ASTM E2945-14(2021)

Standard Test Method for Film Permeability Determination Using Static Permeability Cells

SIGNIFICANCE AND USE
5.1 This test method provides a simple approach for determining the transmission properties of film membranes and sheeting over a range of permeability exceeding four orders of magnitude. This test method is described here to measure the permeability of films used in soil fumigation, but it is also appropriate for other gases and membranes if the analytical methods are appropriately modified.  
5.2 This test method can be used for single or mixed compounds. This test method uses small quantities of test chemicals in vapor form, and microgram to milligram quantities of each chemical may produce a sufficient amount of vapor for each test depending on the analytical methods.  
5.3 Interlaboratory testing showed that the MTC estimated by this test method is relatively insensitive to the laboratory procedures. The interlaboratory testing involved measuring the MTC for several soil fumigant compounds and a wide range of film permeability. Analysts with prior experience handling and analyzing gaseous fumigant compounds had lower coefficients of variation (10 % to 20 %) compared to less experienced analysts (20 % to 50 %) based on triplicate tests. The coefficient of variation between laboratories was higher for less permeable film materials than for films with high MTC. This was attributed to the additional length of the experiments and potential for increased leakage from the apparatus and was most pronounced for less experienced analysts.
SCOPE
1.1 This test method covers the measurement of the transmission of a gas through plastic membranes, sheeting, films, and fabric materials using a static sealed diffusion chamber. The test method monitors gas diffusion across a film membrane and provides measurements of (1) gas concentrations on each side of the film membrane and (2) estimates of the mass transfer coefficient (MTC) for the tested gas and film material. The MTC represents the film permeability and is independent of the concentration gradient used during testing, which simplifies some aspects of the experimental design.  
1.2 This test method permits the loading of mixed vapors and simultaneous determination of the permeability of one film to various gases.  
1.3 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Mar-2021
• ICS: 83.140.10 - Films and sheets
• Technical Committee: E35 - Pesticides, Antimicrobials, and Alternative Control Agents
• Drafting Committee: E35.22 - Pesticide Formulations and Delivery Systems

Relations

• Refers: ASTM D1898-68(1989) - Standard Practice for Sampling of Plastics (Withdrawn 1998)
• Effective Date: 29-Sep-2023
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM E691-11 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2011
• Refers: ASTM D618-08 - Standard Practice for Conditioning Plastics for Testing
• Effective Date: 01-Nov-2008
• Refers: ASTM E691-08 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Oct-2008
• Refers: ASTM D618-05 - Standard Practice for Conditioning Plastics for Testing
• Effective Date: 01-Nov-2005
• Refers: ASTM E691-05 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2005
• Refers: ASTM D618-00 - Standard Practice for Conditioning Plastics for Testing
• Effective Date: 10-Nov-2000
• Refers: ASTM E691-99 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 10-May-1999

Overview

ASTM E2945-14(2021) is the internationally recognized Standard Test Method for Film Permeability Determination Using Static Permeability Cells, developed by ASTM International. This standard provides a reliable, straightforward approach for evaluating the transmission properties of film membranes, sheeting, and similar flexible materials. Using a static sealed diffusion chamber, the standard method quantifies the permeability of gases-such as those used in soil fumigation films-but can also be adapted for other membranes and gases with appropriate modifications to analytical methods.

The test method involves measuring gas diffusion across a film and determining the mass transfer coefficient (MTC), which reflects the film's permeability and is not influenced by the concentration gradient. This simplifies experimental design and supports comprehensive comparisons across a wide range of film materials and gas types.

Key Topics

• Film Permeability Measurement: The standard describes a procedure using static permeability cells to assess the mass transfer of gases through plastic films, membranes, sheeting, and fabrics.
• Mass Transfer Coefficient (MTC): Central to the method, the MTC offers a quantifiable metric for gas permeability, allowing for comparisons between different film types and testing conditions.
• Testing Process: Gas samples are introduced and monitored on both sides of the test film within a sealed chamber. Gas concentration data is collected at various intervals, up to equilibrium, facilitating both rapid and extended timelines depending on the film's permeability.
• Applicability for Multiple Gases: The method supports simultaneous testing with single or mixed gases, making it versatile for both pure and complex vapor mixtures.
• Quality and Reproducibility: Interlaboratory studies cited in the standard show that MTC measurement is generally stable and reproducible. Experienced analysts tend to yield lower variability, particularly for films with low permeability.

