ASTM D5917 Test Method for Trace Impurities in Monocyclic Aromatic Hydrocarbons
ASTM D5917 Standard Test Method for Trace Impurities in Monocyclic Aromatic Hydrocarbons by Gas Chromatography and External Calibration
15. Report
15.1 Report individual impurities, total nonaromatics, and total C9 aromatics, to the nearest 0.001 %.
15.2 For concentrations of impurities less than 0.001 %, report as <0.001 %, and consider as 0.000 in summation of impurities.
15.3 Report the total impurities to the nearest 0.01 %.
15.4 Report purity as "purity (by GC)" to the nearest 0.01 %.
15.5 Report mixed xylenes to the nearest 0.01 %.
16. Precision and Bias
16.1 Precision - The following criteria should be used to judge the acceptability of results obtained by this test method (95 % confidence level). The precision criteria for toluene and mixed xylenes were derived from an interlaboratory study using data submitted by six laboratories. Each round-robin participant was provided with two calibration standards, a sample of mixed xylenes and a sample of toluene. Each sample was run twice in two days by two different operators. The precision criteria for p -xylene were derived from one laboratory analyzing the same sample once a day for a period of 51 days. Results of the interlaboratory study were calculated and analyzed using Practice E691. Since the p-xylene data are from only one laboratory, no Reproducibility is listed.
16.1.1 The numbers in parentheses shown in the left hand column of Table 3 are reported average concentrations of the impurities.
16.2 Intermediate Precision - Duplicate results by the same operator should not be considered suspect unless they differ by more than 6 the amount shown in Table 3. All values are in weight %.
16.3 Reproducibility - The results between two laboratories should not be considered suspect unless they differ by more than 6 the amount shown in Table 3. All values are in weight %.
16.4 Bias - Since there was no accepted reference material available at the time of interlaboratory testing, no statement on bias can be made at this time.
17. Quality Guidelines
17.1 Refer to Guide D6809 for suggested QA/QC activities that can be used as part of this method. It is recommended that the operator of this method select and perform relevant QA/QC activities like the ones in Guide D6809 to help ensure the quality of the data generated by this method.
18. Keywords
18.1 aromatics; external standard; gas chromatography; impurities; purity; p-xylene; toluene; xylenes
