1、Designation: D7716 11aStandard Test Method forDetermination of Residual Methanol in Glycerin by GasChromatography1This standard is issued under the fixed designation D7716; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f 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 provides for the quantitative determi-nation of residual methanol in glycerin by gas chromatography
3、.The range of detection for residual methanol is 0.02 to 0.60mass %.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It
4、 is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD7640 Specification for Engine Coolant Grad
5、e GlycerinE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE355 Practice for Gas Chromatography Terms and Rela-tionshipsE594 Practice for Testing Flame Ionization Detectors Usedin Gas or Supercritical Fluid ChromatographyE691 Practice for Conducting an Interlaboratory Study t
6、oDetermine the Precision of a Test Method3. Terminology3.1 DefinitionsThis test method makes reference to manycommon gas chromatographic procedures, terms, and relation-ships. Detailed definitions can be found in Practices E355 andE594.4. Summary of Test Method4.1 The sample is analyzed by headspace
7、 gas chromatogra-phy. Calibration is achieved by the use of external standards ofmethanol in water.5. Significance and Use5.1 Methanol content reflects the quality of glycerin for useas an engine coolant. The current specification for the maxi-mum methanol content is 0.1 % weight to weight (w/w).6.
8、Apparatus6.1 Chromatographic SystemSee Practice E355 for spe-cific designations and definitions. The gas chromatograph (GC)system shall be capable of operating at the conditions given inTable 1.6.2 Autosampler system, Gerstel multipurpose samplerMPS-23or equivalent. This method can also be run manua
9、lly.6.3 Column, open tubular column with polyethylene glycol(PEG) bonded and cross-linked phase internal coating. Thecolumn should have an upper temperature limit of 260C. Acolumn 30 m in length, with an internal diameter of 0.32 mm,and a 1.0-m film thickness has been found satisfactory. Anycolumn w
10、ith equivalent or better chromatographic efficiencyand selectivity can be used.6.4 Electronic Data Acquisition SystemA computer ca-pable of providing real-time graphic and digital presentation ofthe chromatographic data is recommended for use. Peak areasand retention times shall be measured by compu
11、ter or elec-tronic integration (integrator).7. Reagents and Materials7.1 Purity of ReagentsReagent-grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Soci
12、ety where1This test method is under the jurisdiction of ASTM Committee D15 on EngineCoolants and Related Fluids and is the direct responsibility of SubcommitteeD15.93 on Research and Long Range Planning.Current edition approved Oct. 1, 2011. Published November 2011. Originallyapproved in 2011. Last
13、previous edition approved in 2011 as D7716 11. DOI:10.1520/D7716-11A.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 page onthe ASTM
14、website.3The sole source of supply of the apparatus known to the committee at this timeis GERSTEL GmbH the details are given in RR:D15-1029.612.1.1 Repeatability Limit, rTwo test results obtainedwithin one laboratory shall be judged not equivalent if theydiffer by more than the r value for that mate
15、rial; r is the intervalrepresenting the critical difference between two test results forthe same material, obtained by the same operator using thesame equipment on the same day in the same laboratory.12.1.1.1 Repeatability limits are listed in Table 2.12.1.2 Reproducibility Limit, RTwo test results
16、shall bejudged not equivalent if they differ by more than the R valuefor that material; R is the interval representing the criticaldifference between two test results for the same material,obtained by different operators using different equipment indifferent laboratories.12.1.2.1 Reproducibility lim
17、its are listed in Table 2.12.1.3 The above terms (repeatability limit and reproduc-ibility limit) are used as specified in Practice E177.12.1.4 Any judgment made in accordance with statements12.1.1 and 12.1.2 would have an approximate 95 % probabilityof being correct.12.2 BiasAs there were no certif
18、ied reference materialstested as part of this study, no statement on bias is being made.12.3 The precision statement was determined through sta-tistical examination of 40 test results, submitted by sevenlaboratories, measuring residual methanol in three glycerinsamples.12.3.1 The three materials wer
19、e described as follows:Material 1 99.5% glycerin, no spikeMaterial 2 99.5% glycerin, spiked with805 ppm methanolMaterial 3 99.5% glycerin, spiked with1097 ppm methanol12.4 To judge the equivalency of two test results, it isrecommended to choose the material that is closest in charac-teristics to the
20、 test material.13. Keywords13.1 gas chromatography; glycerin; headspace; methanolASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the va
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25、/COPYRIGHT/).6Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D15-1029.TABLE 2 Residual Methanol (ppm)MaterialNumber ofData SetsContributingto PrecisionCalculationsAverage, xRepeatabilityStandardDeviation, srReproducibilityStandardDeviation, sRRepeatabilityLimit, rReproducibilityLimit, R5441.72-A 7 0.0 0.0 0.0 0.0 0.05441.72-B 7 734.7 20.6 99.0 57.6 277.15441.72-C 6 1146.3 64.8 145.2 181.5 406.7D7716 11a4
