1、Designation: D 4747 02Standard Test Method forDetermining Unreacted Monomer Content of Latexes UsingGas-Liquid Chromatography1This standard is issued under the fixed designation D 4747; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, 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 This test method covers the determination of freemonomer content of acrylic latexes. Monomers that hav
3、e beensuccessfully determined by this procedure include n-butylmethacrylate, n-butyl acrylate, styrene, and methyl methacry-late. The determination of other monomers has not beenevaluated, but this test method is believed to be applicable. Theestablished working range of this test method is from 100
4、 to1000 g/g, but there is no reason to believe it will not workoutside of this range, provided that appropriate dilutions andadjustments in specimen size are made.1.2 The volatile composition of acrylic latexes is expectedto change with time and environmental factors. This timedependence of the dete
5、rmination may be seen as an artificiallylarge deviation of results, making the method mostly appli-cable for in-house quality control, where sampling and analysisconditions can be better controlled.1.3 The values stated in inch-pound units are to be regardedas the standard. The values given in paren
6、theses are forinformation only.1.4 This standard does not purport to address all 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 limitatio
7、ns prior to use. See Section 7 forspecific hazard statements.2. Referenced Documents2.1 ASTM Standards:D 3980 Practice for Interlaboratory Testing of Paint andRelated Materials2E 260 Practice for Packed Column Gas Chromatography33. Summary of Test Method3.1 A suitable aliquot of the latex is interna
8、lly standardizedwith isobutyl acrylate, diluted with water, and then injectedinto a gas chromatographic column containing a packingmaterial coated with a stationary phase that separates theinternal standard and monomers in question from each otherand from other volatile compounds.4. Significance and
9、 Use4.1 Excessive amounts of unreacted monomer may causeconcerns relating to toxicity and odor. This test method isdesigned to measure the unreacted monomer content of latexes.The results may be used to monitor the extent of polymeriza-tion during manufacture, as well as to establish maximumunreacte
10、d monomer content for regulatory purposes.5. Apparatus5.1 Gas Chromatograph, any gas-liquid chromatographicinstrument having a flame ionization detector and lineartemperature programming. An injection port using replacableglass liners to facilitate periodic removal of accumulatedresidues is recommen
11、ded.5.2 Column, 2 by 2-mm inside diameter glass or 6 ft by18-in. outside diameter steel tubing, packed with 10 % byweight of a 2-nitroterephthalic acid derivative of a syntheticpolyester wax on 100/120 mesh acid washed, silane treateddiatomaceous earth.4A column of equivalent or superiorperformance
12、may also be used.5.3 RecorderA recording potentiometer with a full-scaledeflection of 10 mV, a full-scale response time of2sorless,and a maximum noise level of 60.03 % of full scale (seePractice E 260).5.4 Liquid Charging Devices, microsyringe, 10-L capacityor an automatic liquid sampling device.5.5
13、 Dropper Pipets, glass, disposable.5.6 Vials, approximately 7-mL capacity, with caps. Open topscrew cap vials fitted with polytetrafluoroethylene/siliconesepta are preferred.5.7 Autosampler Vials, 2-mL capacity (optional).5.8 Analytical Balance, accurate to 0.1 mg.6. Reagents6.1 Purity of ReagentsRe
14、agent grade chemicals shall be1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.Current edition approved Jan. 10, 2002.
