International Summer Water Resources Research SchoolDept. of
Water Resources Engineering, Lund University
Determination of Total Phosphorus
using Sodium Persulfate
Manuela Stierna Fernandez
7/17/2015
Figure 1 From right Wang Shu, Yuan Yuan , Fangrui Liu and Manuela Stierna Fernandez
Professor: Jian Ma
Research assistant: Yuan Yuan and Shu Wang
Students: Fangrui Liu and Manuela Stierna Fernandez
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International Water Summer Resources Research School 2015
1. Abstract
This project focuses on the determination of Total Phosphorus (TP) using sodium persulfate
as the oxidative reagent. The determination of TP is an important issue for environmental
science and engineering as it is directly related to eutrophication and algal bloom. Potassium
persulfate is the oxidative regent used in the current method for the determination of TP.
However sodium persulfate is more soluble and less expensive than potassium persulfate and
therefore it has been tested as the substitute of potassium persulfate in this project.
In order to derive this hypothesis the concentration of TP was determined for 30 different
samples using both reagents. Both phosphorus samples and water samples were studied
coming from different locations, time periods and temperatures. A COD digester was used to
convert the TP to inorganic phosphorus. Then this inorganic phosphorus was transformed
using the phosphomolybdenum blue method into heteropoly compound. The absorbance of
this compound was measured using a spectrophotometer. Finally comparing the results in a
calibration curve the concentration of TP was determined. All results were summarized in a
1:1 diagram comparing sodium persulfate and potassium persulfate. The accuracy of this
diagram was calculated using a student t- test and determining the relative standard deviation.
The results using both reagents had non-significant difference. Therefore the conclusion was
that the determination of TP could be performed using sodium persulfate as the oxidative
reagent, in other words the hypothesis was correct. Nevertheless these results would have
been more accurate if more data would have been studied.
2. Keywords
Total Phosphorus, sodium persulfate, potassium persulfate, phosphomolybdenum blue
method, eutrophication and algal bloom.
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Table of Contents
1.
Abstract .............................................................................................................................. 1
2.
Keywords ........................................................................................................................... 1
3.
Introduction and Hypothesis .............................................................................................. 3
4.
Methodology and Theory ................................................................................................... 3
4.1
Apparatus ..................................................................................................................... 3
4.1.1. Phosphomolybdenum blue method .......................................................................... 3
4.1.2. Digestion .................................................................................................................. 4
4.1.3. Spectrophotometer ................................................................................................... 4
4.1.4Calibration curve ........................................................................................................ 5
4.1.5 Test of Significance ................................................................................................... 5
4.1.6 Relative standard deviation (RSD) ............................................................................ 6
4.2 Reagents and standards .................................................................................................... 7
4.2.1. Phosphorus ............................................................................................................... 7
4.2.2. Potassium persulfate ................................................................................................. 7
4.2.3. Sodium persulfate ..................................................................................................... 8
4.3
5
Procedure ..................................................................................................................... 8
Results .............................................................................................................................. 10
5.1
Phosphorus samples ................................................................................................... 10
5.2
Water samples............................................................................................................ 10
5.3
Calibration curves inclinations .................................................................................. 11
5.4 Relation between TP concentrations determined using sodium and potassium persulfate.
.............................................................................................................................................. 12
5.5 Test of Significance ........................................................................................................ 12
5.6 Relative standard deviation (RSD) ................................................................................. 13
6
Discussion ........................................................................................................................ 13
7
Conclusion ........................................................................................................................ 15
7.1Future recommendations ................................................................................................. 15
8. Acknowledgements .............................................................................................................. 16
9. References ............................................................................................................................ 17
10. Appendix ............................................................................................................................ 18
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3. Introduction and Hypothesis
Eutrophication and algal bloom are both worldwide problems. These issues are related to the
concentration of Total Phosphorus (TP) present in both terrestrial and aquatic environments.