Applications

• Agricultural Films and Fumigation: Originally tailored to evaluate films used in soil fumigation (e.g., controlling gas transmission of methyl bromide or other soil fumigants), the method is directly applicable to agricultural plastic sheeting, mulches, and vapor barriers.
• Packaging and Industrial Films: The standard is also suitable for evaluating packaging films, industrial membrane applications, and any film used for gas barrier performance.
• Material Development and Quality Control: Manufacturers and researchers use ASTM E2945-14(2021) to benchmark new membrane materials, optimize product formulations, and ensure compliance with regulatory requirements for permeability.
• Environment and Safety Assessments: By quantifying the transmission rates of potentially hazardous vapors, the method assists in risk assessment and environmental impact studies.

Related Standards

• ASTM D618: Standard Practice for Conditioning Plastics for Testing - details preconditioning and handling that support accurate permeability measurement.
• ASTM E691: Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method - provides methodologies referenced for ensuring reproducibility.
• ISO 15105: Permeability measurement of plastic films and sheeting - Shares a similar scope for gas transmission but may use different methodologies.
• Other ASTM Film Testing Standards: ASTM offers several complementary methods related to polymer film properties and vapor permeation not specific to static permeability cells.

By following ASTM E2945-14(2021), organizations gain a precise, standardized means to determine and compare the gas permeability of various films, ensuring better product performance, regulatory compliance, and material certification across industrial, agricultural, and environmental contexts.

