ASTM F2013-10(2016)

Standard Test Method for Determination of Residual Acetaldehyde in Polyethylene Terephthalate Bottle Polymer Using an Automated Static Head-Space Sampling Device and a Capillary GC with a Flame Ionization Detector

SIGNIFICANCE AND USE
5.1 This test method is of particular use as a quality control tool for a molding or synthesis operation. Acetaldehyde is a volatile degradation product generated during melt processing of PET. Thus, it becomes trapped in the sidewalls of a molded article and desorbs slowly into the contents packaged therein. In some foods and beverages AA can impart an off-taste that is undesirable, thus, it is important to know its concentration in PET articles that are to be used in food contact applications.  
5.2 The desorption conditions of 150 C for 60 min are such that no measurable AA is generated by the sample during the desorption process.
SCOPE
1.1 This test method covers a gas chromatographic procedure for the determination of the ppm residual acetaldehyde (AA) present in poly(ethylene terephthalate) (PET) homo-polymers and co-polymers which are used in the manufacture of beverage bottles. This includes sample types of both amorphous and solid-stated pellet and preform samples, as opposed to the bottle test, Test Method D4509, an acetaldehyde test requiring 24 h of desorption time at 23°C into the bottle headspace and then the concentration of the headspace quantified by a similar GC method.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 30-Apr-2016
• ICS: 55.100 - Bottles. Pots. Jars
• Technical Committee: F02 - Primary Barrier Packaging
• Drafting Committee: F02.15 - Chemical/Safety Properties

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: F2013 − 10 (Reapproved 2016)
Standard Test Method for
Determination of Residual Acetaldehyde in Polyethylene
Terephthalate Bottle Polymer Using an Automated Static
Head-Space Sampling Device and a Capillary GC with a
Flame Ionization Detector
This standard is issued under the fixed designation F2013; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This test method covers a gas chromatographic proce- 3.1 The terms employed in this test method are commonly
dure for the determination of the ppm residual acetaldehyde used in normal laboratory practice and require no special
(AA) present in poly(ethylene terephthalate) (PET) homo- comment.
polymers and co-polymers which are used in the manufacture
4. Summary of Test Method
of beverage bottles. This includes sample types of both
4.1 A specified size (< 1000 µm) of granulated sample is
amorphous and solid-stated pellet and preform samples, as
weighed into a 20-mL head-space vial, sealed, and then heated
opposed to the bottle test, Test Method D4509, an acetaldehyde
at 150°C for 60 min. After heating, the gas above the sealed
test requiring 24 h of desorption time at 23°C into the bottle
sample of PET polymer is injected onto a capillary GC column.
headspace and then the concentration of the headspace quan-
The acetaldehyde is separated, and the ppm of acetaldehyde is
tified by a similar GC method.
calculated.
1.2 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this 5. Significance and Use
standard.
5.1 This test method is of particular use as a quality control
1.3 This standard does not purport to address all of the
tool for a molding or synthesis operation. Acetaldehyde is a
safety concerns, if any, associated with its use. It is the volatile degradation product generated during melt processing
responsibility of the user of this standard to establish appro-
of PET. Thus, it becomes trapped in the sidewalls of a molded
priate safety and health practices and determine the applica-
article and desorbs slowly into the contents packaged therein.
bility of regulatory limitations prior to use.
In some foods and beverages AA can impart an off-taste that is
undesirable, thus, it is important to know its concentration in
2. Referenced Documents
PET articles that are to be used in food contact applications.
2.1 ASTM Standards:
5.2 The desorption conditions of 150 C for 60 min are such
D4509 Test Methods for Determining the 24-Hour Gas that no measurable AA is generated by the sample during the
(AIR) Space Acetaldehyde Content of Freshly Blown PET
desorption process.
Bottles (Withdrawn 2004)
6. Sources of Error
E691 Practice for Conducting an Interlaboratory Study to
6.1 A bias is known to exist if the ratio of sample mass (mg)
Determine the Precision of a Test Method
to head-space vial volume (mL) exceeds a value of ten.