Therefore the determination of TP is an important analysis that can be performed for several
reasons: water pollution, biological and chemical studies and eutrophication.
The current method used for the determination of TP utilizes potassium persulfate in order to
oxidize TP to phosphate. This project was performed with the hypothesis that sodium
persulfate could be used as the oxidative reagent in the determination of TP. This hypothesis
was formulated after comprehensive evaluation of sodium persulfate. If the hypothesis is
correct the determination of TP could be performed more convenient and cheaper since
sodium persulfate is more soluble and less expensive than potassium persulfate.
The determination of TP was performed with the classical phosphomolybdenum blue method
and the usage of a calibration curve. ACOD digester utilizing conventional heating was used
in order to convert the TP to inorganic phosphorus. This chemical process was necessary in
order to determine the absorbance of the phosphorus in a spectrophotometer. The accuracy of
the results was determined with the test of significance and the relative standard deviation
(RSD).
4. Methodology and Theory
4.1 Apparatus
4.1.1. Phosphomolybdenum blue method
The concentration of TP was determined with the phosphomolybdenum blue method, which is
the most widely used. The chemistry is based on the reaction of orthophosphate with
molybdenum under acidic condition to form 12-molybdophosphoric acid, which is usually
then reduced to a blue heteropoly compound (Burton, 1973). The blue heteropoly compound
is further used to determine the absorbance of the TP present in a sample utilizing a
spectrophotometer.
Ascorbic acid, C6H8O6, was the reductant used to reduce12-molybdophosphoric acid. The
following acid has been shown to possess both theoretical and practical advantages in the
presence of antimonyl ions according to Burton, 1973. Ammonium molybdate mixture was
then used to create the blue color in the sample. In order to reach a minimum reaction time
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the molybdate mixture had to be higher than 25% of the stock mixed reagent and the ascorbic
acid concentration had to be higher than 25 g/L as stated by Ma et.al, 2014.
4.1.2. Digestion
In order to determine the absorbance of TP a COD digester was utilized. This apparatus
breakdowns the organic phosphorus and convert it to inorganic phosphorus, most likely
orthophosphate. The digestion reaction followed by the phosphomolybdenum blue method is
determined by the following equation (Mather et.al, 1998):
3−
3−
𝑃𝑂3− + 12𝑀𝑜𝑂42− → 𝑃𝑀𝑜12 𝑂40
+ 12𝑂2− → 𝑃𝑆𝑏2 𝑀𝑜𝑂10 𝑂40
𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 1
The conventional heating was the type of COD digester used
for this experiment. The digestion was therefore obtained with
high pressure inside the digestion tubes which increased with
higher temperature. The temperature in the digestion was 150
℃ and the reaction time was 15 minutes.
A disadvantage with the conventional heating is that
precipitation of salts may occur which causes problems when
analyzing phosphorus with the phosphomolybdenum blue
method, as studied by Huang et.al, 2008.
Figure 2 COD digester used during the
laboratory experiments
4.1.3. Spectrophotometer
A spectrophotometer was used to determine the absorption of the diluted inorganic
phosphorus which is related to its concentration. Since the spectrophotometer only analyzes
the wavelengths of inorganic phosphorus digestion was needed to convert TP to inorganic
phosphorus.
This apparatus is composed by a spectrometer
which produces light of any selected color
dependent on its wavelength and a photometer
which measures the intensity of the light. This
reaction is described by Beers law as following:
𝐼
= 10 ∗ 𝑘 ∗ 𝑐 = 𝑇
𝐼0
Figure 3 Spectrophotometer used during the laboratory
experiments
𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 2
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I0=the intensity of the transmitted light
I= the intensity of the transmitted light when the colored compound is added
c = the concentration of the colored compound, phosphorus
k= constant relate to the distance the light passes through the solution
T = the transmittance of the solution.
