Sample Bag Update
Linda Coyne
SKC Inc.
Eighty Four, PA
Background
 The elimination of Tedlar served as a catalyst to
investigate other film materials
 Four films were evaluated in this study:
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SamplePro® FlexFilm (proprietary)
PVDF (also sold as Kynar®, Solef®, Hylar®)
FlexFoil® PLUS
FluoroFilm , FEP
In 2012, DuPont announced that it was bringing Tedlar
back to the bag market
Background/Applications
 Sampling bags have been used for many years to collect grab
samples
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Odor complaints in factories and refineries (VOCs, sulfurs)
Landfills (VOCs, CH4, CO2)
Preparation of calibration standards
Wastewater treatment plants (H2S, sulfurs)
Ventilation studies (mines, buildings)
Sources (industrial and stationary)
 Industrial are stacks, generally
 Stationary are hazardous waste incinerators and other combustions
sources
 Breath analysis
SamplePro FlexFilm
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3 mil proprietary film
236, 237 Series bags
Good storage stability for a wide variety of VOCs
High background of carbonyl sulfide and hydrogen
sulfide
 Similar permeability properties for water and CO2 as
Tedlar
 Economically priced
FlexFoil PLUS
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It is a 5 mil, 4 layer film
252, 253 series bags
PP/PE/Foil/PE
Special cleaning process which reduces the total VOC
background to approximately 20 ppb or less
Good moisture barrier properties
Ideal for any light sensitive compounds
Good stability for a wide range of VOCs
Good 48 hour stability for hydrogen sulfide
PVDF (Solef)
 It is a 2 mil PVDF film
 247, 248 series bags
 Similar permeability properties for water vapor and
CO2 to that of Tedlar
 It is also sold as Kynar and Hylar
 Fair VOC stability, compared to other films
 Low VOC and sulfur background
 Will make as specials until further notice
FluoroFilm FEP
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It is a 2 mil Tetrafluoroethylene copolymer
240, 243 series bags
Very low VOC and sulfur background
High permeability properties
Good VOC stability for Day 1 for many VOCs but
recoveries begin to fall off after 2 days
 Expensive film
Tedlar
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It is a 2 mil PVF film
231,232,233 series bags
Excellent stability for many VOCs
Durable film, rugged
High background of phenol and dimethyl acetamide
Methods for VOCs
 Tests were conducted with one liter bags, fitted with
polypropylene valve
 32 VOCs were tested by injecting know volumes of
the test analyte into the bag (individually)
 Bags were equilibrated for 20 to 30 minutes
 A 100 uL gas sample was injected from each bag into
a GC with FID; tests conducted on day 1 and day 2
 Concentrations ranged from 200-300 ppm, depending
on the analyte
Methods for Sulfur Compounds
 Tests were conducted with 1 liter bags, fitted with
polypropylene fittings
 Bags were tested at Eurofin Air Toxics Laboratory
 Bags were filled with a certified cylinder containing 20
sulfur gases at 90 ppb
 Analysis was conducted on Day 1 and Day 2
 Samples were analyzed using ASTM Standard Test
Method D-5504 using GC with Sulfur
Chemiluminescence Detection
Sulfur Compounds
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n-Butyl Mercaptan
T-Butyl Mercaptan
Carbon Disulfide
Carbonyl Sulfide
Diethyl disulfide
Diethyl sulfide
Dimethyl sulfide
2,5-Dimethylthiophene
Ethyl Mercaptan
Ethyl methyl sulfide
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2-Ethylthiophene
Hydrogen sulfide
Isobutyl mercaptan
Isopropyl mercaptan
Methyl mercaptan
3-Methylthiophene
N-Propyl mercaptan
Tetrahydrothiophene
Thiophene
Methods for Low Molecular Weight Gases
 Test compounds were carbon monoxide (CO), carbon
dioxide(CO2), methane(CH4), sulfur hexafluoride(SF6),
sulfur dioxide (SO2), and ammonia(NH3)
 Certified Scotty cylinders were used to fill each bag with
the test gas; all samples were analyzed on Day 0, Day 1 and
Day 2.
 CO, CO2, SO2, and NH3 were analyzed using Drager color
detector tubes
 CH4 and SF6 were analyzed by injecting 100 uL of the gas
sample from the bag into a GC with FID and ECD,
respectively.