6.2 Acetaldehyde is very volatile and must be handled
This test method is under the jurisdiction of ASTM Committee F02 on Flexible carefully to avoid sample loss during the calibration procedure.
Barrier Packaging and is the direct responsibility of Subcommittee F02.15 on
Storing the standard vials in a refrigerator (4 6 2°C) is a must
Chemical/Safety Properties.
to minimize the error due to volatility.
Current edition approved May 1, 2016. Published June 2016. Originally
approved in 2000. Last previous edition published in 2010 as F2013 – 10. DOI:
6.3 Failure to achieve a tight seal on the head-space vial will
10.1520/F2013-10R16.
result in the loss of acetaldehyde during storage and
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
desorption, producing a false low value.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
6.4 Failure to grind the sample to the appropriate particle
the ASTM website.
3 size may lead to a false low value for residual AA due to the
The last approved version of this historical standard is referenced on
www.astm.org. increased path length for desorption.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2013 − 10 (2016)
6.5 Samples submitted for “residual AA measurement” 9.2 Using the syringe, fill it by placing the tip in the liquid
should be stored in a freezer (< –10°C) until they are tested. standard and quickly moving the plunger up and down several
Failure to do so can result in lower than expected results. time to evacuate any bubbles, then pull the plunger back past
the 2.000-µL mark to 2.200 to 2.250 µL.
6.6 Excessive grinding of samples can cause residual AA
contained therein to be desorbed. Extensive excessive grinding 9.3 Wipe the syringe needle with a tissue.
can lead to actual melting of the polymer and AA generation.
9.4 Depress the plunger until the digital readout is 2.000 µL.
Samples which have been chilled in liquid nitrogen properly
9.5 Smear the excess liquid that is on the syringe tip on the
should only be in the grinder for ;30 s or less.
OUTSIDE of the headspace vial.
7. Apparatus 9.6 Place the syringe inside of the vial so that the tip just
touches the bottom of the vial.
7.1 Gas Chromatograph, equipped with a flame ionization
detector. 9.7 Quickly inject the liquid standard into the vial and swirl
the syringe tip around the inside of the vial to smear all liquid
7.2 Integrator or a PC with data acquisition software.
on the vial walls.
7.3 Head-Space Sampler—(a static head-space sampler).
9.8 Remove the syringe and IMMEDIATELY cap the vial.
7.4 Column, 30-m by 0.53-mm inside diameter (DVB po-
9.9 Calculate the weight of AA based on the standard’s
rous megabore capillary column or equivalent).
certified value and a 2.000-µL injection volume.
7.5 Vials, 20-mL, head-space, with 20-mm septa, 20-mm
NOTE 2—Acetaldehyde is very volatile. The AA ampules must be stored
aluminum caps, and crimper for 20-mm caps.
in a refrigerator, and the standards prepared immediately after breaking
open an ampule.
7.6 Crimper, 20-mm.
9.10 Analyze the working standard by the procedure de-
7.7 Decrimper, 20-mm.
scribed in Section 11, starting with 11.2.11.
7.8 Wiley Mill, equipped with an 800 to 1000-µm screen, or
9.11 Calculate an AA response factor for the standard using
equivalent.
the following equation:
7.9 Syringe, (gas tight) calibrated, with certificate of cali-
response factor of AA5 Wt of AA in μg/area of AA (1)
bration.
NOTE 3—Due to the error associated with the certified standard, 9.1 –
7.10 Small Vacuum Cleaner, with hose attachment for clean- 9.11 should be performed five times using five different standard ampules.
ing.
9.12 Average the five response factors obtained, and use this
value for the sample analyses.
7.11 Analytical Balance, capable of accurately weighing to
at least 60.0001 g.
9.13 Manually enter the calculated response factor in the
calibration list of the integrator or data system.