15、Published March 2002.Originallypublished as D 4747 - 87. Last previous edition D 4747 - 87 (1996)1.2DiscontinuedSee1999 Annual Book of ASTM Standards.3Annual Book of ASTM Standards, Vol 03.06.4Columns prepared from the stationary phases and supports have been foundsuitable for this purpose and are a
16、vailable from scientific supply houses.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.used in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical
17、 Reagents of the American Chemical Society,where such specifications are available.5Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.6.2 Carrier Gas, helium of 99.995 % or hig
18、her purity. Highpurity nitrogen may also be used.6.3 Acetone, reagent grade.6.4 Isobutyl Acrylate (internal standard), 99+ % pure.NOTE 1Isobutyl acrylate was found to be a suitable internal standard,but any other monomer not found in the sample may be substituted. Theinternal standard chosen should
19、yield a clear chromatographic separation,and should be free of interferences.6.5 Monomers of Interest, 99+ % pure.7. Hazards7.1 Acrylic and methacrylic monomers are considered haz-ardous. Precautions should be taken to avoid inhalation andskin or eye contact with these chemicals. All sample prepara-
20、tions should be done in a well-ventilated area, such as a fumehood.8. Preparation of Apparatus8.1 Column ConditioningAttach one end of the column tothe inlet side of the instrument leaving the exit end of thecolumn disconnected. This prevents the contamination of thedetector due to column bleed. Set
21、 the helium flow rate at 30mL/min and purge the column at ambient temperature for 30min. Program the column oven from 50 to 220C at 2C/minand maintain at 220C overnight. In no case should thetemperature of the column be allowed to exceed 275C.8.2 After conditioning, connect the exit end of the colum
22、n tothe detector and establish the operating conditions required togive the desired separation (see Table 1). Allow sufficient timefor the instrument to reach equilibrium as indicated by a stablebaseline. Control the detector temperature so that it is constantto within 1C without thermostat cycling
23、which causes anuneven baseline. Adjust the carrier gas flow rate to a constantvalue.9. Calibration9.1 Determine the retention of each component expected tobe present by injecting small amounts either separately or inknown mixtures. Retention times should be determined eachday the method is used.9.2
24、StandardizationDetermine in duplicate the relativeresponse of the monomers of interest to the isobutyl acrylateinternal standard as follows:9.2.1 Weigh to 0.1 mg about 0.05 g of isobutyl acrylate andeach monomer of interest into a vial (5.6). Weigh approxi-mately5gofacetone into the vial and mix wel
25、l.9.2.2 Weigh approximately 0.05 g of the solution (9.2.1)into another vial, add approximately5gofacetone and mixwell.9.2.3 Inject a 1-L aliquot of the solution from 9.2.2 ontothe column and record the chromatogram. The elution order foracetone and each of the monomers using the conditions givenin T
26、able 1 is shown in Fig. 1.9.2.4 Measure the peak areas of the individual componentsand calculate the relative response factor, RF, for the mono-mers of interest as follows:5“Reagent Chemicals, American Chemical Society Specifications,” Am. Chemi-cal Soc., Washington, DC. For suggestions on the testi
27、ng of reagents not listed bythe American Chemical Society, see “Reagent Chemicals and Standards,” by JosephRosin, D. Van Nostrand Co., Inc., New York, NY, and the “United StatesPharmacopeia.”TABLE 1 Instrument ConditionsDetector flame ionizationAir flow 240 mL/minHydrogen flow 30 mL/minColumn (sugge
28、sted) 2 by 2 mm inside diameter glass, packed with10 %of a 2-nitroterephthalic acid derivative of Carbo-wax 20M on 100/120 mesh acid washed, silane-treated diatomaceous earth.Carrier gas, flow rate Helium, 30 mL/minTemperatures:Injection port 250CDetector block 250CColumnInitial 80CHold time 4 minPr
29、ogram rate 8C/minFinal 200C, or higher as needed (see 8.1)Final hold 10 min, or as neededInjection volume 2 LFIG. 1 Typical ChromatogramD 47472RF 5 W13 As!/Ws3 A1!where:RF = relative response factor for each monomer,A1= peak area produced by the monomer,As= peak area produced by the internal standar
30、d,W1= weight of monomer used for calibration (9.2.1), andWs= weight of internal standard (9.2.1).10. Procedure10.1 If the composition of the latex is not known or if theapproximate level of monomers in the latex is not known, apreliminary analysis must be performed by diluting approxi-mately 0.5 g o
