1、Designation: D5974 00 (Reapproved 2010)Standard Test Methods forFatty and Rosin Acids in Tall Oil Fractionation Products byCapillary Gas Chromatography1This standard is issued under the fixed designation D5974; the number immediately following the designation indicates the year oforiginal adoption o
2、r, 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 These test methods cover the determination of theamounts of the individual fat
3、ty acids and rosin acids infractionated tall oil products, using capillary gas chromato-graphic separation of the volatile methyl esters of these acids.1.2 Four methods for forming the methyl esters, and twomethods for determining the amounts of the individual fattyacids and rosin acids are describe
4、d.1.2.1 The classic method for the formation of methyl estersis through the use of diazomethane, but diazomethane is ahazardous and toxic material, and so is no longer the preferredreagent. The use of diazomethane is detailed in the Appendix.Methyl esters may be formed through the use of tetramethy-
5、lammonium hydroxide (TMAH), trimethylphenylammoniumhydroxide (TMPAH), or N,N-dimethylformamide dimethylacetal (DMF-DMA).1.2.2 The two methods for determining the amount of theindividual fatty acids and rosin acids are the “internal standard”method, which yields absolute values, and the “area percent
6、”method, which yields relative values.1.3 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 li
7、mitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D509 Test Methods of Sampling and Grading RosinD804 Terminology Relating to Naval Stores, Including TallOil and Related ProductsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Signifi
8、cance and Use3.1 Tall oil fractionated products derived from tall oil areimportant commercial materials, primarily composed of fattyacids and rosin acids, but also containing some neutral material(see Terminology D804). For many applications, it is necessaryto know the level of the individual fatty
9、acids and rosin acidspresent in these products. Gas chromatography has proven tobe a useful tool for such determinations (see Test MethodsD509), and capillary chromatography, described in these testmethods, is considered to be the most effective gas chromato-graphic technique currently available. In
10、 particular situations,other techniques may be more suitable than gas chromatogra-phy. For example, the presence of fatty acid esters in thesample would result in transesterification during the derivati-zation step that may affect the results.3.2 Due to hydrogen bonding, unmodified tall oil fatty ac
11、idsand rosin acids cannot be volatilized at atmospheric pressurewithout undergoing decomposition. So, it is necessary toconvert the free acids to the more volatile and more stablemethyl esters, prior to chromatographic separation.3.3 These test methods describe four ways to preparemethyl esters. The
12、 classic method is through the use ofdiazomethane, but diazomethane is a hazardous and toxicmaterial, and so is no longer the preferred agent. The use ofdiazomethane is detailed in the Appendix.3.3.1 TMAH causes isomerization of a samples di- andpolyunsaturated fatty acids, when it is used in even a
13、 slightexcess. This leads to inaccurate results for the individual fattyacid components. TMAH should be used for materials contain-ing only rosin acids, or when the identification or quantitationof individual fatty acid components is not important.3.3.2 TMPAH is the recommended methylating agent whe
14、nthe identification or quantitation of individual di- and polyun-saturated fatty acids is required. TMPAH produces results thatare very similar to those of diazomethane, but without the1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coatings, Materials, and A
15、pplications and are the directresponsibility of Subcommittee D01.34 on Pine Chemicals and HydrocarbonResins.Current edition approved June 1, 2010. Published June 2010. Originallyapproved in 1996. Last previous edition approved in 2005 as D5974 00 (2005).DOI: 10.1520/D5974-00R10.2For referenced ASTM
16、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 page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohock
17、en, PA 19428-2959, United States.hazards that are associated with diazomethane. A considerableexcess of TMPAH may cause isomerization of conjugatedcompounds similar to that encountered with TMAH.3.3.3 DMF-DMA gives results comparable to TMPAH andis easy and safe to use. However, the reagent is moist
18、uresensitive, requiring samples to be free of any significant levelsof water.3.4 Two test methods for calculating the amounts of theindividual fatty acid and rosin acid methyl esters are includedin these test methods. When the actual weight percentage of agiven compound is required, the “internal st