7.12 Hammer.
NOTE 4—During a series of sample analyses, a periodic check of
7.13 Air for EID.
instrument performance is recommended by placing a few liquid standard
7.14 Helium 99.9995 % purity as carrier gas.
samples throughout the sample set. If these values fall out of the
acceptable range as specified by the certificate of analysis, recalibration
7.15 Hydrogen 99.9995 % purity for flame ionization detec-
(9.1 – 9.12) should be performed.
tor (FID) or can be used as carrier gas.
10. Sample Preparation
7.16 Spatular.
10.1 Parisons or Preforms or Plaques—May be cryogeni-
7.17 Dewer flask.
cally ground whole, or can be broken into small pieces with a
7.18 Glass jar or manila envelope.
hammer (using liquid nitrogen) and then ground with the aid of
grinding mill equipped with a 20-mesh or <1000-µm screen.
7.19 Wipe paper or tissue.
The grind should be thoroughly homogenized before sampling
7.20 Digital syringe, equipped with a 10-L glass syringe.
for AA. If the appropriate size screen is not available on the
large grinding mill, then it is suggested that the sample be
8. Reagents and Materials
ground to 3 to 6 mm on the large mill and the sample
8.1 Acetaldehyde (AA), 500 ppm AA in water (or 1000 thoroughly homogenized. A portion can then be taken to a
ppm), purchased certified standard.
smaller mill equipped with the 20-mesh or <1000-µm screen
and cryogenically ground again before analysis. Again the final
8.2 Liquid Nitrogen, plant grade (R-3, S-3).
sample should be thoroughly homogenized.
9. Calibration and Standardization 10.2 Pellets—May be cryogenically ground in a small
NOTE 1—The following procedure should be performed and recorded
grinding mill using liquid nitrogen. The final sample should be
once every three months.
thoroughly homogenized before sampling for analysis.
9.1 Break open a certified AA standard ampule (ampules
NOTE 5—Samples, either preforms, plaques, or pellets, should be
must be stored in a refrigerator) or prepare AA standard by the
chilled in the liquid nitrogen for several minutes until the liquid nitrogen
attached supplemental procedure. (See Appendix X5.) stops boiling and then dropped immediately into the grinder. Sample
F2013 − 10 (2016)
should be sufficiently ground in a few seconds. The grinder should not be
12. Calculation
allowed to operate more than 20 to 30 s as in such cases undesirable
12.1 The AA response factor is calculated as described in
sample heating can occur.
9.11 and 9.12. The ppm of AA can be calculated manually by
multiplying the response factor and the area of the AA peak,
11. Procedure
and then dividing this number by the sample weight in the vial
NOTE 6—Refer to the general operating manual for gas chromatograph,
the head-space sampler, and the series integrator for instructions in (in grams).
performing steps in this procedure.
13. Report
11.1 Adjust the gas chromatograph to the conditions speci-
fied in Appendix X1. Adjust the head-space sampler to the 13.1 Report the ppm or µg/g of AA to two decimal places.
conditions in Appendix X2. Set the series integrator to the
14. Precision and Bias
conditions in Appendix X3.
14.1 The following was taken from work completed by the
11.2 Sample Analysis:
International Society of Beverage Technologists (ISBT) sub-
11.2.1 Place 2 to 3 of polymer pellets (or crushed preform)
committee concerning standardization of method to determine
into a small Dewar flask.
residual AA in PET.
11.2.2 Cover the polymer with 20 to 40 mL of liquid
14.2 The number of laboratories, materials, and determina-
nitrogen.
tions in this study meets the minimum requirements for
11.2.3 Allow the polymer to chill under the liquid nitrogen
determining precision in accordance with Practice E691. A
for approximately 3 min (or until most of the liquid N2 has
complete report is on file at ASTM Headquarters.
evaporated).