For more information or to purchase the standard, visit ASTM International.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E2945 − 14 (Reapproved 2021)
Standard Test Method for
Film Permeability Determination Using Static Permeability
Cells
This standard is issued under the fixed designation E2945; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D1898Practice for Sampling of Plastics (Withdrawn 1998)
E691Practice for Conducting an Interlaboratory Study to
1.1 This test method covers the measurement of the trans-
Determine the Precision of a Test Method
mission of a gas through plastic membranes, sheeting, films,
and fabric materials using a static sealed diffusion chamber.
3. Terminology
Thetestmethodmonitorsgasdiffusionacrossafilmmembrane
3.1 Definitions:
and provides measurements of (1) gas concentrations on each
3.1.1 concentration, C, n—chemical mass divided by the
side of the film membrane and (2) estimates of the mass
chamber volume.
transfer coefficient (MTC) for the tested gas and film material.
3.1.1.1 Discussion—C is the initial (t = 0) concentration in
The MTC represents the film permeability and is independent
o
the source chamber. The SI unit of concentration is µg/cm .
of the concentration gradient used during testing, which
simplifies some aspects of the experimental design.
3.1.2 concentration gradient, n—difference in the concen-
tration of gases across the film membrane divided by the
1.2 This test method permits the loading of mixed vapors
transport distance between the source and collection chambers
andsimultaneousdeterminationofthepermeabilityofonefilm
(for example, usually considered to be the film thickness).
to various gases.
3.1.2.1 Discussion—The SI unit of the concentration gradi-
1.3 Units—The values stated in SI units are to be regarded
ent is µg/cm -cm.
as the standard. No other units of measurement are included in
3.1.3 mass transfer coeffıcient, MTC, n—gas diffusion rate
this standard.
constant that relates the mass transfer rate, distance, and
1.4 This standard does not purport to address all of the
concentration gradient as the driving force through a film
safety concerns, if any, associated with its use. It is the
membrane under the test conditions.
responsibility of the user of this standard to establish appro-
3.1.3.1 Discussion—TheSIunitoftheMTCiscm/hour.The
priate safety, health, and environmental practices and deter-
MTC expresses the ease of transmission of a gas through a
mine the applicability of regulatory limitations prior to use.
membrane under test conditions. The test conditions shall be
1.5 This international standard was developed in accor-
stated, which include the ambient temperature, relative
dance with internationally recognized principles on standard-
humidity, film conditioning, sampling, and handling.
ization established in the Decision on Principles for the
3.1.4 mass transfer rate, J, n—mass transfer rate, or flux
Development of International Standards, Guides and Recom-
density,ofagasdiffusingthroughafilmmembraneisthemass
mendations issued by the World Trade Organization Technical
of gas passing through a unit area (for example, 1 cm)offilm
Barriers to Trade (TBT) Committee.
membraneperunittimeinterval(forexample,1h).TheSIunit
2. Referenced Documents
of J is µg/cm hour.
2.1 ASTM Standards:
4. Summary of Test Method
D618Practice for Conditioning Plastics for Testing
4.1 This test method uses a static sealed apparatus consist-
This test method is under the jurisdiction of ASTM Committee E35 on
ing of two chambers separated by the test-film membrane.The
Pesticides, Antimicrobials, and Alternative Control Agents and is the direct
testchemicalinthevaporphaseisaddedtothechamberonone
responsibility of Subcommittee E35.22 on Pesticide Formulations and Delivery
side of the film and the apparatus is incubated at constant
Systems.
Current edition approved April 1, 2021. Published April 2021. Originally temperature during which the chemical diffuses through the
approved in 2014. Last previous edition approved in 2014 as E2945–14 DOI:
test membrane. This test method requires determination of the
10.1520/E2945-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2945 − 14 (2021)
FIG. 1 Schematic of Static Film Permeability Apparatus Consisting of Two Parts: A Source and Collection Chamber with a Film Mem-
brane between Them
relative chemical concentrations on both sides of the mem- cient of variation between laboratories was higher for less
brane at several time points during the incubation. Concentra- permeable film materials than for films with high MTC. This
tions are monitored until equilibrium is reached or some other
was attributed to the additional length of the experiments and
practical stoppage time. For permeable films, more frequent potential for increased leakage from the apparatus and was
sampling is necessary because equilibrium may be reached
most pronounced for less experienced analysts.
within minutes or hours. For films with very low permeability,
longer incubation times (weeks) may be necessary to reach
6. Apparatus
equilibrium.Linearregressionofdatamaybeusedtocalculate
