1、Designation: D 5974 00 (Reapproved 2005)Standard Test Methods forFatty and Rosin Acids in Tall Oil Fractionation Products byCapillary Gas Chromatography1This standard is issued under the fixed designation D 5974; the number immediately following the designation indicates the year oforiginal adoption
2、 or, in the 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 test methods cover the determination of theamounts of the individual
3、fatty 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 descr
4、ibed.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 tetramet
5、hy-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 perc
6、ent”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
7、 limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 509 Test Methods of Sampling and Grading RosinD 804 Terminology Relating to Naval Stores, Including TallOil and Related ProductsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. S
8、ignificance 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 D 804). For many applications, it is neces-sary to know the level of the individu
9、al fatty acids and rosinacids present in these products. Gas chromatography hasproven to be a useful tool for such determinations (see TestMethods D 509), and capillary chromatography, described inthese test methods, is considered to be the most effective gaschromatographic technique currently avail
10、able. In particularsituations, other techniques may be more suitable than gaschromatography. For example, the presence of fatty acid estersin the sample would result in transesterification during thederivatization step that may affect the results.3.2 Due to hydrogen bonding, unmodified tall oil fatt
11、y acidsand 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.
12、 The 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 ev
13、en a 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
14、 whenthe 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 thehazards that are associated with diazomethane. A considerableexcess of TMPAH may cause isomerization of conjuga
15、tedcompounds similar to that encountered with TMAH.1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coatings, Materials, and Applications and are the directresponsibility of Subcommittee D01.34 on Naval Stores.Current edition approved Dec. 1, 2005. Published F
16、ebruary 2006. Originallyapproved in 1996. Last previous edition approved in 2000 as D 5974 00.2For 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
17、 Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.3.3 DMF-DMA gives results comparable to TMPAH andis easy and safe to use. However, the reagent is moisturesensitive, requiring samples to be free of a
18、ny 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 standard” methodmust be used. This method involve
19、s 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 percent” method willgive the relative amount of each
20、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 choice beingdependent on the factors mentioned in
21、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 intended thatall reagents shall conform to the sp
22、ecifications 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 without lessening theaccuracy of the determination
23、.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/v) in methanol.4.2.5 Diethyl Ether, anhydrous.4
24、.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 indicator solution, and titrate to a pH of 7.8 to8.
25、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 the chromatograph, the tetramethylammonium salt
26、s 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 TrimethylphenylammoniumHydroxide (TMPAH)5.1 Apparatus:5.1
27、.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 Toluene, optional5.3 Procedure:5.3.1 Add 0.5 t
28、o 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 injection port of thechromatograph, the trimet
29、hylphenylammonium 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 sample.6. Conversion by Means of N,N-Dimethylfor
30、mamideDimethyl 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 Toluene.6.3 Procedure:6.3.1 Place the sample from 9
31、.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 ChromatographAn instrument equipped with aflame io
32、nization 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.The recommended referee column is 30 m in length, 0.32
33、 mminternal diameter, with a 0.20-m film thickness, and providesseparations equivalent or better than that displayed in Fig. 1.3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American
34、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.D 5974 00 (2005)2NOTE 4When using this method for referee purposes, verify that theresolut
35、ion 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 acid that elutes asa methyl ester later in the
36、 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 high purity reference stan-dards can be added
37、 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 testsample, and record the weights.9.1.2 Convert the
38、 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.NOTE 6Rosin samples need to be freshly broken
39、 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 conditions so that they are approximately(see Note
40、 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 ratio 100 to 1 maximumDetector FIDHydrogen 30 mL/
41、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 operatingtemperature and flow rate may be necessary to maintain o
42、ptimumperformance 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:NOTE 1Labeled peaks are eluted as methyl esters.FIG. 1 Typical Chrom
43、atogram of Distilled Tall OilD 5974 00 (2005)3RRFi5WiAi3AISWIS(1)where: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 area of individual fatty or rosin acid,AIS= pe
44、ak 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 in 9.2.2.NOTE 9Dilution of the sample with ad
45、ditional 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(DTO).12.2 Calculate the absolute value of eac
46、h 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 standard. WIS= weight usedtimes purity,AIS= peak
47、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 of fatty and rosin acids in talloil fatty acid
48、s (TOFA), DTO, and rosin was run in 1995 by ninelaboratories. The design of the experiment, similar to that ofPractice E 691, and a within-between analysis of the data aregiven in ASTM Research Report.414.1.1 Test ResultThe precision information given inTable 1 for fatty and rosin acids is for the c
49、omparison 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 SampleWeigh approximately 50mg of sample into a
