ASTM F2013-00
(Test Method)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
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
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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.
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.
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Designation: F 2013 – 00
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 F 2013; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope of PET. Thus, it becomes trapped in the sidewalls of a molded
article and desorbs slowly into the contents packaged therein.
1.1 This test method covers a gas chromatographic proce-
In some foods and beverages AA can impart an off-taste that is
dure for the determination of the ppm residual acetaldehyde
undesirable, thus, it is important to know its concentration in
(AA) present in poly(ethylene terephthalate) (PET) homo-
PET articles that are to be used in food contact applications.
polymers and co-polymers which are used in the manufacture
5.2 The desorption conditions of 150 C for 60 min are such
of beverage bottles. This includes sample types of both
that no measurable AA is generated by the sample during the
amorphous and solid-stated pellet and preform samples.
desorption process.
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
6. Sources of Error
responsibility of the user of this standard to establish appro-
6.1 A bias is known to exist if the ratio of sample mass (mg)
priate safety and health practices and determine the applica-
to head-space vial volume (mL) exceeds a value of ten.
bility of regulatory limitations prior to use.
6.2 Acetaldehyde is very volatile and must be handled
2. Referenced Documents carefully to avoid sample loss during the calibration procedure.
Storing the standard vials in a refrigerator is a must to
2.1 ASTM Standards:
minimize the error due to volatility.
D 4509 Test Method for Determining the 24-Hour Gas (Air)
6.3 Failure to achieve a tight seal on the head-space vial will
Space Acetaldehyde Content of Freshly Blown PET
result in the loss of acetaldehyde during storage and desorp-
Bottles
tion, producing a false low value.
3. Terminology 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
3.1 The terms employed in this test method are commonly
increased path length for desorption.
used in normal laboratory practice and require no special
6.5 Samples submitted for 8residual AA measurement’
comment.
should be stored in a freezer until they are tested. Failure to do
4. Summary of Test Method
so can result in lower than expected results.
6.6 Excessive grinding of samples can cause residual AA
4.1 A specified size (800 to 1000 μm) of granulated sample
contained therein to be desorbed. Extensive excessive grinding
is weighed into a 20-mL head-space vial, sealed, and then
can lead to actual melting of the polymer and AA generation.
heated at 150°C for 60 min. After heating, the gas above the
Samples which have been chilled in liquid nitrogen properly
sealed sample of PET polymer is injected onto a capillary GC
should only be in the grinder for ;30 s or less.
column. The acetaldehyde is separated, and the ppm of
acetaldehyde is calculated.
7. Apparatus
5. Significance and Use
7.1 Gas Chromatograph, Hewlett-Packard 6890 series
7.2 Integrator, Hewlett-Packard Model 6890 series, H-P
5.1 This test method is of particular use as a quality control
ChemStation, H-P LAN.
tool for a molding or synthesis operation. Acetaldehyde is a
7.3 Head-Space Sampler, Hewlett-Packard 7694.
volatile degradation product generated during melt processing
1 3
This test method is under the jurisdiction of ASTM Committee F02 on Flexible Hewlett-Packard apparatus, website: hewlett-packard.com, was used in the
Barrier Materials and is the direct responsibility of Subcommittee F02.30 on Test development of this standard. If you are aware of alternative suppliers, please
Methods. provide this information to ASTM headquarters. Your comments will receive careful
Curren edition approved April 10, 2000. Published August 2000. consideration at a meeting of the responsible technical committee, which you may
Annual Book of ASTM Standards, Vol 08.03. attend.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
F 2013
7.4 Column, 30-m by 0.53-mm i.d. (megabore capillary 9.4 Depress the plunger until the digital readout is 2.000 μL.
column). 9.5 Smear the excess liquid that is on the syringe tip on the
7.5 Vials, 20-mL, head-space, with 20-mm septa, 20-mm OUTSIDE of the headspace vial.
aluminum caps, and crimper for 20-mm caps 9.6 Place the syringe inside of the vial so that the tip just
7.5.1 Vials: touches the bottom of the vial.
Perkin-Elmer Part Numer 0105–0129 , or Kimble Glass Inc. 9.7 Quickly inject the liquid standard into the vial and swirl
Part Number 60827A-2375 , or Hewlett-Packard Part Number the syringe tip around the inside of the vial to smear all liquid
5182–0837 . on the vial walls.
7.5.2 Septa: 9.8 Remove the syringe and IMMEDIATELY cap the vial.
Pierce Part Number 12720, or Hewlett-Packard Part Number 9.9 Calculate the weight of AA based on the standard’s
9301–0807. certified value and a 2.000-μL injection volume.
7.5.3 Caps:
NOTE 2—Acetaldehyde is very volatile. The AA ampules must be
Pierce Part Number 13214, or Hewlett-Packard Part Number
stored in a refrigerator, and the standards prepared immediately after
9301–0721.
breaking open an ampule.
7.6 Crimper, 20-mm, Wheaton Part Number 224303.
9.10 Analyze the working standard by the procedure de-
7.7 Decrimper, 20-mm, Kimble Part Number 69903–20.
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, calibrated, with certificate of calibration.
response factor of AA 5 Wt of AA in μg/area of AA (1)
7.10 Small Vacuum Cleaner, with host attachment for clean-
ing. NOTE 3—Due to the error associated with the certified standard,
9.1-9.11 should be performed five times using five different standard
7.11 Analytical Balance, capable of accurately weighing to
ampules.
at least 60.0001 g.
9.12 Average the five response factors obtained, and use this
7.12 Hammer.
value for the sample analyses.
8. Reagents and Materials
9.13 Manually enter the calculated response factor in the
calibration list of the Hewlett-Packard 6890 integrator or data
8.1 Acetaldehyde (AA), 500 ppm AA in water (or 1000
system.
ppm), purchased certified standard.
8.2 Liquid Nitrogen, plant grade (R-3, S-3).
NOTE 4—During a series of sample analyses, a periodic check of
instrument performance is recommended by placing a few liquid standard
9. Calibration and Standardization
samples throughout the sample set. If these values fall out of the
acceptable range as specified by the certificate of analysis, recalibration
NOTE 1—The following procedure should be performed and recorded
(9.1-9.12) should be performed.
once every three months.
10. Sample Preparation
9.1 Break open a certified AA standard ampule. (Ampules
must be stored in a refrigerator.)
10.1 Parisons or Preforms or Plaques—May be cryogeni-
9.2 Using the syringe, fill it by placing the tip in the liquid
cally ground whole, or can be broken into small pieces with a
standard and quickly moving the plunger up and down several
hammer (using liquid nitrogen) and then ground with the aid of
time to evacuate any bubbles, then pull the plunger back past
grinding mill equipped with a 20 mesh or 850 μm screen. The
the 2.000-μL mark to 2.200 to 2.250 μL.
grind should be thoroughly homogenized before sampling for
9.3 Wipe the syringe needle with a tissue.
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 s
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