6.1 Asealed apparatus is constructed of inert and imperme-
the mass transfer coefficient (MTC). Alternatively, an analyti-
able material (for example, stainless steel) such that a sample
cal solution to a mathematical model may be used to calculate
oftestmembraneisheldbetweenthetwochambersinaclosed
MTC (see Appendix X1) for which a nonlinear least-square
system. The selection of material is dependent on the gases
algorithm is available to fit concentrations derived from the
being considered. The apparatus (see Fig. 1) enables sampling
mathematical model to the observed concentrations. See Pa-
4,5
of the time rate of change in the gas concentration in each
piernik et al for additional details.
chamber and the mass transfer coefficient. The apparatus is
5. Significance and Use
configured as shown in Fig. 1.
5.1 This test method provides a simple approach for deter- 6.1.1 Permeability Apparatus—Stainless steel pipe (for
mining the transmission properties of film membranes and
example, 0.3cm to 0.6cm thick, 10cm to 15cm diameter) is
sheeting over a range of permeability exceeding four orders of cut to form cylinders with height 2cm to 6cm.The volume of
magnitude. This test method is described here to measure the
the chamber affects the time to reach equilibrium; therefore,
permeability of films used in soil fumigation, but it is also
taller cylinders are appropriate for testing permeable films,
appropriate for other gases and membranes if the analytical
shortercylindersforlesspermeablefilms.Theendsofthepipe
methods are appropriately modified.
are trued and the mating surfaces smoothed. Each cylinder is
welded to a flat steel plate (for example, 0.3 cm thick) at one
5.2 This test method can be used for single or mixed
end, as shown in Fig. 2.
compounds. This test method uses small quantities of test
chemicals in vapor form, and microgram to milligram quanti-
6.1.2 Sampling Ports—Holesaredrilledandthreadedonthe
tiesofeachchemicalmayproduceasufficientamountofvapor
side of each cylinder to allow installation of sampling ports.
for each test depending on the analytical methods.
The holes should be located near the mid-point height of the
cylinder (Figs. 1 and 2).
5.3 Interlaboratory testing showed that the MTC estimated
by this test method is relatively insensitive to the laboratory 6.1.3 The purpose of the ports is to allow access to the
procedures.Theinterlaboratorytestinginvolvedmeasuringthe inside of the chamber for spiking and sampling. During other
MTCforseveralsoilfumigantcompoundsandawiderangeof times, ports should be sealed to prevent leakage. This can be
film permeability.Analysts with prior experience handling and accomplished using a septum port or sampling valve as
analyzing gaseous fumigant compounds had lower coefficients
described in 6.1.3.1 and 6.1.3.2.
of variation (10% to 20%) compared to less experienced
6.1.3.1 Septum Port—A 1.6mm steel (or brass) union con-
analysts (20% to 50%) based on triplicate tests. The coeffi-
nector is installed in each hole. Before installation, the threads
of the union are coated with epoxy to ensure a gastight seal.
One port is installed in the collection chamber and two ports
Papiernik, S. K., Yates, S. R., and Gan, J., “An approach for estimating the
permeability of agricultural films,” Environmental Science and Technology, Vol 35,
(on opposite sides of the cylinder) are installed in the source
2001, pp. 1240-1246.
chamber. The second port is used to vent the source chamber
Papiernik, S. K., Ernst, F. F., andYates, S. R., “An apparatus for measuring the
during spiking. A septum and threaded nut are installed onto
gas permeability of films,” Journal of Environmental Quality, Vol 31, 2002, pp.
358-361. the1.6mmunionandtheunionthreadscoatedwithepoxy.The
E2945 − 14 (2021)
FIG. 2 Top View of the Source Chamber—A Stainless Steel Cylinder Is Welded to the Stainless Steel Bottom Plate Leaving One End of
the Cylinder Open
threadednutiscoveredbyaSwagelok capandaseptum(Fig. 7.4 A constant-temperature environmental chamber is used
3A). Samples are collected with a syringe by removing the to maintain constant temperature during testing. Since the
outer septum and cap and piercing through the septum behind temperature is known to affect the MTC value, the variation in
the threaded nut (Fig. 3A). Between sampling, the nonpunc- the temperature set point should be no more than 62°C.
turedseptumandcapshouldbetightenedoverthethreadednut
7.5 Miscellaneous—An assortment of gastight syringes (for
to prevent leakage from the pierced septum between sampling
example,10µLto100mLcapacity),Tedlarbagwithsampling
times.
port (for example, 0.6L capacity), gas chromatograph au-
6.1.3.2 Sampling Valve Port—A gastight sampling valve is
tosampler vials, caps that are inert to the test gas, crimpers,
screwed onto the union (Fig. Fig. 3A) or directly into the
timers, epoxy glue, aluminum adhesive tape.
chamberwallandthethreadssealedwithepoxy(Fig.Fig.3B).
7.6 Gas Chromatograph/Mass Spectrometer Equipped with
One valve is installed in the collection chamber and one valve
Appropriate Capillary Column—A gas chromatograph (GC)
