1、Designation: D 2743 68 (Reapproved 2004)Standard Practices forUniformity of Traffic Paint Vehicle Solids by Spectroscopyand Gas Chromatography1This standard is issued under the fixed designation D 2743; the number immediately following the designation indicates the year oforiginal adoption or, in th
2、e case of revision, 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 practices provide general information on theinstrumental techniques available f
3、or detecting adulteration ornonuniformity of the chemical nature of the vehicle solids inpurchased lots of traffic paints by means of the individual orcombined use of infrared and ultraviolet spectroscopy and gaschromatography. The procedures given are applicable whentraffic paint is selected and pu
4、rchased on the basis of pre-qualification laboratory or road performance tests, or both, anda reference sample of the original paint so evaluated andselected is retained and compared with test samples represen-tative of subsequent purchased and delivered lots of such paintand which are required to b
5、e the same as the original referencesample.1.2 Although not specifically provided for in these prac-tices, the methods given may also be applied, with appropriatemodification, to evaluating the acceptability of traffic paintsthat have been purchased on the basis of composition specifi-cations. In su
6、ch cases, application is limited to the vehiclesolids as before, as well as the availability of a suitablestandard or range of standards representative of the vehiclesolids that are acceptable and with which samples of subse-quent delivered lots will be compared.1.3 The techniques provided are wholl
7、y adequate for detect-ing gross adulteration of the vehicle solids where completelydifferent drying oils, resins, or polymers, or combinations ofthese have been substituted for those originally contained in thereference sample. In cases of lesser adulteration or modifica-tion, these methods have bee
8、n found adequate for detectingvehicle solids, adulterations, or modifications as low as 5weight % of the vehicle solids.1.4 These techniques have been developed on the basis ofcooperative work with alkyd, chlorinated rubber-alkyd, andpoly(vinyl toluene) type paints involving the detection ofnonunifo
9、rmity when such extraneous materials as rosin, fishoil, hydrocarbon resin, and chlorinated paraffin have beenadded. The procedures given may be, but are not necessarilycompletely applicable to all other types of vehicle solids orextraneous additions, or both.1.5 The methods provided appear in the fo
10、llowing order:SectionMethod AInfrared Spectral Analysis of Total Vehicle Solids 10-12Method BInfrared Spectral Analysis of Unsaponifiable Matterfrom Vehicle Solids 13-15Method CGas Chromatographic Analysis of Oils and Oil AcidsSeparated from Vehicle Solids 16-18Method DUltraviolet Spectral Analysis
11、of Total Vehicle Solids19, 20, and211.6 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 limi
12、tations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1259 Test Methods for Nonvolatile Content of ResinSolutionsD 1397 Test Method for Unsaponifiable Matter in AlkydResins and Resin SolutionsD 2245 Test Method for Identification of Oils and Oil Acidsin Solvent-Reducible PaintsD 2372 Pra
13、ctice for Separation of Vehicle from Solvent-Reducible PaintsD 2621 Test Method for Infrared Identification of VehicleSolids from Solvent-Reducible PaintsE 105 Practice for Probability Sampling of MaterialsE 131 Terminology Relating to Molecular Spectroscopy3. Terminology3.1 For definitions of terms
14、 and symbols, refer to Terminol-ogy E 131.1These practices are under jurisdiction of ASTM Committee D01 on Paint andRelated Coatings, Materials, and Applications and are the direct responsibility ofSubcommittee D01.44 on Traffic Coatings.Current edition approved June 1, 2004. Published June 2004. Or
15、iginallyapproved in 1968. Last previous edition approved in 1998 as D 2743 68 (1998)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 standards Document Summary p
16、age onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Summary of Methods4.1 Each of the methods given requires both a reference anda test sample of traffic paint and a preliminary separation andremoval of the pigm
17、ent component in each.4.2 Method A involves infrared spectral analysis of castfilms of the total vehicle solids to detect spectral differencesbetween the reference and test samples caused by gross orminor adulteration of the test sample.4.3 Method B involves infrared spectral analysis of castfilms o
18、f the unsaponifiable matter that has been separated fromthe vehicle solids in order to detect spectral differencesbetween the reference and test samples caused by lesseradulterations of an unsaponifiable nature and which was notreadily evident when using Method A.4.4 Method C involves gas chromatogr