19、andard” methodmust be used. This method involves adding a known amount ofan internal standard to a known amount of test material, andcomparing the area of the peak associated with the internalstandard with the area of the peak of the individual fatty acidor rosin acid methyl esters. The “area percen
20、t” method willgive the relative amount of each component, by comparing thearea of the appropriate peak to the total area of all peaks.Non-eluting compounds will lead to erroneous (absolute)results with this method.PREPARATION OF METHYL ESTERSNOTE 1Any of these three methods can be used, with the cho
21、ice beingdependent on the factors mentioned in 3.3.4. Conversion By Means of TetramethylammoniumHydroxide (TMAH)4.1 Apparatus:4.1.1 Standard Laboratory Equipment.4.2 Reagents and Materials:4.2.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is in
22、tended thatall reagents shall conform to the specifications of the Commit-tee onAnalytical Reagents of theAmerican Chemical Society3,where such specifications are available. Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use wit
23、hout lessening theaccuracy of the determination.4.2.2 Tetramethylammonium Hydroxide Solution,24%inmethanol, CAS No. 75-59-2.4.2.3 Tetramethylammonium Hydroxide Solution, 6 % (v/v)in methanol. Dilute 25 mL of the reagent described in 4.2.2with 75 mL of methanol.4.2.4 Phenolphthalein Solution, 1 % (w/
24、v) in methanol.4.2.5 Diethyl Ether, anhydrous.4.2.6 Methanol, anhydrous.4.2.7 Acetic Acid, 5 % volume/volume (v/v) in methanol.4.2.8 Toluene, optional.4.3 Procedure:4.3.1 Dissolve the sample from 9.2.2 or 17.1 in 0.5 to 3.0mL of a 50:50 ether/methanol mixture, add 2 to 3 drops ofphenolphthalein indi
25、cator solution, and titrate to a pH of 7.8 to8.1 or to the very first permanent pink color, with the 6 %solution of TMAH. If the solution is overtitrated, it can be backtitrated with the acetic acid in methanol solution to the endpoint. When the solution is injected into the heated injectionport of
26、the chromatograph, the tetramethylammonium salts arepyrolyzed to methyl esters.NOTE 2For solid rosin, or other samples that are difficult to dissolve,2 to 3 drops of toluene may be added to the vial prior to the addition ofTMAH, to assist in dissolving the sample.5. Conversion By Means of Trimethylp
27、henylammoniumHydroxide (TMPAH)5.1 Apparatus:5.1.1 Standard Laboratory Equipment.5.2 Reagents and Materials:5.2.1 Purity of Reagents, see 4.2.1.5.2.2 Trimethylphenylammonium Hydroxide Solution, 0.2 Mor 0.1 M in methanol, CAS No. 1899-02-1.5.2.3 Diethyl Ether, anhydrous.5.2.4 Methanol, anhydrous.5.2.5
28、 Toluene, optional5.3 Procedure:5.3.1 Add 0.5 to 3.0 mL of a 50:50 ether/methanol, to thesample from 9.2.2 or 17.1.Add 2 to 3 drops of phenolphthaleinindicator solution and titrate to the very first permanent pinkcolor with the TMPAH in methanol solution. When thesolution is injected into the heated
29、 injection port of thechromatograph, the trimethylphenylammonium salts are pyro-lyzed to their respective methyl esters.NOTE 3For solid rosin, or other samples that are difficult to dissolve,2 to 3 drops of toluene may be added to the vial prior to the addition ofTMPAH, to assist in dissolving the s
30、ample.6. Conversion by Means of N,N-DimethylformamideDimethyl Acetal (DMF-DMA)6.1 Apparatus:6.1.1 Standard Laboratory Equipment.6.2 Reagents and Materials:6.2.1 Purity of Reagents, see 4.2.1.6.2.2 N,N-Dimethylformamide dimethyl acetal (DMF-DMA), CAS No. 4637-24-5.6.2.3 Methanol, anhydrous.6.2.4 Tolu
31、ene.6.3 Procedure:6.3.1 Place the sample from 9.2.2 or 17.1 in an appropriateanhydrous vial, and dissolve with approximately 0.5 mL ofeither methanol or toluene. Add approximately 1 mL ofDMF-DMA, mix well, and maintain the sample at 3040C for15 minutes.INTERNAL STANDARD METHOD7. Apparatus7.1 Gas Chr
32、omatographAn instrument equipped with aflame ionization detector (FID) that can be operated at condi-tions given in 10.1.7.2 ColumnA high resolution column between 15 and 60m in length, 0.25 to 0.53 mm internal diameter, with a 0.20-mfilm thickness of biscyanopropylsiloxane type liquid phase.3Reagen
33、t 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 Pharmacopeiaand N
34、ational Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D5974 00 (2010)2The recommended referee column is 30 m in length, 0.32 mminternal diameter, with a 0.20-m film thickness, and providesseparations equivalent or better than that displayed in Fig. 1.NOTE 4When using this metho
