1、Designation: D7768 12 (Reapproved 2018)Standard Test Method forSpeciated Organic Volatile Content of Waterborne Multi-Component Coatings by Gas Chromatography1This standard is issued under the fixed designation D7768; the number immediately following the designation indicates the year oforiginal ado
2、ption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method is for the determination of the indi-vidual organic vo
3、latile compounds of waterborne multi-component coatings using gas chromatography (see Note 1).1.2 The method has also been used successfully to deter-mine the speciated volatile organic content of solvent-bornemulti-component coatings. Work is continuing to develop thisaspect of the method and will
4、be added to the method at a laterdate.NOTE 1Currently there are no methods for the direct analysis of theVOC content of waterborne multi-component coatings. The VOC contentof solvent-borne multi-component coatings is determined directly by asimple weight loss determination of the mixed components (T
5、est MethodD2369).1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.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
6、to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Pri
7、nciples for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1475 Test Method for Density of Liquid Coatings, Inks,and Related ProductsD2369 Test Method
8、 for Volatile Content of CoatingsD3792 Test Method for Water Content of Coatings by DirectInjection Into a Gas ChromatographD3925 Practice for Sampling Liquid Paints and RelatedPigmented CoatingsD3960 Practice for Determining Volatile Organic Compound(VOC) Content of Paints and Related CoatingsD4017
9、 Test Method for Water in Paints and Paint Materialsby Karl Fischer MethodD6133 Test Method for Acetone, p-Chlorobenzotrifluoride,Methyl Acetate or t-Butyl Acetate Content of Solvent-borne and Waterborne Paints, Coatings, Resins, and RawMaterials by Direct Injection Into a Gas ChromatographD7358 Tes
10、t Method for Water Content of Paints by Quanti-tative Calcium Hydride Reaction Test KitE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Acronyms:3.1.1 EB2-butoxye
11、thanol; Butyl Cellosolve,3ethyleneglycol monobutyl ether3.1.2 EGDEethylene glycol diethyl ether3.1.3 FIDflame ionization detector3.1.4 GCgas chromatogaphy3.1.5 MSmass spectrometry3.1.6 SPDEsolid phase dynamic extraction3.1.7 SPMEsolid phase microextraction4. Summary of Test Method4.1 The components
12、are mixed, a sample of the mixture isweighed into a 20 mL headspace vial, the vial is sealed with acrimp cap, and the mixture is allowed to cure for 24 h or longerat ambient temperature. After the initial cure, the sample isheated for 30 min at 110C. After cooling, a known quantity ofacetone contain
13、ing an internal standard is added to the sealed1This 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 approve
14、d June 1, 2018. Published June 2018. Originallyapproved in 2012. Last previous edition approved in 2012 as D7768 12. DOI:10.1520/D7768-12R18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volu
15、me information, refer to the standards Document Summary page onthe ASTM website.3Butyl Cellosolve is a registered trademark of The Dow Chemical Company.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was dev
16、eloped in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1vial and the cont
17、ents are mixed. The solution containing theorganic volatile compounds is then analyzed by gas chro-matograhpy (Note 2).NOTE 2If the cured coating contains free amines, acetone may bereplaced with tetrahydrofuran (THF) as the extraction solvent. Using theprovisions of Practice D3960, the VOC content
18、of coatings measured ing/L minus water, or other units, may be determined. Since the determi-nation of weight percent VOC in the present method is by directmeasurement, either the water fraction (Test Method D3792 or TestMethod D4017) or the nonvolatile fraction (Test Method D2369) may bedetermined
19、indirectly in the application of Practice D3960. Since preci-sion is better for the determination of the nonvolatile content, this is thepreferred method for the indirect calculation of water content in thismethod. The equations for calculating regulatory VOC content when noexempt volatile compounds
20、 are present are:VOC 5fVOCDP!1 2 1 2 fNV2 fVOC!DP DW!#(1)orVOC 5fVOCDP!12 fWDP DW!#(2)where:DP,fNV,fVOC, and fw= coating density, nonvolatile fraction, VOCfraction, and water fraction, respectively.4.2 Direct GC/FID or GC/MS using solid phase microec-traction (SPME) may be used to facilitate identif