is installed in the source chamber. The valve shall be made of
with electron capture detector (ECD) can also be used for
inertandimpermeablematerialandproduceagastightconnec-
analysis of halogenated fumigants, such as methyl bromide,
tion to the cylinder wall. A polytetrafluoroethylene stopcock
iodomethane, chloropicrin, 1,3-dichloropropene, and sulfuryl
screwedontotheunionallowssampleintroductionorremoval.
fluoride. Equipment that includes an autosampler provides
Astainlesssteeltwo-wayvalve(1.6mm)screweddirectlyinto
added convenience.
thedrilledholecouldalsobeusedtoallowsampleintroduction
or removal (Fig Fig. 3B). The air volume within the valve 7.7 Other Gases, appropriate sampling and detection equip-
should be minimized.
ment as needed.
NOTE 1—Other configurations for the chamber access ports are
8. Potential Hazards
possible, but design criteria and testing should demonstrate that they: (1)
8.1 General—Appropriate laboratory and chemical safety
are constructed of inert materials, (2) are non-leaking between sampling
times, (3) minimize leaking during sampling, and (4) maintain integrity
procedures should be followed and materials and gases should
during routine laboratory handling.
be used in accordance with information provided on product
labels, safety data sheets, and established laboratory safety
7. Materials
guidelines.
7.1 The apparatus can be used to measure diffusion of an
8.2 Gases under Pressure—When using gases stored under
arbitrary gas through a film membrane. The specifics of the
high pressure, the dispensing equipment should be appropriate
methodology described in the following relate to fumigant
fortheintendeduse.Theequipmentshouldberatedforthegas
gases and fumigation films, but the test method can be
cylinder or gas-line pressures, or both, and pressure-reducing
modifiedtoallowmeasuringtheMTCforothergasesandother
valves and regulators used where needed.
membranes.
8.3 Fumigation gases are a class of chemicals that pose
7.2 Fumigant Chemicals—Iodomethane, 1,3-
significant health hazards. They generally are irritants and
dichloropropene (mixture of cis and trans isomers), dimethyl
toxic. Adverse human health effects include harm if inhaled,
disulfide, methyl isothiocyanate (transformation product of
swallowed, or absorbed through the skin; appropriate safety
metam sodium or dazomet during fumigation), chloropicrin,
procedures should be used.
methyl bromide, and sulfuryl fluoride.
9. Sampling, Test Specimens, and Test Units
7.3 Gas-Mixing Chamber—Gastight 1L glass container
withvalvesonbothendsandasidesamplingport.Othertypes
9.1 Test specimens should be sampled in accordance with
of gastight containers with sampling ports may be used. If a PracticeD1898.Testedsamplesshouldberepresentativeofthe
clear glass container is used, it is recommended that the glass
bulk material; free of wrinkles, stretches, pinholes, other
container be wrapped with aluminum foil to protect the imperfections;andofuniformthickness.Surfaceconditionand
fumigants from light. Some fumigants are photodegradable.
differences in materials or construction of each side of the film
shall be reported.
9.2 Cutthefilmtestspecimensintoapproximately15cmby
Swagelok is a registered trademark of the Swagelok Company, Cleveland,
Ohio. 15cm pieces.
E2945 − 14 (2021)
3A Sampling Port Design
3b Sampling Port Design
FIG. 3 Sampling Port Design
9.3 Information concerning the film composition (for 10.3 Replication—In general, triplicate permeability appa-
example, thickness, presence of ultraviolet [UV] stabilizers, ratuses are constructed for each test film and the MTC is
barrier polymers and additives, and so forth) and manufactur- calculated for each replicate. The average and standard devia-
ing should be reported, when available. tion of the triplicates should be reported.
11. Calibration and Standardization
10. Preparation of Apparatus
11.1 Quantitation—Determineinstrumentresponseforeach
10.1 Mix together a small amount of the epoxy resin and
fumigant by injecting fumigant mixtures at varying concentra-
hardener. Spread a thin layer of the well-mixed epoxy glue
tions into the instrument and creating a calibration curve.
over the exposed rim of the open edge of the source chamber
Using the same procedure as in 13.3.1, transfer aliquots (for
side of the permeability apparatus using a flat stainless steel
example, 5µL, 10µL, 20µL, 50µL, 100µL, and 500µL) of
spatula. Place the test film onto the edge containing the glue.
the test vapor from the 1L mixing chamber (13.1) into vials.
Make sure the film is spread flat and evenly (not stretched and
The fumigant concentrations in the vials are estimated using
withnocrevices).Spreadathinlayerofwell-mixedepoxyglue
the values from 13.1.1.4 (Table 1 as an example) and the
over the exposed rim of the collection chamber of the perme-
volume of the standard mixture placed in the vial.
abilityapparatus.Carefullyplacetherimofcollectionchamber
11.1.1 This method of preparing standards is suggested
over the film and mate the two halves of apparatus by aligning
becauseabsoluteconcentrationsarenotrequiredforthesetests.