Our Criteria of Acceptance
 Recovery is greater than or equal to 80% recovery
after 2 days of storage
Stability of VOCs in Four Bag Films
% Recovery
FlexFilm
PVDF
FlexFoil
PLUS
FEP
Tedlar
Compound
Day 1 Day 2
Day 1 Day 2
Day 1 Day 2
Day 1 Day 2
Day 1 Day 2
Acetone
96.7 88.9
81.6 69.8
99.0 97.8
89.0 85.0
99.0 95.0
Acetonitrile
69.0
55.1
55.0 36.3
94.2 84.5
65.0 42.0
74.0 66.0
CCl4
101
94.3
99.0 95.3
99.1 95.0
95.0 91.0
104 102
Ethyl
acetate
94.9 95.4
83.5 74.5
100 97.3
94.0 94.0
98.0 96.0
Hexane
99.0 98.9
97.3
101
95.8 99
98.0 95.0
101
IPA
99.1 91.7
97.4 90.5
101 100
102
101 99.0
Propylene
100 99.0
101 97.1
98.6 97.9
97.0 91.0
103
Benzene
96.0 95.2
84.0 78.0
93.1 98.2
93.0 79.0
104 98.0
Toluene
107 92.9
77.8 76.2
90.5 91.5
81.0 74.0
96.0 92.0
p-Xylene
85.9 82.7
69.0 49.0
97.0 89.0
76.0 65.0
89.0 83.0
98.0
101
104
Stability of Twenty Sulfur Compounds in Four Bag Films
% Recovery
FlexFilm
PVDF
FlexFoil
FEP
Day 1 Day 2
Day 1 Day 2
Day 1 Day 2
Day 1 Day 2
Hydrogen sulfide
7.8
2.2
73.1
46.2
104 102
72.2 47.8
Carbon disulfide
80.0
74.1
88.3
77.7
58.9 54.4
58.3 35.6
Carbony sulfide
126
135
93.3
80.0
98.9
82.9
Diethyl sulfide
68.2 54.1
53.3 36.7
11.1 12.2
62.9 49.5
Ethyl mercaptan
81.3 76.9
88.0 75.0
92.1 97.8
78.0 65.0
Methyl
mercaptan
78.9 67.8
87.0 73.9
93.4 102
74.0 57.0
Thiophene
81.6 75.9
80.7 64.8
61.1 62.2
76.0 64.0
Compound
108
71.2
Recommendations
 Analyze bags as soon as possible for sulfur
compounds
Stability of Low Molecular Weight Gases in Four Bag Films
% Recovery
FlexFilm
PVDF
FlexFoil
FEP
Tedlar
Compound
Day 1 Day 2
Day 1 Day 2
Day 1 Day 2
Day 1 Day 2
Day 1 Day 2
Ammonia
18.0 10.0
66.0 27.0
16.0 8.0
59.0 28.0
62.0 37.0
CO
100 100
100 90
100 100
90
50
90
90
CO2
100
100 100
99 100
90
50
100
100
99.0
90
CH4
96.0 92.0
100 101
99.0 100
84.0 72.0
101
SF6
104 99.8
96.8 92.0
98.1 93.2
96.4 92.8
94.7 93.2
SO2
80.0 67.0
67.0 53.0
0.0 0.00
33.0
80.0 67.0
0
Breath Analysis
 Disease recognition
 Therapy monitoring
 SKC offers the 239-01 and the 239-03 bags
Approximate Total VOC Background
Bag Film
Background (ppb)
FEP
10
FlexFoil PLUS
30
SamplePro FlexFilm
50
PVDF (Solef)
125
Tedlar
300
One liter bags were filled with air and set for 24 hours; the air was then
pulled from the bag onto a thermal desorption tube and analyzed by
FID/GC.
Sulfur Background (ppb)
Bag material
Carbonyl Sulfide
Carbon Disulfide
Hydrogen sulfide
SamplePro FlexFilm
68
ND (4ppb)
22
FlexFoil PLUS
13
ND (4ppb)
ND (4 ppb)
PVDF
10.0
ND (4 ppb)
ND (4 ppb)
FluoroFilm FEP
5.9
ND (4 ppb)
ND (4 ppb)
Tedlar
8.6
5.8
ND (4 ppb)
Conclusions
 Proper film choice really depends on the compound
to be sampled and time between sample collection
and analysis
 VOCs: Tedlar, FlexFilm and FlexFoil PLUS
 Sulfurs: Very compound dependent
 FEP: Low background but not great long term
stability
 All films good for SF6, CO, and CO2
You can find all of the bag stability data at
http://www.skcinc.com/instructions/1805.pdf