The Logarithmic equation for the above equation studies the optical density which is
proportional to the phosphorus concentration and is measured in absorbance units:
− 𝑙𝑜𝑔(𝑇) =
𝑙𝑜𝑔(1)
= 𝑘𝑐 = 𝑜𝑝𝑡𝑖𝑐𝑎𝑙 𝑑𝑒𝑛𝑠𝑖𝑡𝑦
𝑇
𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 3
The absorbance used in this research was 700 nm with a 1 cm cuvette under the condition of
wavelength 1 cm using water as reference solution.
Since the colorimetric method used was the phosphomolybdenum blue method the samples
were blue. Therefore the wavelength for the red color was the one studied by the
spectrophotometer which was proportional to the concentration of the inorganic phosphorus
present in the analyzed sample.
4.1.4Calibration curve
A calibration curve was calculated in order to determine the relation between different
concentration of TP and its absorbance. The phosphomolybdenum blue method and a
spectrophotometer were used to determine the absorbance of the known concentrations. The
results were then linearized and the accuracy was determined by R2 which had to be higher
than 0.99.
The purpose of the calibration curve was to
determine the final concentration of the TP present
in the different samples by knowing its absorbance.
To achieve accurate results a new calibration curve
was performed for each laboratory experiment.
Figure 4 Calibration cuvettes used during the
laboratory experiments
4.1.5 Test of Significance
The Student t- test was utilized to analyze the difference between the TP concentration results
obtained using potassium persulfate or sodium persulfate. The hypothesis was that both
methods were identical. With other words we compared the results of a new analytical method
with an accepted method in order to determine its accuracy.
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The calculations were based on a statistical t- value that was compared with a tabulated value
for the given results. If the t-value was lower than the tabulated value the methods did not
have any significant error and were therefore identical.
The equation used to calculate the t-value when comparing the means of two methods was the
following (Garry et.al, 2014):
𝑡𝑐𝑎𝑙𝑐 =
̅̅̅
𝑥1 − ̅̅̅
𝑥2
𝑁1𝑁2
√
𝑠𝑝
𝑁1 + 𝑁2
𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 4
Where ̅̅̅
𝑥1 and ̅̅̅
𝑥2 were the means of the results, N1 and N2 were the number of samples
measured in each method and sp was the pooled standard deviation.
The pooled standard deviation, sp, was determined with the following equation (Garry et.al,
2014):
∑(𝑥𝑖 − 𝑥1 )2 + ∑(𝑥𝑖2 − 𝑥2 )2 + ⋯ + ∑(𝑥𝑖𝑘 − 𝑥𝑘 )2
√
𝑠𝑝 =
𝑁−𝑘
𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 5
Where x1,x2,xk were the means of each set of analysis, xi1,xi2,xik were the individual values of
each set and N was the total value of measurements.
The student t- test was performed in Excel with a 95% confident. In Excel, to acquire a nonsignificant difference in the result the tcalc had to be lower than the critical two tailed value.
4.1.6 Relative standard deviation (RSD)
During the laboratory experiments each phosphorus sample and water sample was analyzed
three times. Therefore the relative standard deviation was calculated in order to study the
probable error of the results. The equation used was the following:
𝑅𝑆𝐷 =
𝑠
∗ 100
𝑥
𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 6
Where x was the mean of the three results and s was the estimated standard deviation
calculated with the below equation:
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∑(𝑥𝑖 − 𝑥)2
√
𝑠=
𝑁−1
𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 7
4.2 Reagents and standards
4.2.1. Phosphorus
Phosphorus is an important nutrient for living organisms in both terrestrial and aquatic
environments. It could be presented as the limiting nutrient in marine environment
compromising photosynthesis. Nevertheless phosphorus can be an excessive nutrient, related
to water pollution, causing eutrophication and algal bloom.