11.2.4 Turn on the Wiley mill equipped with a 800 to
14.3 This round robin was conducted by having one labo-
1000-µm screen.
ratory mold PET preforms on a 48-cavity injection molding
11.2.5 Slowly pour the remaining liquid nitrogen from the machine and selecting 6 of those cavities as the sample set.
Dewar flask through the Wiley mill, followed by the chilled Even though these preforms all came from one PET sample
polymer sample (tapping the sample may be required). (material), each cavity has its own unique AA value, and thus,
were treated as six different materials. Also, two different types
11.2.6 Collect the ground polymer in a small glass jar or
of precision and bias were calculated, one based on each
small manila envelope.
laboratory using their own calibration standard solution and
11.2.7 Turn off the Wiley mill and clean it with a vacuum
another when each laboratory calibrated with a “common”
cleaner.
calibration standard.
11.2.8 Allow the ground polymer sample to come to room
Practice E691 Study Minimum
temperature (approximately 10 min).
Laboratories: 6 6
11.2.9 Weigh approximately 0.2000 (6 0.0200) g, recorded
Materials: 6 4
to the nearest 0.0001 g, into a 20-mL head-space vial. Determinations: 3 2
11.2.10 Place a septum (with TFE-fluorocarbon side down
14.4 Precision and Bias With Each Laboratory Using Their
towards the inside of the vial) on the vial. Place an aluminum
Own Calibration Standard—Precision, characterized by
cap on top of the septum, and crimp the cap with a crimper repeatability, Sr and r, and reproducibility, SR and R, has been
UNTIL THE CAP CANNOT BE TURNED. Remove the
determined for the materials to be as follows:
center piece of the aluminum cap (if it exists).
Materials Average Sr SR r R
Material A 5.21 0.1812 0.6403 0.5074 1.7928
11.2.11 Place the vial in the appropriate position in the
Material B 6.25 0.4060 0.7464 1.1368 2.0899
head-space sampler.
Material C 6.37 0.2880 0.6713 0.8066 1.8796
11.2.12 Set up head space sampler and a GC acquisition Material D 7.21 0.3285 0.7743 0.9198 2.1680
Material E 7.01 0.4217 0.8350 1.1808 2.3380
program condition as listed in Table X1.1 and Table X2.1,
Material F 5.88 0.3930 0.7168 1.1003 2.0071
following instrument operating instructions from manufacturer.
14.4.1 Since the materials used in this study are all from one
11.2.13 The head-space sampler will heat the sample for 60
specific type of material (PET), but have different AA levels
min at 150°C and then automatically inject the head-space gas
because they are from different cavities, it makes more sense to
and start the gas chromatograph and integrator or data acqui-
have one set of precision values rather than one for each cavity.
sition software.
This will be derived by squaring each Sr and SR, averaging
11.2.14 The final report will appear on the integrator or the
2 2
each of Sr and SR across materials and taking the square
data system when the GC is finished.
root.
11.2.15 Determine the peak area for the AA from integrator
Sr SR r R
or data acquisition software.
0.3466 0.7335 0.9705 2.0538
11.2.16 To determine the mass of AA from the sample, area
14.4.1.1 Standard Deviation (Sr)—Sr is the square root of
of AA multiplied by response factor.
the average within laboratory variance.
11.2.17 To determine the concentration in ppm of AA in the
polymer sample, divide the mass of AA (reported in 11.2.16)
by the sample weight in the vial (recorded in 11.2.9 as grams 4
Supporting data have been filed at ASTM International Headquarters and may
of polymer). be obtained by requesting Research Report RR:F02-1015.
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: F2013 − 10 F2013 − 10 (Reapproved 2016)
Standard Test Method for
Determination of Residual Acetaldehyde in Polyethylene
Terephthalate Bottle Polymer Using an Automated Static
Head-Space Sampling Device and a Capillary GC with a
Flame Ionization Detector
This standard is issued under the fixed designation F2013; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers a gas chromatographic procedure for the determination of the ppm residual acetaldehyde (AA)
present in poly(ethylene terephthalate) (PET) homo-polymers and co-polymers which are used in the manufacture of beverage
bottles. This includes sample types of both amorphous and solid-stated pellet and preform samples, as opposed to the bottle test,
Test Method D4509, an acetaldehyde test requiring 24 h of desorption time at 23°C into the bottle headspace and then the
concentration of the headspace quantified by a similar GC method.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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 and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D4509 Test Methods for Determining the 24-Hour Gas (AIR) Space Acetaldehyde Content of Freshly Blown PET Bottles
(Withdrawn 2004)
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Terminology
3.1 The terms employed in this test method are commonly used in normal laboratory practice and require no special comment.
