1、Designation: D5974 00 (Reapproved 2010)D5974 15Standard 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 ad
2、option 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 These test methods cover the determination of the amounts of the indiv
3、idual fatty acids and rosin acids in fractionated talloil products, using capillary gas chromatographic separation of the volatile methyl esters of these acids.1.2 Four methods for forming the methyl esters, and two methods for determining the amounts of the individual fatty acids androsin acids are
4、 described.1.2.1 The classic method for the formation of methyl esters is through the use of diazomethane, but diazomethane is a hazardousand toxic material, and so is no longer the preferred reagent. The use of diazomethane is detailed in the Appendix. Methyl estersmay be formed through the use of
5、tetramethylammonium hydroxide (TMAH), trimethylphenylammonium hydroxide (TMPAH),or N,N-dimethylformamide dimethyl acetal (DMF-DMA).1.2.2 The two methods for determining the amount of the individual fatty acids and rosin acids are the “internal standard”method, which yields absolute values, and the “
6、area percent” method, which yields relative values.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of r
7、egulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D509 Test Methods of Sampling and Grading RosinD804 Terminology Relating to Pine Chemicals, Including Tall Oil and Related ProductsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test M
8、ethod3. Significance and Use3.1 Tall oil fractionated products derived from tall oil are important commercial materials, primarily composed of fatty acidsand rosin acids, but also containing some neutral material (see Terminology D804). For many applications, it is necessary to knowthe level of the
9、individual fatty acids and rosin acids present in these products. Gas chromatography has proven to be a useful toolfor such determinations (see Test Methods D509), and capillary chromatography, described in these test methods, is considered tobe the most effective gas chromatographic technique curre
10、ntly available. In particular situations, other techniques may be moresuitable than gas chromatography. For example, the presence of fatty acid esters in the sample would result in transesterificationduring the derivatization step that may affect the results.3.2 Due to hydrogen bonding, unmodified t
11、all oil fatty acids and rosin acids cannot be volatilized at atmospheric pressurewithout undergoing decomposition. So, it is necessary to convert the free acids to the more volatile and more stable methyl esters,prior to chromatographic separation.3.3 These test methods describe four ways to prepare
12、 methyl esters. The classic method is through the use of diazomethane, butdiazomethane is a hazardous and toxic material, and so is no longer the preferred agent. The use of diazomethane is detailed inAppendix X1the Appendix1 These test methods are under the jurisdiction of ASTM Committee D01 on Pai
13、nt and Related Coatings, Materials, and Applications and are the direct responsibility ofSubcommittee D01.34 on Pine Chemicals and Hydrocarbon Resins.Current edition approved June 1, 2010July 1, 2015. Published June 2010August 2015. Originally approved in 1996. Last previous edition approved in 2005
14、2010 asD5974 00 (2005).(2010). DOI: 10.1520/D5974-00R10.10.1520/D5974-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standardsstandards Document Summary page
15、 on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that us
16、ers consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.3.1 TMAH causes isomeriza
17、tion of a samplessamples di- and polyunsaturated fatty acids, when it is used in even a slightexcess. This leads to inaccurate results for the individual fatty acid components. TMAH should be used for materials containingonly rosin acids, or when the identification or quantitation of individual fatt
18、y acid components is not important.3.3.2 TMPAH is the recommended methylating agent when the identification or quantitation of individual di- andpolyunsaturated fatty acids is required. TMPAH produces results that are very similar to those of diazomethane, but without thehazards that are associated