Phosphorus compounds present in natural water are classified into four groups according to
Mather et.al, 1998. These compounds may contain PO3−
4 , P-O-P, C-O-P and C-P bonds:

Orthophosphates

Condensed Phosphates

Organically bound Phosphates

Phosphonates
The majority of the inorganic phosphorus is dominated by ortophosphoric acid which has an
important effect on the phosphorus cycling. This effect has been highly studied in many
papers.
On the other hand, papers studying the role of organic phosphorus in aquatic biogeochemical
and ecological processes are far less advanced as stated by Baldwin, 2013.However it has
been studied that organic phosphorus is an important pool of phosphorus in many aquatic
environments and its effect on the phosphorus cycling globally is also significant. There are
seven types of organic phosphorus as studied by Worsfold et.al, 2008: nucleic acids,
phospholipids, inositol phosphates, phosphoamides, phosphoproteins, sugar phosphates,
amino phosphoric acids and organic condensed Phosphorus species.
4.2.2. Potassium persulfate
Potassium persulfate is a white solid inorganic compound with the chemical formulaK2 S2 O8 .
It has been extensively used for the determination of TP as it has proved suitable for a wide
range of samples as stated by Burton, 1973. On the other hand potassium persulfate has lower
solubility and a higher price than sodium persulfate. Therefore in this experiment sodium
persulfate has also been used for the determination of TP concentration.
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4.2.3. Sodium persulfate
Sodium persulfate is an inorganic compound with the chemical formula Na2 S2 O3 . It is a white
solid with a higher solubility and a lower price compared to potassium persulfate. It has not
been used before for the determination of TP.
4.3 Procedure
The aim of this experiment was to compare the concentration of TP present in different
phosphorus and water samples using sodium persulfate and potassium persulfate. The
following procedure was performed for 30 samples in order to reach accurate results. The
different phosphorus and water samples are presented in table 2 and 3 respectively.
1. During each laboratory day a new calibration curve was performed for several
concentrations of phosphorus. The concentrations were diluted into 25 mL distillated water.
Then 0.5 mL of ascorbic acid and 1 mL of ammonium molybdate mixture were added to
create a blue color to the diluted volumes. As the color was blue the spectrophotometer
studied the absorbance of the red light. The absorbance was calculated with a 1 cm cuvette
under the condition of wavelength 1 cm, 700 nm, and using distillated water as reference
solution.
An example of a calibration curve calculated is presented below:
Table 1Example Calibration curve for phosphorus concentrations
Absorbance (A)
Concentration(𝛍mol/L) 0
0
Absorbance
0,7
0,6
0,5
0,4
0,3
0,2
0,1
0
1
0.025
2
0.05
4
0.086
8
0.155
16
0.306
32
0.635
y = 0,0196x + 0,0035
R² = 0,9992
0
5
10
15
20
25
30
35
Concentration TP (umol/L)
Figure 5 Example Calibration curve
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2. The digestion was then performed to transform the TP, present in the samples, into
inorganic phosphorus. When studying phosphorus samples 0.5 mL of three phosphorus types
were mixed three times with 2 mL sodium persulfate and three times with 2 mL potassium
persulfate, in total 18 tubes. When using water samples, 5 mL of two samples were mixed
three times with 5 mL sodium persulfate and three times with 5 mL potassium persulfate, in
total 12 tubes.
These tubes were then digested for 15 min in a COD digester with a temperature of 150 ℃.
After taking them out and cool, 2.5 mL of each solution was transferred to a 25 mL
colorimetric tube.
Then 0.5 mL of ascorbic acid and 1 mL of ammonium molybdate were added to each tube
and the absorbance was calculated with a 1 cm cuvette under the condition of wavelength 1
cm, 700 nm, and using distillated water as reference solution.
3. After calculating the absorbance, the concentration of the TP was calculated using the
equation of the calibration curve. This procedure was performed assuming that all TP had
transformed to inorganic phosphorus during the digestion.