4. Summary of Test Method
4.1 A specified size (< 1000 μm) of granulated sample is weighed into a 20-mL head-space vial, sealed, and then heated at
150°C for 60 min. After heating, the gas above the sealed sample of PET polymer is injected onto a capillary GC column. The
acetaldehyde is separated, and the ppm of acetaldehyde is calculated.
5. Significance and Use
5.1 This test method is of particular use as a quality control tool for a molding or synthesis operation. Acetaldehyde is a volatile
degradation product generated during melt processing of PET. Thus, it becomes trapped in the sidewalls of a molded article and
desorbs slowly into the contents packaged therein. In some foods and beverages AA can impart an off-taste that is undesirable, thus,
it is important to know its concentration in PET articles that are to be used in food contact applications.
5.2 The desorption conditions of 150 C for 60 min are such that no measurable AA is generated by the sample during the
desorption process.
This test method is under the jurisdiction of ASTM Committee F02 on Flexible Barrier Packaging and is the direct responsibility of Subcommittee F02.15 on
Chemical/Safety Properties.
Current edition approved Oct. 1, 2010May 1, 2016. Published October 2010June 2016. Originally approved in 2000. Last previous edition published in 20052010 as
F2013 – 05.F2013 – 10. DOI: 10.1520/F2013-10.10.1520/F2013-10R16.
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 ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2013 − 10 (2016)
6. Sources of Error
6.1 A bias is known to exist if the ratio of sample mass (mg) to head-space vial volume (mL) exceeds a value of ten.
6.2 Acetaldehyde is very volatile and must be handled carefully to avoid sample loss during the calibration procedure. Storing
the standard vials in a refrigerator (4 6 2°C) is a must to minimize the error due to volatility.
6.3 Failure to achieve a tight seal on the head-space vial will result in the loss of acetaldehyde during storage and desorption,
producing a false low value.
6.4 Failure to grind the sample to the appropriate particle size may lead to a false low value for residual AA due to the increased
path length for desorption.
6.5 Samples submitted for “residual AA measurement” should be stored in a freezer (< –10°C) until they are tested. Failure to
do so can result in lower than expected results.
6.6 Excessive grinding of samples can cause residual AA contained therein to be desorbed. Extensive excessive grinding can
lead to actual melting of the polymer and AA generation. Samples which have been chilled in liquid nitrogen properly should only
be in the grinder for ;30 s or less.
7. Apparatus
7.1 Gas Chromatograph, equipped with a flame ionization detector.
7.2 Integrator or a PC with data acquisition software.
7.3 Head-Space Sampler—(a static head-space sampler).
7.4 Column, 30-m by 0.53-mm inside diameter (DVB porous megabore capillary column or equivalent).
7.5 Vials, 20-mL, head-space, with 20-mm septa, 20-mm aluminum caps, and crimper for 20-mm caps.
7.6 Crimper, 20-mm.
7.7 Decrimper, 20-mm.
7.8 Wiley Mill, equipped with an 800 to 1000-μm screen, or equivalent.
7.9 Syringe, (gas tight) calibrated, with certificate of calibration.
7.10 Small Vacuum Cleaner, with hose attachment for cleaning.
7.11 Analytical Balance, capable of accurately weighing to at least 60.0001 g.
7.12 Hammer.
7.13 Air for EID.
7.14 Helium 99.9995 % purity as carrier gas.
7.15 Hydrogen 99.9995 % purity for flame ionization detector (FID) or can be used as carrier gas.
7.16 Spatular.
7.17 Dewer flask.
7.18 Glass jar or manila envelope.
7.19 Wipe paper or tissue.
7.20 Digital syringe, equipped with a 10-L glass syringe.
8. Reagents and Materials
8.1 Acetaldehyde (AA), 500 ppm AA in water (or 1000 ppm), purchased certified standard.
8.2 Liquid Nitrogen, plant grade (R-3, S-3).
9. Calibration and Standardization
NOTE 1—The following procedure should be performed and recorded once every three months.
