-949 59 01, Fax +81-6-949 59 45
KR Mettler-Toledo (Korea) Ltd., Seoul (135-090)
Tel. +82-2-518 20 04, Fax +82-2-518 08 13
KZ Mettler-Toledo CA, 480009 Almaty
Tel. +7- 3272-608 834, Fax +7-3272-608 835
MY Mettler-Toledo (M) Sdn. Bhd. 47301 Petaling Jaya
Tel. +60-3-703 27 73, Fax +60-3-703 17 72
MY Mettler-Toledo (S.E.A.), 47301 Petaling Jaya
Tel. +60-3-704 17 73, Fax +60-3-703 17 72
MX Mettler-Toledo S.A. de C.V., México C.P. 06430
Tel. +52-5-547 57 00, Fax +52-5-541 22 28
NL Mettler-Toledo B.V., NL-4000 HA Tiel
Tel. +31-3-4463 8363, Fax +31-3-4463 8390
PL Mettler-Toledo, Sp. z o.o., PL-02-929 Warszawa
Tel. +48-22-651 92 32, Fax +48-22-651 71 72
RU Mettler-Toledo C.I.S. AG, 10 1000 Moscow
Tel. +7-095-921 92 11, Fax +7-095-921 63 53
SE Mettler-Toledo AB, S-12008 Stockholm
Tel. +46-8-702 50 00, Fax +46-8-642 45 62
SG Mettler-Toledo (S) Pte. Ltd., Singapore 139944
Tel. +65-7786 779, Fax +65-7786 639
SK Mettler-Toledo, SK-82104 Bratislava
Tel. +421-7-4342 7496, Fax +421-7-4333 7190
SI Mettler-Toledo, d.o.o., SI-1236 Trzin
Tel. +386-61-162 18 01, Fax +386-61-162 17 89
TH Mettler-Toledo (Thailand) Ltd., Bangkok 10310
Tel. +66-2-719 64 80, Fax +66-2-719 64 79
TW Mettler-Toledo Pac Rim AG, Taipei
Tel. +886-2-2579 5955, Fax +886-2-2579 5977
UK Mettler-Toledo Ltd., Leicester, LE4 1AW
Tel. +44-116-235 70 70, Fax +44-116-236 63 99
US Mettler-Toledo, Inc., Columbus, OH 43240
Tel. +1-614-438 4511, Fax +1-614-438 4900
For all other countries:
Mettler-Toledo GmbH
PO Box, VI-400, CH-8606 Greifensee, Schweiz
Tel. (01) 944 22 11, Fax (01) 944 31 70
Subject to technical changes
© 09/04 Mettler-Toledo GmbH, ME-00724354
Printed in Switzerland on 100% chlorine-free
paper, for the sake of our environment.