19、with diazomethane. A considerable excess of TMPAH may cause isomerization of conjugatedcompounds similar to that encountered with TMAH.3.3.3 DMF-DMA gives results comparable to TMPAH and is easy and safe to use. However, the reagent is moisture sensitive,requiring samples to be free of any significa
20、nt levels of water.3.4 Two test methods for calculating the amounts of the individual fatty acid and rosin acid methyl esters are included in thesetest methods. When the actual weight percentage of a given compound is required, the “internal standard” method must be used.This method involves adding
21、a known amount of an internal standard to a known amount of test material, and comparing the areaof the peak associated with the internal standard with the area of the peak of the individual fatty acid or rosin acid methyl esters.The “area percent” method will give the relative amount of each compon
22、ent, by comparing the area of the appropriate peak to thetotal 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 being dependent on the factors mentioned in 3.3
23、.4. Conversion By Means of Tetramethylammonium Hydroxide (TMAH)4.1 Apparatus:4.1.1 Standard Laboratory Equipment.4.2 Reagents and Materials:4.2.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents shall conform to the spe
24、cifications of the Committee on Analytical Reagents of the American Chemical Society3, wheresuch specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently highpurity to permit its use without lessening the accuracy of the determinati
25、on.4.2.2 Tetramethylammonium Hydroxide Solution, 24 % in methanol, CAS No. 75-59-2.4.2.3 Tetramethylammonium Hydroxide Solution, 6 % (v/v) in methanol. Dilute 25 mL of the reagent described in 4.2.2 with75 mL of methanol.4.2.4 Phenolphthalein Solution, 1 % (w/v) in methanol.4.2.5 Diethyl Ether, anhy
26、drous.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 3.0 mL of a 50:50 ether/methanol mixture, add 2 to 3 drops ofphenolphthalein indicator solution, and titrate to a pH of
27、7.8 to 8.1 or to the very first permanent pink color, with the 6 % solutionof TMAH. If the solution is overtitrated, it can be back titrated with the acetic acid in methanol solution to the end point. Whenthe solution is injected into the heated injection port of the chromatograph, the tetramethylam
28、monium salts are pyrolyzed to methylesters.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 of TMAH,to assist in dissolving the sample.5. Conversion By Means of Trimethylphenylammonium Hydroxide (TMPAH)5.1
29、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 M or 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, optional.3 Reagent Chem
30、icals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and Nati
31、onalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D5974 1525.3 Procedure:5.3.1 Add 0.5 to 3.0 mL of a 50:50 ether/methanol, to the sample from 9.2.2 or 17.1. Add 2 to 3 drops of phenolphthaleinindicator solution and titrate to the very first permanent pink color with the TMPAH
32、 in methanol solution. When the solution isinjected into the heated injection port of the chromatograph, the trimethylphenylammonium salts are pyrolyzed to their respectivemethyl esters.NOTE 3For solid rosin, or other samples that are difficult to dissolve, 2 to 3 drops of toluene may be added to th
33、e vial prior to the addition of TMPAH,to assist in dissolving the sample.6. Conversion by Means of N,N-Dimethylformamide Dimethyl 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 acet
34、al (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 9.2.2 or 17.1 in an appropriate anhydrous vial, and dissolve with approximately 0.5 mL of eithermethanol or toluene. Add approximately 1 mL of DMF-DMA, mix well, and maintain the sample
35、at 3040C for 15 minutes.INTERNAL STANDARD METHOD7. Apparatus7.1 Gas ChromatographAn instrument equipped with a flame ionization detector (FID) that can be operated at conditionsgiven in 10.1.7.2 ColumnA high resolution column between 15 and 60 m and 60 m in length, 0.25up to 0.53 mm internal diamete