21、ication of thevolatile compounds present in a coating (Note 3).NOTE 3The analyst should consult SDS and product data sheets forpossible information regarding solvents which may be present in aparticular coating.5. Significance and Use5.1 In using the methods of Practice D3960 to measure theVOC conte
22、nt of coatings, precision tends to be poor forwaterborne coatings because the VOC weight fraction isdetermined indirectly. The present method first identifies andthen quantifies the individual VOCs directly. The total VOCweight fraction is obtained by adding the individual weightfraction values.6. A
23、pparatus6.1 Gas Chromatograph, FID Detection with ElectronicData Acquisition SystemAny capillary gas chromatographequipped with a flame ionization detector and temperatureprogramming capability may be used. Electronic flow control,which gives a constant carrier gas flow, is highly recom-mended.6.2 S
24、tandard FID Instrument Conditions:Detector Flame ionizationColumns Primary column: 30 m by 0.25 mm 5 % phenyl/95 %methyl siloxane (PMPS) (Note 4), 1.0 m film thicknessConfirmatory Column: 60 m by 0.25 mm Carbowax4(CW),0.50 m film thicknessCarrier Gas HeliumFlow Rate 1.0 mL per min, constant flowSpli
25、t Ratio 50 to 1Temperatures, CInlet 260CDetector 270CInitial 50C for 4 minRate 20C per min to 250C, hold 6 minNOTE 4The column designated as PMPS is commercially availablefrom several vendors by the following designations: DB-5, SPB-5, HP-5,AT-5, CP Sil 8CB, Rtx-5, BP-5. The column designated as PDM
26、S isavailable by the designations DB-1, SPB-1, HP-1, AT-1, BP-1, CP Sil 5CB, Rtx-1. The column designated as Carbowax is available by thedesignations Suplecowax 10, DB-Wax, HP-Wax, AT-Wax, CP-Wax 52CB. Rtx-Wax, BP-20.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused
27、 in all tests. Unless otherwise indicated, all reagents shallconform to the available specifications of the Committee onAnalytical Reagents of the American Chemical Society.5Othergrades may be used, provided it is first ascertained that thereagent is of sufficiently high purity to permit its used wi
28、thoutlessening the accuracy of the determination.7.2 Carrier Gas, helium of 99.995 % or higher purity.7.3 Acetone, HPLC grade.7.4 Ethylene Glycol Diethyl Ether (EGDE), 99 mole %.7.5 Fluorocarbon-faced Septum Vials, 20 mL and 40 mL,Headspace Vials (20 mL), Crimp Caps, and Cripmer, AgilentTechnologies
29、 part numbers: headspace vials, 51820837,crimp caps, 51834477, and crimper, 93010720, or equiva-lent.8. Column Conditioning8.1 The capillary columns should be conditioned accordingto the manufacturers recommendation. The columns may thenbe used indefinitely without further conditioning.9. Coating An
30、alysis9.1 Using a 100 mL volumetric flask, make up a concen-trated internal standard solution containing ethylene glycoldiethyl ether (EGDE) or other suitable internal standard inacetone at a concentration of approximately 1 g per 100 mLand known to the nearest 0.1 mg.9.2 Using standard quantitative
31、 dilution techniques, dilutethe concentrated internal standard solution to give a workinginternal standard solution such that the concentration is near 1mg per mL. Calculate the actual concentration. Convert theconcentration of the working internal standard solution frommg/mL to mg/g by dividing by
32、the density of acetone (0.79g/mL).9.3 Determine the density of the individual components ofthe multi-component coating using Test Method D1475. Con-vert the manufacturers recommended volume mix ratio to aweight mix ratio. Using a suitable container, prepare approxi-mately 100 to 200 g of the mixture
33、 and mix using a spatula orpaint shaker. Immediately after mixing, transfer approximately100 mg of the mixture to a 20 mL headspace vial and weigh to4Carbowax is a registered trademark of The Dow Chemical Company.5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society,
34、 Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D776
35、8 12 (2018)20.1 mg. Add a paper clip to the vial and then seal the vial witha crimp cap immediately after adding the coating mixture andpaper clip. Using an external magnet, spread the coatingmixture evenly over the bottom surface of the vial. Prepare twomore samples in the same way.9.4 Determine th