and joining them together to form a gastight seal. Care should
Other methods of constructing calibration curves that result in
be taken to place the film and mate the two chambers with
more exact determination of chemical concentration are ac-
minimal movement after contact.
ceptable so long as they conform to the standards of analytical
10.2 After the glue is cured (usually overnight), trim the
chemistry.
excess film with a razor blade. Apply aluminum tape to the
11.2 Theconcentrationoffumigantineachchamberofeach
outside of the apparatus over the seam between chambers and
apparatus during a test is determined by comparing the
burnish to provide additional support and sealing of the
instrument response for each sample against the instrument
apparatus. Place the constructed apparatus inside a
calibration curve.
temperature-controlled environment set at the target tempera-
ture and equilibrate for a minimum of 60 min before introduc-
11.3 Alternative Measurements—The methodology used to
ing the fumigants.
calculate the MTC uses the ratio C/C in the source and
o
NOTE 2—The time needed to reach temperature equilibrium is depen-
collection chambers.Alternative ratios, for example, peak area
dent on the materials and quantities used for the apparatus.Apreliminary
divided by peak area in source chamber at the start of the test,
study should be conducted to determine the equilibrium time for a
can also be used if the instrument response is linear and
particular test apparatus, and the measured equilibrium time should be
used during testing. provides identical results.
E2945 − 14 (2021)
TABLE 1 Estimated Concentrations of Fumigants Present in the 1-L Mixing Chamber Based on the Suggested Procedures in 13.1.1.1 –
13.1.1.3
Gas or Amount of Calculated Concentration
Fumigant State Liquid Density Pure Material in Mixing Chamber
(mg/mL) Added to Mixing Chamber (µg/mL of air)
Sulfuryl fluoride gas 4.24 30 mL of gas (from Tedlar bag) 127 µg/mL
Methyl bromide gas 3.97 30 mL of gas (from Tedlar bag) 119 µg/mL
A A
1,3-dichloropropylene gas 1.22 40 µL 24.4 µg/mL
Iodomethane liquid 2.28 20 µL 45.6 µg/mL
Chloropicrin liquid 1.69 20 µL 33.8 µg/mL
Dimethyl disulfide liquid 1.06 20 µL 21.2 µg/mL
Methyl isothiocyanate solid – 20 mg 20 µg/mL
A
1,3-dichloropropene has two isomers (cis, trans) in an approximately 50:50 mixture. The calculated concentration of each isomer in the mixing chamber is 24.4 µg/mL.
Tedlar bag and degrade over time and, therefore, cannot be stored in a
12. Conditioning
Tedlar bag for long periods.Also, some fumigants, such as methyl iodide,
12.1 Standard Conditioning—In accordance with Practice
chloropicrin, 1,3-dichloropropene, and methyl isothiocyanate are photo-
D618 Procedure A for films with thickness less than 7 mm, sensitive and degrade quickly when exposed to light. Exposure of the
containers containing fumigants to light should be minimized.
condition all test specimens in a laboratory at standard condi-
tions(thatis,23°C 62°Cand50% 65%relativehumidity)
13.1.1.4 The estimated concentration of each fumigant,
for 40h or more before attaching the film membrane to the
expressedasµg/mL,inthe1Lglasschambercanbeestimated
permeability apparatus and sealing with aluminum tape.
based on the assumption that the entire amount of each
fumigant has completely evaporated in the chamber and the
12.2 Other Temperatures—When tests are required at other
resultant gases are well mixed. Assuming complete
temperatures, the film should be conditioned at the test
vaporization, the estimated concentration of each fumigant in
temperature.
the vapor phase of the mixing chamber is calculated based on
12.3 Other Relative Humidity—When tests are required at
the amount added (for example, mass) of each compound
nonstandard relative humidity, the film and constructed appa-
divided by the chamber volume (1L). Since complete vapor-
ratus should be conditioned at the test relative humidity in
ization and mixing within the chamber cannot be verified, the
accordance with Practice D618. The conditioning and relative
calculated chamber concentrations should be considered esti-
humidity of the collection and source chambers shall be
mates. Table 1 summarizes the approximate concentrations for
reported.
the stated amounts using 13.1.1.1 – 13.1.1.3.
12.4 In-Situ Conditioning—Prepare apparatus as in Section
13.1.1.5 The amount of each fumigant transferred to the
10 and then sweep air at standard conditions through the
mixing chamber and the subsequent transferring of gas to the
assembledapparatusfor40minormorebeforeinitiatingatest.
apparatus can vary, as long as a sufficient quantity of gas is
present in the apparatus for instrumental analysis. Therefore,
13. Procedure
an excessive quantity may be transferred to the mixing
13.1 Preparation of Test Vapor: chamber to provide a saturated vapor. After establishing the
13.1.1 Fumigant Mixture Preparation: linear range of the analytical instrument, quantitative transfer-
13.1.1.1 Solids—Transfer a small amount of solid fumigant ring of a given quantity of fumigant vapor to the apparatus is