19、aphic analysis ofprepared methyl esters of the separated fatty acids obtainedfrom the vehicle solids in order to detect chromatographicdifferences between the reference and test samples caused byeither gross or lesser adulteration of the drying oil fraction withextraneous drying oils which may not h
20、ave been readilyevident by the use of Methods A and B.4.5 Method D involves quantitative ultraviolet spectralanalysis of the total vehicle solids dissolved in a nonaromaticspectral grade solvent to give precise concentrations in order todetect ultraviolet spectral absorbance differences between ther
21、eference and test samples caused by minor or sophisticatedadulterations of the vehicle solids and which may not bereadily detected by Method A. Method D is to be used as analternative to Methods B and C.5. Selection of Test Methods and Significance and Use5.1 All of the methods provided involve comp
22、arisons be-tween the spectra or chromatograms of the reference and testsamples to determine if they show significant differences. It isnot possible at this time to establish quantitative limits as aguide to whether a spectral or chromatographic difference istruly significant. Certainly the presence
23、or absence of amoderate or strong peak in the test sample which is not evidentin the reference is significant. A persistent difference in theratios of two peaks of one spectrum as compared to thereference sample is significant. On the whole, some judgmentmust be exercised in this respect and it is a
24、dvisable to refer topublished data on infrared or gas chromatography in order toestablish, where feasible, the possible overall nature of theadulterant or its functional group which might be causing thecomparison spectra to differ.5.2 Method A is rapid and the most convenient of theprocedures given.
25、 It should be utilized first in order to detectnonuniformity of the test sample. Significant spectral differ-ences from that of the reference sample can be taken as anindication of adulteration and in such cases the use of the othermethods is not necessary. As a general rule. Method A issufficient t
26、o detect gross or major adulteration of the vehiclesolids. However, where Method A shows no significant spectraldifferences, it cannot be assumed that the test sample iscompletely acceptable since changes in the type of drying oil,polyol, and certain dibasic acids in alkyd resins, addition ofcertain
27、 aliphatic or nonfunctional hydrocarbon resins, andmany minor adulterations may not always show characteristicinfrared spectral differences. Therefore, in such cases it is bestto proceed to additional tests as given in Methods B and C orelse alternatively directly to Method D.5.3 Method B is useful
28、in detecting adulterations that areunsaponifiable or else have an unsaponifiable component thathas escaped detection in Method A only because the adulterantmay have been small in amount and therefore its strongspectral peaks may have been masked over by the rest of thevehicle solids. Some care shoul
29、d be taken in interpretingspectral differences in Method B to avoid an erroneousconclusion that the test sample is unacceptable because itsspectrum is different. Apparent but unreal differences can occuras a result of incomplete saponification, failure to remove allsaponifiable material, and varying
30、 degrees of contamination ofthe unsaponifiable fraction with sterols, etc., present in thevehicle solids. After it has thus been firmly established that areal spectral difference does exist, further tests are unnecessary,except that it is wise to resort again to the published literatureon infrared t
31、o attempt to identify the possible nature of theadulterant. Where Methods A and B indicate acceptability ofthe test sample, it is still not always possible to rule outadulteration caused by changes or modifications in the saponi-fiable portion, that is, the type of fatty acid, dibasic acids, andpoly
32、ol. In such cases, it is best to continue on to Method C fordetermination of the oil acids, and to other gas chromato-graphic methods for the polyol and dibasic acids when suchequipment is available.5.4 Method C is extremely sensitive in detecting adultera-tions and changes that have been made in th
33、e oil or fatty acidportion of the vehicle solids. It can, for example, detectwhether linseed, coconut, oiticica, etc., has been substituted forsoya oil and vice versa, or whether fish or tall oil has partiallyor wholly replaced some other drying oil, etc. Consequently,when the results of Methods A a
34、nd B suggest that the testsample is acceptable and where a drying oil component isknown to be present, Method C should be used additionally formore complete assurance of product uniformity. Where theresults from Method C along with those from Methods A andB indicate product uniformity, it is a fairl