Example calibration curve equation: y = 0.0196x + 0.0035
y= absorbance of the TP using potassium persulfate/ sodium persulfate.
x=concentration of the TP using potassium persulfate/ sodium persulfate
4. Different sources of error appear during the experiment:

The digestion tubes were not perfectly closed when entering the COD digester. As a
consequence some of the solutions had evaporated with the high temperature.

When utilizing the phosphomolybdenum blue method the absorbance was too fast
determined even though the blue color did not totally develop.
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5 Results
5.1 Phosphorus samples
The following table studies fifteen different phosphorus samples analyzed during the
laboratory experiment. Each phosphorus sample is presented with its name, chemical formula
and concentration.
Table 2 Phosphorus samples information
Phosphorus samples
Sodium Phosphonoformate hexahydrate
Riboflavin-5-phosphate sodium salt dehydrate
CH12Na2O11P ,0.305 g/L
0.45 g/L
Phenyl phosphate disodium salt dehydrate
Adenosine-5-monophosphoric acid
C6H5Na2O4P, 1mmol/L
C10H14N5O7P 980 mol/L
Sodium peryphosphate Na4P2O7, 0.05g/L
Sodium trypolyphosphate Na5P3O10 946 mol/L
2-deoxyadenosine 5-dihydrogen phosphate
Glycerol phosphate disodium salt
C10H14N5O6P, 0.153 g/L
hydrate C3H7Na2O6P, 0.212 g/L
Glycerophosphoric acid C3H9O6P 0.66 g/L
4-nitrophonyl phosphate disodium salt hexahydrate
O2NC6H4OP(O)(ONa)2, 0.342 g/L
Phosphonoacetic acid C2H5O5P, 0.132 g/L
5-ciuanylic acid, 0.410 g/L
α-sodium Glycerophosphate C3H7Na2O6P ,0.216
Beta-D-glucose 6-phosphate sodium salt anhydrous
g/L
C6H12NaO9P, 0.268 g/L
Adenosine triphosphate C10H16N5O13P3, 1395
mol/L
5.2 Water samples
Table 3 shows fifteen water samples analyzed during the laboratory experiments. These
samples were taken from different locations (lake, river water, industry, irrigation, seawater
and tap water) at different time and temperature. All samples were located in the Xiamen area.
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Table 3 Water samples information
Water samples
Lake, Xiamen University
River water
River water
River water
River water M8
River water
River water
M5 24.8℃
M6 24.5℃
M7 25.5℃
25.1℃
M9 26℃
M11
2015/06/27
2015/06/27
2015/06/27
2015/06/27
2015/06/27
25.1℃
2015/06/27
Industry pesticide filtered Xiamen 0,5 ml
Industry pesticide filtered Xiamen 2 ml
Irrigation water, Xiamen University
Coastal Area in Xiamen S5
Tap water 1
Coastal Area in Xiamen S6
Coastal Area in Xiamen S4
Tap water 2
5.3 Calibration curves inclinations
The diagram below presents the inclinations of nine different calibration curves performed
during nine laboratory days. The lowest inclination was 0.138 and the highest was 0.197.
With other words, the largest difference between the inclinations of the different calibration
curves was 0.059.
Calibration curve incline
Inclination
0,02
0,015
0,01
Calibration curve incline
0,005
0
1
2
3
4
5
6
7
8
9
Daily Calibration Curve
Figure 6 Calibrations curves in different days.
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5.4 Relation between TP concentrations determined using sodium and potassium
persulfate.
The following diagram presents the TP concentration presented in the phosphorus samples
and the water samples using sodium persulfate or potassium persulfate. These results were
presented in a 1:1 line where the TP concentrations using sodium persulfate equals the TP
concentrations using potassium persulfate.
Seven different kinds of samples were described in the legend. The lowest TP concentration
was 3.13 μmol/L and the highest concentration was 2192 μmol/L. All the data for the
following diagram is presented in table 7 and 8 located in the appendix.