9.1 Break open a certified AA standard ampule (ampules must be stored in a refrigerator) or prepare AA standard by the attached
supplemental procedure. (See Appendix X5.)
9.2 Using the syringe, fill it by placing the tip in the liquid standard and quickly moving the plunger up and down several time
to evacuate any bubbles, then pull the plunger back past the 2.000-μL mark to 2.200 to 2.250 μL.
9.3 Wipe the syringe needle with a tissue.
9.4 Depress the plunger until the digital readout is 2.000 μL.
F2013 − 10 (2016)
9.5 Smear the excess liquid that is on the syringe tip on the OUTSIDE of the headspace vial.
9.6 Place the syringe inside of the vial so that the tip just touches the bottom of the vial.
9.7 Quickly inject the liquid standard into the vial and swirl the syringe tip around the inside of the vial to smear all liquid on
the vial walls.
9.8 Remove the syringe and IMMEDIATELY cap the vial.
9.9 Calculate the weight of AA based on the standard’s certified value and a 2.000-μL injection volume.
NOTE 2—Acetaldehyde is very volatile. The AA ampules must be stored in a refrigerator, and the standards prepared immediately after breaking open
an ampule.
9.10 Analyze the working standard by the procedure described in Section 11, starting with 11.2.11.
9.11 Calculate an AA response factor for the standard using the following equation:
response factor of AA 5 Wt of AA in µg/area of AA (1)
NOTE 3—Due to the error associated with the certified standard, 9.1 – 9.11 should be performed five times using five different standard ampules.
9.12 Average the five response factors obtained, and use this value for the sample analyses.
9.13 Manually enter the calculated response factor in the calibration list of the integrator or data system.
NOTE 4—During a series of sample analyses, a periodic check of instrument performance is recommended by placing a few liquid standard samples
throughout the sample set. If these values fall out of the acceptable range as specified by the certificate of analysis, recalibration (9.1 – 9.12) should be
performed.
10. Sample Preparation
10.1 Parisons or Preforms or Plaques—May be cryogenically ground whole, or can be broken into small pieces with a hammer
(using liquid nitrogen) and then ground with the aid of grinding mill equipped with a 20-mesh or <1000-μm screen. The grind
should be thoroughly homogenized before sampling for AA. If the appropriate size screen is not available on the large grinding
mill, then it is suggested that the sample be ground to 3 to 6 mm on the large mill and the sample thoroughly homogenized. A
portion can then be taken to a smaller mill equipped with the 20-mesh or <1000-μm screen and cryogenically ground again before
analysis. Again the final sample should be thoroughly homogenized.
10.2 Pellets—May be cryogenically ground in a small grinding mill using liquid nitrogen. The final sample should be
thoroughly homogenized before sampling for analysis.
NOTE 5—Samples, either preforms, plaques, or pellets, should be chilled in the liquid nitrogen for several minutes until the liquid nitrogen stops boiling
and then dropped immediately into the grinder. Sample should be sufficiently ground in a few seconds. The grinder should not be allowed to operate more
than 20 to 30 s as in such cases undesirable sample heating can occur.
11. Procedure
NOTE 6—Refer to the general operating manual for gas chromatograph, the head-space sampler, and the series integrator for instructions in performing
steps in this procedure.
11.1 Adjust the gas chromatograph to the conditions specified in Appendix X1. Adjust the head-space sampler to the conditions
in Appendix X2. Set the series integrator to the conditions in Appendix X3.
11.2 Sample Analysis:
11.2.1 Place 2 to 3 of polymer pellets (or crushed preform) into a small Dewar flask.
11.2.2 Cover the polymer with 20 to 40 mL of liquid nitrogen.
11.2.3 Allow the polymer to chill under the liquid nitrogen for approximately 3 min (or until most of the liquid N2 has
evaporated).