35、d for referee purposes, verify that theresolution is adequate and comparable to that shown in Fig. 1.7.3 Analytical Balance, accurate to 0.1 mg.8. Reagents and Materials8.1 Purity of Reagents, see 4.2.1.8.2 Myristic Acid (Internal Standard), 99 % pure.NOTE 5A higher molecular-weight saturated fatty
36、acid that elutes asa methyl ester later in the chromatogram may be used in place of, or inaddition to myristic acid, provided that the alternative internal standardpeak does not coelute with sample component peaks.8.3 Stearic Acid, Oleic Acid, Linoleic Acid, Abietic Acid,and Dehydroabietic AcidOther
37、 high purity reference stan-dards can be added as needed.9. Procedure9.1 Preparation of Calibration Standard:9.1.1 Accurately weigh into a suitable vial, milligram quan-tities of the myristic acid internal standard, plus the fatty acidand rosin acid standards that are anticipated to be in the testsa
38、mple, and record the weights.9.1.2 Convert the calibration standard to the methyl estersor substituted ammonium salts as described in Sections 4, 5, 6.9.2 Preparation of Test Sample:9.2.1 Accurately weigh ;50 mg of sample and ;15 mg ofmyristic acid directly into a suitable vial and record the weight
39、.NOTE 6Rosin samples need to be freshly broken from a larger massto ensure the results are not affected by air oxidation of the rosin.9.2.2 Convert the test sample to methyl esters or substitutedammonium salts, as described in Sections 4, 5, 6.10. Set-up of Gas Chromatograph (GC)10.1 Set the GC cond
40、itions so that they are approximately(see Note 7) as follows:Column temperature (oven temperature)Initial 150CHold 5 minRamp 5C/minFinal 250CHold 10 minInjection port temperature 300CInjection port liner glass splitDetector temperature 325CCarrier gas heliumLinear gas velocity 19.520.5 cm/sSplit rat
41、io 100 to 1 maximumDetector FIDHydrogen 30 mL/minAir 400 mL/minMakeup gas 30 mL/minNOTE 7These are typical operating conditions only. The individualinstrument should be adjusted in accordance with manufacturers instruc-tions to optimize desired performance. Ongoing adjustments in operatingtemperatur
42、e and flow rate may be necessary to maintain optimumperformance of the column due to aging.10.2 Calibration:10.2.1 Inject 0.5 to 1.0 L of the appropriate standardprepared in 9.1.10.2.2 Record the retention time and calculate the indi-vidual relative response factors as follows:RRFi5WiAi3AISWIS(1)NOT
43、E 1Labeled peaks are eluted as methyl esters.FIG. 1 Typical Chromatogram of Distilled Tall OilD5974 00 (2010)3where:RRFI= relative response factor of individual fatty or rosinacid methyl esters,WI= weight of individual fatty or rosin acid methylesters in standard, Wi= weight used 3 purity,AI= peak a
44、rea of individual fatty or rosin acid,AIS= peak area of internal standard, andWIS= weight of internal standard. WIS= weight used 3purity.NOTE 8For highest accuracy, the purity of the standards should beused to correct the weight terms.11. Analysis11.1 Inject 0.5 to 1.0 L of the test sample prepared
45、in 9.2.2.NOTE 9Dilution of the sample with additional solvent may benecessary to obtain injections that do not overload the column or detector.12. Calculation12.1 Obtain the peak areas of all of the peaks needed fromthe chromatogram.NOTE 10See Fig. 1 for chromatogram of a typical distilled tall oil(
46、DTO).12.2 Calculate the absolute value of each peak of interest, asfollows:Fatty or rosin acid, % 5Ai3 RRFi3 WISAIS3 WS3 100 (2)where:AI= peak area for fatty or resin acid methyl ester beingdetermined,RRFI= relative response factor for individual compoundbeing determined,WIS= weight of internal stan
47、dard. WIS= weight usedtimes purity,AIS= peak area of internal standard, andWS= sample weight.13. Report13.1 Report the percentage of the individual fatty and rosinacids to the nearest 0.1 %.14. Precision and Bias14.1 Internal Standard MethodAn interlaboratory studyof the capillary GC determination o
48、f fatty and rosin acids in talloil fatty acids (TOFA), DTO, and rosin was run in 1995 by ninelaboratories. The design of the experiment, similar to that ofPractice E691, and a within-between analysis of the data aregiven in ASTM Research Report.414.1.1 Test ResultThe precision information given inTa
49、ble 1 for fatty and rosin acids is for the comparison of twotest results.NOTE 11Repeatability = within laboratory, Reproducibility = be-tween laboratories.14.1.2 BiasSince there is no accepted reference material,method or laboratory suitable for determining the bias for theprocedure in this test method for measuring component con-centration, no statement on bias is being made.AREA PERCENT METHOD15. ApparatusSame as apparatus described in Section 7.16. Reagents and Materials16.1 Purity of ReagentsSee 4.2.1.17. Procedure17.1 Preparation of Test Sam