Total Phosphorus concentration using sodium
persulfate (umol/L)
3500
3000
2500
Phosphorus samples
Spring Lake
2000
Irrigation water
River water
1500
Industry water
Costal area water
1000
Tap water
500
Linear (K=Na 1:1)
0
0
500
1000
1500
2000
2500
3000
3500
Total Phosphorus concentration using potassium persulfate (umol/L)
Figure 7 Relation between TP concentrations determined using sodium and potassium persulfate.
5.5 Test of Significance
Table 4 and 5 shows the t statistic and the t critical two-tailed value obtained when
performing the test of significance for the phosphorus samples and the water samples. The
calculations were performed in excel.
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Table 4 T- test for the phosphorus samples
Test of Significance for phosphorus samples
t Statistic
0.1645
t Critical two-tailed
2.04
Table 5 T-test for the water samples
Test of Significance for water samples
t Statistic
0.007972
t Critical two-tailed
2.04
5.6 Relative standard deviation (RSD)
The relative standard deviation calculations are presented in table 6 situated in the appendix.
In order to calculate the RSD the standard deviation and the average were calculated for all
concentrations of TP analyzed during the laboratory experiments. The calculations were
performed in excel.
6 Discussion
The aim of this paper was to determine if the determination of TP could be performed using
sodium persulfate as the oxidative reagent instead of potassium persulfate. In order to derive
this hypothesis the concentration of TP was determined for 30 different samples using both
sodium persulfate and potassium persulfate.
The TP concentrations from the 30 samples were gather in Figure 7 around a 1:1 line where
the results using sodium persulfate equals the one using potassium persulfate. When
analyzing this Figure we can conclude that the determination of TP was very similar using the
two different oxidative reagents as nearly all concentrations were situated near or in the 1:1
line.
This statement was proved with the student t-test performed for both the phosphorus samples
and the water samples. The results were presented in table 4 and 5. In order to achieve a nonsignificant difference the t-statistic had to be lower than the t-critical two tailed. This was the
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case for both the phosphorus samples where the t-statistic was 12 times lower than the tcritical two tailed and for the water samples were the t-statistic was 255 times lower than the
t-critical two tailed. In other words, this proves that there was no significant different in the
determination of TP using sodium persulfate instead of potassium persulfate.
On the other hand when looking at Table 7 and 8, located in the appendix, we can study that
for some samples there was a higher difference between the TP concentrations calculated with
sodium persulfate and the ones calculated with potassium persulfate. The reason for this
difference could be that after digestion all the chemical compound was not pore down in the
phosphomolybdenum blue cuvettes. As a consequence the absorbance studied for these
samples was lower than expected. Another reason could be that sodium persulfate is not an
accurate oxidative reagent for all types of samples and therefore it has not been used in earlier
studies.
Since each sample was performed three times the RSD was calculated for each three samples.
These calculations were done in order to be confident about the accuracy of the results. Table
6, situated in the appendix, presents the standard deviation, the average and the RSD for each
phosphorus samples and water samples. According to Garry et.al, 2014 if the RSD is lower
than 10% the results have non-significant difference from each other. Studying Table 6 we
can conclude that all the samples despite three had non-significant difference and were
therefore accurate results. The reason why three samples had a higher RSD than 10 could be
that the TP concentrations calculated were to low making it difficult to calculate the
difference between them.
The 30 samples were taken from different locations at different temperature and time as
presented in Table 2 and 3. As explained above the results showed that the determination of
TP can be calculated using sodium persulfate instead of potassium persulfate. Nevertheless
these results would have been more accurate if more data would have been studied and if the
samples would have been taken from more locations. As an example we could have studied
samples from different soil types where the phosphorus concentration is high.
Figure 6 shows the calibration curve inclination for nine laboratory experiment. A new
calibration curve was performed each day in order to achieve the best results possible.
Studying Figure 6 we can conclude that all inclinations were closed to each other meaning
that similar results were calculated. The highest difference between the inclinations was 0.059
which can be accepted for trace analysis.