31、f latex with approximately5gofwater andinjecting a 2-L aliquot into the chromatographic column.Using the same conditions as for standardization, record thepeaks of all components at attentuation settings that providemaximum peak heights. Use the relative retention times toidentify the monomers prese
32、nt. If the specimen has a compo-nent eluting at the same retention time as isobutyl acrylate,choose a different internal standard (Note 1).10.2 Prepare a dilute solution of the internal standard byweighing to 0.1 mg about 0.05 g of isobutyl acrylate and5gofacetone into a septum vial. Take care to mi
33、nimize losses due toevaporation. Prepare this solution fresh each day the method isused.10.3 Weigh to 0.1 mg an appropriate amount of sample intoa septum vial using Table 2 as a guide to specimen size. Alsoweigh to 0.1 mg 50 mg of the dilute solution prepared in 10.2into the vial. Add about 3 to5gof
34、water or acetone. Shake thevials on a wrist action shaker or other suitable device for 15min.NOTE 2The viscosity of a number of latexes increases upon theaddition of an organic solvent. If acetone (or another organic solvent) isfound to be compatible with the specimen, it should be used as the dilue
35、ntinstead of water. It should be kept in mind that some organic solvents mayinterfere with the chromatographic separation.10.4 Inject 2 L of the prepared solution (10.3) into thechromatographic column and record the chromatogram usingthe conditions as in 10.1. Measure the peak areas (Note 3) ofthe i
36、nternal standard and relevant monomers, multiplying eacharea by the appropriate factor to express the peak areas on acommon basis.NOTE 3Peak areas may be determined by any method that meets theprecision requirements of Section 12. Electronic integration is recom-mended for best results.10.5 Repeat p
37、rocedure in 10.3 through 10.4 and calculatethe mean values.11. Calculations11.1 The weight of the internal standard present in thediluted specimen (10.3) is calculated as follows:W45 W5/W6!W7(1)where:W4= weight of internal standard in diluted specimen in10.3,W5= weight of internal standard used to p
38、repare solutionin 10.2,W6= weight of acetone plus weight of internal standardused to prepare solution in 10.2, andW7= weight of the dilute internal standard solution (10.2)added to the specimen in 10.3.11.2 Calculate the concentration, C, of each monomerpresent in the latex sample from the results o
39、btained from 10.5as follows:C 5 A33 W43 RF!/W83 A4!# 3 106(2)where:C = concentration of free monomer, g/g,A3= peak area produced by the monomer,A4= peak area produced by the internal standard,RF = relative response factor for each monomer (9.2.4),W4= weight of internal standard (11.1), andW8= specim
40、en weight (10.3).12. Precision and Bias612.1 PrecisionIn an interlaboratory study of the methodby five laboratories using four samples, the within-laboratorycoefficient of variation was found to be 16.8 % relative at 11degrees of freedom and the between-laboratories coefficient ofvariation was 18.1
41、% relative at 8 degrees of freedom. Basedon these coefficients, the following criteria should be used forjudging the acceptability of results at the 95 % confidence level(see Practice D 3980 and Note 4).12.1.1 RepeatabilityTwo results, each the mean of dupli-cate determinations, obtained by the same
42、 operator on differentdays should be considered suspect if they differ by more than52 % relative.12.1.2 ReproducibilityTwo results, each the mean of du-plicate determinations, obtained by operators in different labo-ratories should be considered suspect if they differ by morethan 59 % relative.NOTE
43、4Variation in results may be due to the changing compositionof the samples used for the study. This precision statement should be usedonly as a guide, since it represents only the magnitude of variation that ispossible, which will vary with time depending on the latex and theparticular monomers bein
44、g determined.12.2 BiasBias cannot be determined because there are nostandards for monomer content of latices.6Supporting data are available from ASTM International Headquarters. RequestRR: D011055.TABLE 2 Suggested DilutionsNOTE 1This table shall be used only as a guide. If the monomerconcentrations
45、 are outside the range given, appropriate adjustments mustbe made in terms of specimen size, dilution and amount of internalstandard added.Level ofFree MonomerExpected,g/gSpecimenSize,gDiluent,g250 2 3500 1 4750 0.7 4.31000 0.5 4.5D 4747313. Keywords13.1 analysis of monomers; acrylic latexes chromat
46、ography(subheading gas chromatography); gas chromatography; latexpaints; latex vehicles; styrene; trace monomers; unreactedmonomers in latexesASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of thi
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