(for example, methyl isothiocyanate) (about 20 mg to 50 mg) not required because the use of concentration ratios, that is,
into the 1-L glass chamber. C/C or equivalent, is sufficient.
o
13.1.1.2 Liquids—Transfer about 20 µL to 50 µL of each 13.1.2 Mixture Preparation for Other Gases—The proce-
liquid fumigant standard into the 1L glass mixing chamber durein13.1.1canbemodifiedtoenableestimationoftheMTC
using a pipette or syringe. for gases other than fumigants.
13.1.1.3 Gases—In a fume hood, transfer a small amount
13.2 Adding Test Gas to Apparatus—Temporarily move the
(about 100mL to 500mL volume) of each gas (for example,
apparatusfromthetemperaturechambertoafumehood.Close
methyl bromide and sulfuryl fluoride) from a compressed gas
thecollectionchamberport,openthesourcechamberport,and
cylinder into a Tedlar bag, for example, using a small piece of
then withdraw approximately 30mL to 40mL volume of the
copper tubing, a step-down regulator, and a short piece of
vapor from the 1L mixing chamber using a gastight syringe.
flexible tubing attached to a syringe needle. Using a gastight
Inject the vapor into the source chamber (typically the bottom
syringe, transfer about 30mL of the collected gaseous com-
chamber) of the permeability apparatus and immediately close
pounds from the Tedlar bag to the 1L mixing chamber.
all valves/ports. Start timer to track incubation time. Return
apparatus to the temperature chamber for incubation.
NOTE 3—The fumigants should be left in the mixing chamber for a
minimum of 30 min to allow equilibration of the concentration inside the NOTE 4—If the apparatus includes a septum/cap (6.1.3.1), the venting
mixingchamberbeforeuse.Themixingchambermaybeplacedinawarm valve should be opened before injection to avoid pressurizing the
place (for example, up to 40°C oven) to facilitate the vaporization of the chambers.This can be accomplished by inserting a small-diameter needle
fumigants. Methyl bromide and sulfuryl fluoride diffuse through the through the inside septum of the venting port. If an on/off valve is used
E2945 − 14 (2021)
(6.1.3.2), the excess air/vapor will escape around the needle and no TABLE 2 Ions Monitored in the GC/MS Analysis
ventingvalveisneeded. Theamountofthevaporinjectedintothesource
Retention Primary Secondary
Fumigant
chamber of the permeability apparatus may be adjusted to obtain a
Time (min) Ion (m/z) Ions (m/z)
sufficientamountofcompound(s)tobeanalyzeddependingoninstrument
Sulfuryl fluoride 1.5 102 83, 67
sensitivity.
Methyl bromide 2.3 94 96, 79
Methyl iodide 3.6 142 127, 141
13.3 Sampling Gas from Apparatus:
cis-1,3-dichloropropene 14.2 75 39, 110
13.3.1 At the appropriate sampling interval, use gastight
Dimethyl disulfide 14.3 94 79, 45
syringes to withdraw equal and fixed volume of gas samples Methyl isothiocyanate 16.0 73 45, 72
Chloropicrin 16.6 117 119, 82
(for example, 250µL) from both the collection and source
trans-1,3- dichloropropene 16.7 75 39, 110
chambers of each permeability apparatus. Note the exact
sampling time for each replication. Follow one of the extrac-
tion procedures in 13.3.1.1 or 13.3.1.2 depending on the
method of instrumental analysis. of the MTC. The purpose of frequent sampling is to obtain
sufficient data points to calculate MTC reliably, particularly at
NOTE 5—Dedicated syringes should be used for sampling the source
thebeginningoftheexperimentwhenchangesinconcentration
andcollectionchambersasagoodlaboratorypractice.Dedicatedsyringes
are the largest.
are essential for pesticides (for example, chloropicrin) that tend to adhere
to the glass inside of the syringe. Using the same syringe to sample both
13.3.6 Testing Completion—Movetheapparatustothefume
chambers could lead to contamination of the low-concentration sample if
hood and open the ports to allow test chemicals to escape.
the high-concentration sample (for example, source chamber) is collected
Disassembletheapparatusandremovetheepoxygluefromthe
first or if the syringe is not completely cleaned between sample collection
edges of the cylinders. Replace septa if apparatus used septum
times (see 13.3.3).
ports.
13.3.1.1 Extraction Procedure A—With the vial cap held
NOTE7—.Foranapparatusthatisdifficulttodisassembleduetoepoxy
askew on top of the vial, inject gas sample into the bottom of
bond strength, using a rubber mallet, or equivalent, and tapping one half
a 10-mL headspace autosampler vial. Close the vial immedi-
oftheapparatusmayhelptoloosenthebond.Heatingepoxyalsoweakens
atelyusingaluminumcrimpcapswithpolytetrafluoroethylene-
bond strength.Arazor blade maybe used to remove the epoxy glue from
faced butyl rubber septa.
the metal surfaces.
13.3.1.2 Extraction Procedure B—Injectgassampleintothe
13.4 Sample Analysis:
bottom of a GC vial or 10mL headspace vial filled with
13.4.1 Analysis Equipment—For fumigants and similar or-
approximately 2mL of solvent. Close the vials immediately
ganic chemicals, gas samples are analyzed using a gas
using aluminum crimp caps with polytetrafluoroethylene
chromatograph/mass spectrometer (GC/MSD) with a head-
-faced butyl rubber septa.
space(ifusing13.3.1.1)orliquidautosampl
...