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One assumption made during the digestion was that all TP present in the samples was
converted to inorganic phosphorus. This may not have been the case; therefore it would have
been interesting to calculate the efficiency of the digestion. Different types of digestion could
also have been studied in order to increase the accuracy.
7 Conclusion
From the results and discussion it was concluded that the determination of TP can be
performed using sodium persulfate. In other words the experiment was successful and the
hypothesis was correct. The reason why some samples matched better with the hypothesis
than others could be due to human errors during the laboratory experiments or due to the fact
that sodium persulfate do not have the same oxidative effect on all samples.
This project was the first one analyzing sodium persulfate for the determination of TP. The
reason why sodium persulfate was chosen was that it is less expensive and more soluble than
potassium persulfate. Therefore this report has given the possibility to save money in future
work related with the determination of TP.
7.1Future recommendations
These results would have been more accurate if more data would have been studied and if the
samples would have been taken from more locations. Also it would have been interesting to
calculate the efficiency of the digestion and utilize different types of digestion.
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8. Acknowledgements
First of all I would like to thank Professor Jian Ma for preparing this very well planned and
interesting project and for all the help and guidance given to me. Then I would like to thank
my two research assistants Yuan Yuan and Shu Wang for all the work performed in order to
make the laboratory experiments easy and all the kind explanations. I would also want to
thank my student partner Fangrui Liu for all work performed together. Then I would like to
thank all the persons that made this cooperation between Lund University and Xiamen
University possible such as Professor Linus Chang. I also want to thank all the Swedish and
Chinese students that have been part of the summer research school making it a wonderful
stay. Last I would like to thank our sponsor Tyréns to contributing to funding the expenses of
this stay.
Thank you
Figur 8 From right Wang Shu, Fangrui Liu, Manuela Stierna, Yuan Yuan and Qipei Shangguan
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9. References
Baldwin D.S, (2013), Organic Phosphorus in the aquatic environment, La Trobe University,
Vol 2013, pp 439-454.
Burton J.D, ((1973), Problem in the analysis of phosphorus compounds, University of
Southampton, Vol l7, pp291-307,
Crouch S.R. & Malmstad H.V, (1967), A Mechanism Investigation of Molybdenum Blue
Method for Determination of Phosphate, University of Illinois.
Garry D.C & Purnendu K.D & Schug K.A , (2014), Analytical Chemistry, Wiley, Seventh
Edition, United Stated of America.
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17
VVRF05
Manuela Stierna Fernandez
International Water Summer Resources Research School 2015
