1、Designation:D 4509 96Standard Test Methods forDetermining the 24-Hour Gas(AIR)Space AcetaldehydeContent of Freshly Blown PET Bottles1This standard is issued under the fixed designation D 4509;the number immediately following the designation indicates the year oforiginal adoption or,in the case of re
2、vision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 These test methods cover the 24-h gas-space acetalde-hyde(AA)content of freshly blown polyethylene tere
3、phthalate(PET)bottles.1.2 These test methods,containing internal or externalstandard calibration,are applicable to all PET bottles.1.3 The values stated in SI units are to be regarded as thestandard.NOTE1There is no similar or equivalent ISO standard.1.4 This standard does not purport to address all
4、 of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:D 883 Terminology Relating
5、 to Plastics2D 1193 Specification for Reagent Water3D 1600 Terminology for Abbreviated Terms Relating toPlastics2E 177 Practice for Use of the Terms Precision and Bias inASTM Test Methods4E 355 Practice for Gas Chromatography Terms and Rela-tionships4E 380 Practice for Use of the International Syste
6、m of Units(SI)(the Modernized Metric System)4E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method43.Terminology3.1 The gas chromatographic terms employed in these testmethods are those recommended by Practice E 355.3.2 Units,symbols,and abbreviations used
7、 in these testmethods are those recommended by Practice E 380.3.3 For further information on abbreviation,PET,refer toTerminology D 1600.3.4 Additional terms relative to plastics are explained inTerminology D 883.4.Summary of Test Methods4.1 A molded preform(any size)is blown into a bottle thatis pu
8、rged with nitrogen,capped,and aged.After 24 h,aheadspace gas sample is taken from the bottle,and the gassample is injected into a gas chromatograph for comparisonwith known external standards(Sections 9-11)or internalstandards(Sections 12-14).5.Significance and Use5.1 Before proceeding with these te
9、st methods,referenceshould be made to the specification of the material being tested.Any test specimens preparation,conditioning,dimensions,andtesting parameters covered in the materials specification,shalltake precedence over those mentioned in these test methods.Ifthere is no material specificatio
10、n,then the default conditionsapply.5.2 Acetaldehyde is a decomposition product of the poly-condensation reaction and is a by-product of melt processing ofpolyethylene terephthalate(PET).It adds undesirable flavor tosome beverages.5.3 The level of acetaldehyde in PET blown containers ismonitored by t
11、hese test methods.6.Apparatus6.1 Gas Chromatograph,with flame ionization detector,equipped with a six-port gas-sampling valve and a 5-mLgas-sampling loop for sampling the headspace of the beveragebottle,as shown in Fig.1.6.2 Any suitable system of peak integration can be used formeasurement of the a
12、cetaldehyde.6.3 Gas Sampling Apparatus as shown in Fig.1,including:6.3.1 Trap,25.4 mm(1 in.)outside diameter by 0.305 m(1ft)long containing 1 part silica-gel absorbant and 1 part 5Amolecular-sieve packing.6.3.2 Pressure-Vacuum Gage,030 psig and 30 in.Hg.6.4 Gastight GC Syringe,10 L.1These test metho
13、ds are under the jurisdiction of ASTM Committee D-20 onPlastics and are the direct responsibility of Subcommittee D20.70 on AnalyticalMethods(Section D20.70.03).This standard has been reviewed and the following items added:an ISOequivalency statement;a material specification reference statement;and
14、a KeywordsSection.Current edition approved August 10,1996.Published February 1997.2Annual Book of ASTM Standards,Vol 08.01.3Annual Book of ASTM Standards,Vol 11.01.4Annual Book of ASTM Standards,Vol 14.02.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959
15、,United States.6.5 Gastight GC Syringe,0 to 5.0 cc(internal standardmethod only).7.Reagents and Materials7.1 A 2.0 m by 6 mm outside diameter,4-mm insidediameter glass column,packed with Porapak Q or QS(100 to120 mesh)porous polymer or Tenax GC porous polymer(60 to80 mesh),packed into a 3.2 or 3.18
16、mm(18in.)outsidediameter by 3.66 m(12 ft)long stainless-steel tube.57.2 Acetaldehyde Standard Solution,prepared and analyzedby the procedure described in Annex A1.7.3 Acetaldehyde/Propionaldehyde Standard Solution,pre-pared by Annex A2(internal standard method only).7.4 Phenolic Polymer Bottle Cap,28 mm outside diameter,containing a 6.35-mm(14-in.)hole drilled in the top and snuglyfitted with a seal cut from 1.59-mm(116-in.)butyl rubber andlined with a liner cut from 0.08-mm(0.003-in.)fluoropoly
