1、Designation: D7768 12Standard 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 adoption or, in the c
2、ase 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 volatile compounds o
3、f 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 be added to the me
4、thod 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 (Test MethodD2369).1
5、.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 to establish appro
6、-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Some specifichazards statements are given in Section 7 on Hazards.2. Referenced Documents2.1 ASTM Standards:2D1475 Test Method For Density of Liquid Coatings, Inks,and Related ProductsD2369 T
7、est Method 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 Coa
8、tingsD4017 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 Chromatograp
9、hD7358 Test 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 E
10、B2-butoxyethanol; 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 c
11、omponents 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 ofaceto
12、ne containing an internal standard is added to the sealedvial and the contents 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 e
13、xtraction solvent. Using theprovisions of Practice D3960, the VOC content of coatings measured in1This test method is under the jurisdiction of ASTM Committee on Paint andRelated Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.21 on Chemical Analysis of Pain
14、ts and Paint Materials.Current edition approved August 1, 2012. Published October 2012. DOI:10.1520/D776812.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the stan
15、dards 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 States1g/L minus water, or other units, may be determined. Since the deter
16、mi-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 indirectly in the application of Practice D3960. Since preci-sion is better for the determ
17、ination 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 are present are:VOC 5fVOCDP!1 2 12 fNV2 fVOC!DPDW! #(1)orVOC 5fVOCDP!12 fWDPDW! #(2)where
18、: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 identification of thevolatile compounds present in a coating (Note 3).NOTE 3The analyst should con
19、sult MSDS 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 content of coatings, precision tends to be poor forwaterborne coatings because the VOC weight f
20、raction 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. Apparatus6.1 Gas Chromatograph, FID Detection with ElectronicData Acquisition SystemAny cap
21、illary 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 Standard FID Instrument Conditions:Detector Flame ionizationColumns Primary column: 30 m by
22、 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 flowSplit Ratio 50 to 1Temperatures, CInlet 260CDetector 270CInitial 50C for 4 minRate 20C per min
23、 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 PDMS isavailable by the designations DB-1, SPB-1, HP-1, AT-1, BP-1, CP Sil 5CB, Rtx-1. The co
24、lumn 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 in all tests. Unless otherwise indicated, all reagents shallconform to the available spec
25、ifications 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 withoutlessening the accuracy of the determination.7.2 Carrier Gas, helium of 99.995 % or hi
26、gher 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 part numbers: headspace vials, 51820837,crimp caps, 51834477, and crimper, 93010720, or e
27、quiva-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 Analysis9.1 Using a 100 mL volumetric flask, make up a concen-trated internal standard solut
28、ion 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 dilution techniques, dilutethe concentrated internal standard solution to give a workingi
29、nternal 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 the density of acetone (0.79g/mL).9.3 Determine the density of the individual components o
30、fthe 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 and mix using a spatula orpaint shaker. Immediately after mixing, transfer approximately1
31、00 mg of the mixture to a 20 mL headspace vial and weigh to0.1 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 coating4Carbowax is a registered trademark of The Dow Chemical Compa
32、ny.5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, 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 Pharmac
33、opeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D7768 122mixture evenly over the bottom surface of the vial. Prepare twomore samples in the same way.9.4 Determine the volatile content of the multi-componentmixture prepared in 9.3 using Test Method D2369 immediat
34、elyafter 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 glass syringe, add 3 to 4 mL of theworking internal standard solution from 9.2 to each of thecoole
35、d 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.9.5 Chromatograph the solution in 9.4 by injecting 1 Linto the PMPS capillary column using the sta
36、ndard 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 thecoating using the relationship:%X 5AA!MI!100!AI!RF!MC!(3)where:X = one of several possible volatile com
37、pounds 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 5Analytes may be identified using information available fromproduct data sheets, MSDS, GC/MS, or FID rete
38、ntion time comparisonwith known 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 componentsand the internal standard (EGDE) by weighing approximately1 g (to 0.1 mg) of each into an app
39、ropriate 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 solution in 10.2 by injecting 1 Linto the PMPS column using the chromatographic conditionsgiven in
40、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 analyte,MI = weight of internal standard,AI = area of internal standard, andMA = weight of analyte.11.
41、 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 aCarbowax capillary column.11.2 Using a PMPS column and the chromatographic con-ditions of 6.2, certain
42、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 Results12.1 Prepare a table (as indicated below) that containsinformation on each of the VOC species
43、 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 theweight % for unknown VOCs.13. Alternate Identification Methods13.1 The use of GC/MS for vola
44、tile 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(SPDE) and dynamic headspace analysis have also been usedsuccessfully to identify volatile componen
45、ts. 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 isplaced into service.14. Precision and Bias14.1 A within laboratory study of total weight percen
46、t 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 percent VOC content of 4.16 to 9.40.14.2 Precision statistics were calculated for the total weightpe
47、rcent 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. The95 % confidence limit for the difference b
48、etween two suchaverages is 12.0 % of the test result.14.4 BiasBias has not been determined.15. Keywords15.1 gas chromatography; multicomponent VOC analysis;waterborne multicomponent coating analysisD7768 123TABLE 1 Retention Times (in Minutes) and FID Relative Response Factors (RRF) of Possible Vola
49、ile Organic Compounds and ExemptCompounds in Waterborne Multi-Component Coatings Using the Chromatographic FID Conditions Described in 6.2Retention Time, minCompound RRF PMPS Carbowax PDMSmethanol 0.66 2.35 5.16 1.97ethanol 1.00 2.75 5.85 2.08acetone 1.02 3.12 3.93 2.212-propanol 1.02 3.13 5.71 2.19t-butyl alcohol 3.42methyl acetate 0.60 3.59 4.1 2.311-propanol 3.82 7.91 2.44vinyl acetate 4.40methyl ethyl ketone 1.25 4.74 5.24 2.72-butanol 1.18 4.78 7.63 2.72ethyl acetate 0.83 5.05tetrahydrofuran (THF) 5.31 4.65 3.05isobutyl alcohol
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