10. Appendix
Table 6 Relative standard deviation calculations for all the samples performed during the
experiment
TP,K
Std
Av
Av+std
RSD
TP,Na
0,03
0,33
0,36
10,02
0,30
0,30
Std
Av
Av+Std
RSD
0,31
0,0045
0,30
0,31
1,47
0,31
0,35
0,30
0,27
0,27
0,014
0,28
0,29
4,98
0,29
0,30
0,28
0,010
0,29
0,30
3,55
0,07
0,07
0,07
0,001
0,075
0,076
1,33
0,07
0,07
0,06
0,0037
0,073
0,077
5,16
0,22
0,14
0,14
0,042
0,17
0,21
25,06
0,13
0,14
0,13
0,0056
0,13
0,14
4,13
0,61
0,61
0,60
0,0083
0,61
0,61
1,37
0,61
0,59
0,6
0,0097
0,60
0,61
1,61
0,25
0,28
0,24
0,017
0,26
0,27
6,87
0,24
0,26
0,24
0,0075
0,25
0,26
3,05
0,22
0,21
0,23
0,0075
0,22
0,23
3,41
0,22
0,22
0,21
0,0049
0,22
0,22
2,26
0,26
0,26
0,24
0,0098
0,25
0,26
3,85
0,23
0,23
0,21
0,013
0,22
0,23
6,04
0,22
0,22
0,22
0,0045
0,22
0,22
2,07
0,22
0,22
0,21
0,006
0,22
0,23
2,75
0,33
0,34
0,33
0,0083
0,33
0,34
2,47
0,35
0,37
0,33
0,0210
0,35
0,37
5,92
0,26
0,26
0,27
0,0047
0,26
0,27
1,75
0,26
0,24
0,24
0,010
0,25
0,26
4,16
0,34
0,39
0,039
0,37
0,41
10,55
0,34
0,36
0,35
0,0093
0,35
0,36
2,66
0,02
0,02
0,0007
0,023
0,024
3,0089
0,02
0,02
0,02
0,0005
0,02
0,021
2,84
0,24
0,24
0,24
0,0020
0,24
0,24
0,86
0,24
0,24
0,24
0,0017
0,24
0,24
0,7
0,04
0,04
0,04
0,0015
0,0416
0,043
3,66
0,04
0,03
0,03
0,0020
0,039
0,040
5,38
0,01
0,01
0,01
0,0017
0,012
0,0137
14,43
0,01
0,01
0,01
0,001
0,01
0,014
7,69
0,03
0,02
0,02
0,0015
0,029
0,030
5,20
0,01
0,01
0,01
0,001
0,01
0,019
5,55
0,01
0,01
0,01
0,003
0,014
0,017
24,74
0,01
0,01
0,01
0,003
0,01
0,018
19,92
0,02
0,01
0,01
0,0020
0,018
0,020
11,15
0,01
0,02
0,02
0,0026
0,02
0,02264
13,23
0,02
0,02
0,02
0,0011
0,027
0,028
4,22
0,02
0,02
0,02
0,001
0,02
0,024
4,34
0,07
0,07
0,06
0,0035
0,067
0,071
5,19
0,05
0,05
0,04
0,005
0,05
0,055
10
0,02
0,03
0,03
0,002
0,026
0,028
7,69
0,02
0,03
0,03
0,0036
0,03
0,03
13,35
0,04
0,04
0,04
0,0020
0,047
0,049
4,39
0,04
0,04
0,04
0,002
0,04
0,047
4,59
0,03
0,03
0,03
0,0015
0,031
0,033
4,87
0,03
0,03
0,03
0,0005
0,03
0,034
1,71
0,02
0,02
0,02
0,0020
0,023
0,025
8,79
0,02
0,01
0,02
0,0005
0,02
0,021
2,79
0,11
0,11
0,11
0,0043
0,112
0,12
3,89
0,11
0,10
0,11
0,001
0,11
0,111
0,91
0,61
0,66
0,7
0,062
0,674
0,73
9,24
0,65
0,69
0,70
0,029
0,68
0,71
4,31
18
VVRF05
Manuela Stierna Fernandez
International Water Summer Resources Research School 2015
Table 7 Concentration of total phosphorus present in the phosphorus samples
Concentration of total phosphorus present in the phosphorus samples (umol/L)
Using Potassium persulfate
Using Sodium persulfate
1104.5
1017.5
938.5
979
261
255
630.43
510.86
2206.43
2192.029
938.4
909.42
949.13
910.5
1142.39
1150.84
987.8
1021.01
719.06
719.14
727.08
727.08
1071.329
1123.909
871.92
816.36
1166.07
1109.02
Table 8 Concentration of total phosphorus present in the water samples
Water samples
Irrigation water
Spring lake
River water
Industry water
Coastal area water
Tap water
Concentration of TP using
Potassium persulfate
(μmol/L)
74.34
Concentration of TP using
Sodium persulfate
(μmol/L)
74.45
5.1
9.73
2.16
6.59
2.67
3.86
6.07
4.29
8.97
2.42
3.69
3.01
4.2
4.97
403.08
582.22
25.12
5
10.67
6.41
4.37
396.23
591.06
19.07
5.26
10.14
7.03
3.58
19