11.2.4 Turn on the Wiley mill equipped with a 800 to 1000-μm screen.
11.2.5 Slowly pour the remaining liquid nitrogen from the Dewar flask through the Wiley mill, followed by the chilled polymer
sample (tapping the sample may be required).
11.2.6 Collect the ground polymer in a small glass jar or small manila envelope.
11.2.7 Turn off the Wiley mill and clean it with a vacuum cleaner.
11.2.8 Allow the ground polymer sample to come to room temperature (approximately 10 min).
11.2.9 Weigh approximately 0.2000 (6 0.0200) g, recorded to the nearest 0.0001 g, into a 20-mL head-space vial.
11.2.10 Place a septum (with TFE-fluorocarbon side down towards the inside of the vial) on the vial. Place an aluminum cap
on top of the septum, and crimp the cap with a crimper UNTIL THE CAP CANNOT BE TURNED. Remove the center piece of
the aluminum cap (if it exists).
11.2.11 Place the vial in the appropriate position in the head-space sampler.
11.2.12 Set up head space sampler and a GC acquisition program condition as listed in Table X1.1 and Table X2.1, following
instrument operating instructions from manufacturer.
F2013 − 10 (2016)
11.2.13 The head-space sampler will heat the sample for 60 min at 150°C and then automatically inject the head-space gas and
start the gas chromatograph and integrator or data acquisition software.
11.2.14 The final report will appear on the integrator or the data system when the GC is finished.
11.2.15 Determine the peak area for the AA from integrator or data acquisition software.
11.2.16 To determine the mass of AA from the sample, area of AA multiplied by response factor.
11.2.17 To determine the concentration in ppm of AA in the polymer sample, divide the mass of AA (reported in 11.2.16) by
the sample weight in the vial (recorded in 11.2.9 as grams of polymer).
12. Calculation
12.1 The AA response factor is calculated as described in 9.11 and 9.12. The ppm of AA can be calculated manually by
multiplying the response factor and the area of the AA peak, and then dividing this number by the sample weight in the vial (in
grams).
13. Report
13.1 Report the ppm or μg/g of AA to two decimal places.
14. Precision and Bias
14.1 The following was taken from work completed by the International Society of Beverage Technologists (ISBT)
subcommittee concerning standardization of method to determine residual AA in PET.
14.2 The number of laboratories, materials, and determinations in this study meets the minimum requirements for determining
precision in accordance with Practice E691. A complete report is on file at ASTM Headquarters.
14.3 This round robin was conducted by having one laboratory mold PET preforms on a 48-cavity injection molding machine
and selecting 6 of those cavities as the sample set. Even though these preforms all came from one PET sample (material), each
cavity has its own unique AA value, and thus, were treated as six different materials. Also, two different types of precision and
bias were calculated, one based on each laboratory using their own calibration standard solution and another when each laboratory
calibrated with a “common” calibration standard.
Practice E691 Study Minimum
Laboratories: 6 6
Materials: 6 4
Determinations: 3 2
14.4 Precision and Bias With Each Laboratory Using Their Own Calibration Standard—Precision, characterized by
repeatability, Sr and r, and reproducibility, SR and R, has been determined for the materials to be as follows:
Materials Average Sr SR r R
Material A 5.21 0.1812 0.6403 0.5074 1.7928
Material B 6.25 0.4060 0.7464 1.1368 2.0899
Material C 6.37 0.2880 0.6713 0.8066 1.8796
Material D 7.21 0.3285 0.7743 0.9198 2.1680
Material E 7.01 0.4217 0.8350 1.1808 2.3380
Material F 5.88 0.3930 0.7168 1.1003 2.0071
14.4.1 Since the materials used in this study are all from one specific type of material (PET), but have different AA levels
because they are from different cavities, it makes more sense to have one set of precision values rather than one for each cavity.
2 2
This will be derived by
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