35、y safe assumption thatthe product has not been significantly altered.5.5 Method D is intended as an alternative to Methods Band C and where the results from Method A indicate apparentproduct acceptability. Method D, by the use of quantitativeultraviolet spectral absorbance data, is an extremely sens
36、itiveprocedure for the detection of complete or even partial adul-teration of the test sample. However, considerable caution mustbe exercised in the preliminary pre-drying of the vehicle solidssince it is at this stage that the components are extremelysensitive to oxidative changes. Even minor oxida
37、tive changescan seriously affect the absorbance data obtained in ultravioletspectral analysis and may give an impression that the twosamples being compared are different when in fact they are thesame. When these considerations are provided for, and thecomparison spectra are identical in Method D as
38、well as inMethod A, then it can be assumed that the sample is acceptable.Significant differences in the spectra from Method D wouldD 2743 68 (2004)2indicate nonuniformity of the product even though Method Amay fail to reveal such nonuniformity.6. Reference Sample6.1 The reference sample of traffic p
39、aint should be at least250 mL and should be truly representative of the initial paintfound acceptable in pre-qualification laboratory or field servicetests, or both, and which paint is subsequently specified forpurchase.6.2 In cases where paint is purchased on the basis offormulation specifications
40、and it is desired to utilize theseprocedures to detect adulteration in delivered lots of paint,reference samples may be synthetically prepared to representthe extremes of the range that will be permitted in theformulation.7. Test Sample7.1 The test samples of the traffic paint should be at least250
41、mL and should be representative of each delivered lot ofpaint that was specified for purchase and which is intended tobe the same as the initial reference paint used in the pre-qualifications acceptance tests from which a reference samplewas retained.8. Sampling Reference and Test Samples8.1 Test an
42、d reference samples of the traffic paint should beobtained in accordance with Practice E 105.9. Preparation of Samples9.1 Separate the vehicle from the pigment by centrifugingthe paint in accordance with Practice D 2372. Transfer andpreserve the vehicle in a well-stoppered amber bottle.METHOD AINFRA
43、RED SPECTRAL ANALYSIS OFTOTAL VEHICLE SOLIDS10. Apparatus10.1 Infrared Spectrophotometer, recording double-beam,and accessory equipment as described in Test Method D 2621.11. Procedure11.1 Obtain the infrared spectra of a cast film of the vehiclesolids of both the test and reference samples by utili
44、zing theprocedure referred to in 10.1. In all cases, however, the spectralintensity of both samples should be well matched (by adjustingthe film thickness) to within 5 % transmission of each other atthe strongest peak, and the transmission of this peak shall bebetween 5 and 15 %. It is also desirabl
45、e to obtain additionalspectra on thicker films or else ordinate scale expansion ifavailable, to bring out spectral differences in the weak tomoderate peak areas. Here again, the same degree of careshould be taken as above to match the film thickness andthereby the overall spectral intensities of the
46、 two samples. Ifdesired, an aid in comparison is to run the test sample againstthe reference sample in the reference beam in order to showsignificant differences by means of a single differential spec-trum. Considerable caution is required in the use and interpre-tation of differential spectra as we
47、ll as proper adjustments ofgain, speed, and slit programs.12. Interpretation of Results12.1 Compare the companion spectra from the test andreference samples for identity by visual inspection preferablyover a light box. Note particularly the presence of an extrane-ous peak or peaks in one which is (a
48、re) not in the other. Alsonote the ratio of intensities of two adjacent or pairs of peaks onone spectra and determine whether this ratio is similar on thecomparison spectra. Any significant difference should be con-sidered as an indication of lack of uniformity between thereference and test samples.
49、 Attempt to ascribe this difference tosome extraneous component or formulation difference betweenthe comparison samples by referring to available infraredliterature and published spectra. Where it is evident that thecomparison spectra are significantly different, no further testsare necessary. When the spectra are identical, proceed toMethods B and C or alternatively to Method D for a fullerevaluation of possible minor or more sophisticated adultera-tion.METHOD BINFRARED SPECTRAL ANALYSIS OFUNSAPONIFIABLE MATTER FROM VEHICLESOLIDS13. Apparatus13.1 Same as in 10.1.14. Procedure1
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