36、r, witha 0.20-m film thickness of biscyanopropylsiloxane type liquid phase. The recommended referee column is 30 m in length, 0.32mm internal diameter, with a 0.20-m film thickness, and provides separations equivalent or better than that displayed in Fig. 1.NOTE 4When using this method for referee p
37、urposes, verify that the resolution is adequate and comparable to that shown in Fig. 1.7.3 Analytical Balance, accurate to 0.1 mg.NOTE 1Labeled peaks are eluted as methyl esters.FIG. 1 Typical Chromatogram of Distilled Tall OilD5974 1538. Reagents and Materials8.1 Purity of Reagents, see 4.2.1.8.2 M
38、yristic Acid (Internal Standard),99 % pure.NOTE 5A higher molecular-weight saturated fatty acid that elutes as a methyl ester later in the chromatogram may be used in place of, or in additionto myristic acid, provided that the alternative internal standard peak does not coelute with sample component
39、 peaks.8.3 Stearic Acid, Oleic Acid, Linoleic Acid, Abietic Acid, and Dehydroabietic AcidOther high purity reference standards canbe added as needed.9. Procedure9.1 Preparation of Calibration Standard:9.1.1 Accurately weigh into a suitable vial, milligram quantities of the myristic acid internal sta
40、ndard, plus the fatty acid androsin acid standards that are anticipated to be in the test sample, and record the weights.9.1.2 Convert the calibration standard to the methyl esters or substituted ammonium salts as described in Sections 4, 5, 6.9.2 Preparation of Test Sample:9.2.1 Accurately weigh ;5
41、0 mg of sample and ;15 mg of myristic acid directly into a suitable vial and record the weight.D5974 154NOTE 6Rosin samples need to be freshly broken from a larger mass to ensure the results are not affected by air oxidation of the rosin.9.2.2 Convert the test sample to methyl esters or substituted
42、ammonium 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 7) as follows:Column temperature (oven temperature)Initial 150CHold 5 minRamp 5C/minFinal 250CHold 10 minInjection port temperature 300CInjection p
43、ort liner glass splitDetector temperature 325CCarrier gas heliumLinear gas velocity 19.520.5 cm/sSplit ratio 100 to 1 maximumDetector FIDHydrogen 30 mL/minAir 400 mL/minMakeup gas 30 mL/minNOTE 7These are typical operating conditions only. The individual instrument should be adjusted in accordance w
44、ith manufacturers instructions tooptimize desired performance. Ongoing adjustments in operating temperature and flow rate may be necessary to maintain optimum performance of thecolumn due to aging.10.2 Calibration:10.2.1 Inject 0.5 to 1.0 L of the appropriate standard prepared in 9.1.10.2.2 Record t
45、he retention time and calculate the individual relative response factors as follows:RRFi 5WiAi3AISWIS(1)where:RRFI = relative response factor of individual fatty or rosin acid methyl esters,WI = weight of individual fatty or rosin acid methyl esters in standard, Wi = weight used purity,AI = peak are
46、a of individual fatty or rosin acid,AIS = peak area of internal standard, andWIS = weight of internal standard. WIS = weight used purity.NOTE 8For highest accuracy, the purity of the standards should be used to correct the weight terms.11. Analysis11.1 Inject 0.5 to 1.0 L of the test sample prepared
47、 in 9.2.2.NOTE 9Dilution of the sample with additional solvent may be necessary to obtain injections that do not overload the column or detector.12. Calculation12.1 Obtain the peak areas of all of the peaks needed from the chromatogram.NOTE 10See Fig. 1 for chromatogram of a typical distilled tall o
48、il (DTO).12.2 Calculate the absolute value of each peak of interest, as follows:TABLE 1 Precision of Internal Standard MethodRepeatabilityLimit, 95 %RepeatabilityStandard DeviationReproducibilityLimit, 95 %ReproducibilityStandard DeviationTOFA MaterialStearic acid 0.6 0.2 0.8 0.3Oleic acid 7.6 2.7 1
49、0.4 3.7Linoleic acid 5.0 1.8 7.3 2.6DTO MaterialStearic acid 0.2 0.09 0.6 0.2Oleic acid 1.4 0.5 1.7 0.6Linoleic acid 1.1 0.4 1.4 0.5Abietic acid 0.6 0.2 0.8 0.3Dehydroabietic acid 0.3 0.1 0.8 0.3ROSIN MaterialAbietic acid 6.4 2.3 10.6 3.8Dehydroabietic acid 2.0 0.7 2.8 1.0D5974 155Fatty or rosin acid,%5Ai 3RRFi 3WISAIS 3WS3100 (2)where:AI = peak area for fatty or resin acid methyl ester being determined,RRFI = relative response factor for individual compound being determined,WIS = weight of internal standard. WIS = weight used times purity,