36、e volatile content of the multi-componentmixture prepared in 9.3 using Test Method D2369 immediatelyafter preparing the mixture. Allow the coating in the cappedvials from 9.3 to cure for a minimum of 24 h at ambienttemperature and then heat the vials for 30 min at 110C for 30min. Using a dedicated g
37、lass syringe, add 3 to 4 mL of theworking internal standard solution from 9.2 to each of thecooled headspace vials by injecting the solution into the cappedvial. Determine the weight of solution added to 0.1 mg. Mixthe contents by briefly shaking the contents followed bysonication for 15 to 30 min.9
38、.5 Chromatograph the solution in 9.4 by injecting 1 Linto the PMPS capillary column using the standard conditionsdescribed in 6.2. Adjust the split ratio to give well-definedchromatographic peaks. Identify the volatile compounds pres-ent (Note 5) and calculate the weight percent of each in thecoatin
39、g using the relationship:%X 5AA!MI!100!AI!RF!MC!(3)where:X = one of several possible volatile compounds in thecoating,RF = relative response factor of compound X,AA = peak area of compound X,MI = weight of internal standard,AI = peak area of internal standard, andMC = weight of coating.NOTE 5Analyte
40、s may be identified using information available fromproduct data sheets, SDS, GC/MS, or FID retention time comparison withknown compounds (see Table 1).10. Preparation of Standards10.1 After identification of the VOCs present in the coating(from 9.5), prepare a mixture of the identified pure compone
41、ntsand the internal standard (EGDE) by weighing approximately1 g (to 0.1 mg) of each into an appropriate vial and mix thecontents.10.2 Dilute a portion of the mixture from 10.1 with acetoneto give a solution with a concentration of each analyte ofapproximately 1 to 2 mg/mL.10.3 Chromatograph the sol
42、ution in 10.2 by injecting 1 Linto the PMPS column using the chromatographic conditionsgiven in 6.2. Calculate the relative response factors for each ofthe analytes relative to the EGDE internal standard using therelationship:RF 5AA* MIAI* MA(4)where:RF = relative response factor,AA = area of analyt
43、e,MI = weight of internal standard,AI = area of internal standard, andMA = weight of analyte.11. Chromatographic Resolution11.1 Acetone and isopropyl alcohol have nearly the sameretention time on a 5 % phenyl/95 % PDMS column and ifeither is found, their identities should be confirmed using aCarbowa
44、x capillary column.11.2 Using a PMPS column and the chromatographic con-ditions of 6.2, certain compounds co-elute. These include, andare not limited to: PM acetate/ethylbenzene and2-butoxyethanol(EB)/o-xylene. Separation may be obtained bychanging the chromatographic heating rate.12. Reporting Resu
45、lts12.1 Prepare a table (as indicated below) that containsinformation on each of the VOC species found.VOC Found GC Retention Time Weight % FoundTotal weight percent of all speciated VOCs =12.2 List VOCs that are not identified as unknown (UK) anduse the relative response factor of EGDE to calculate
46、 theweight % for unknown VOCs.13. Alternate Identification Methods13.1 The use of GC/MS for volatile compound identifica-tion is highly desirable. A convenient procedure is to samplethe headspace of the cured coating in one of the headspacevials using an SPME fiber. Solid phase dynamic extraction(SP
47、DE) and dynamic headspace analysis have also been usedsuccessfully to identify volatile components. Table 1 lists therelative retention times of a wide variety of compounds whichhave been found in various coatings. The retention times mustbe reconfirmed whenever a new or different capillary column i
48、splaced into service.14. Precision and Bias14.1 A within laboratory study of total weight percent VOCwas conducted in accordance with Practice E691 with threewaterborne multi-component materials. Three test results wereobtained for each material. The three coatings analyzed had arange in weight perc
49、ent VOC content of 4.16 to 9.40.14.2 Precision statistics were calculated for the total weightpercent VOC found in each of the three coatings and arepresented in Table 2. The term repeatability limit is used asspecified in Practice E177.14.3 95 % Repeatability Limit (within laboratory)Thewithin-laboratory coefficient of variation is 4.3 % relative. TheD7768 12 (2018)3TABLE 1 Retention Times (in Minutes) and FID Relative Response Factors (RRF) of Possible Volatile Organic Compounds and ExemptCompounds in Waterborne Multi-Component Coat
