【国外标准】 Standard Test Method for Traces of Thiophene in Benzene by Spectrophotometry (Withdrawn 2009)

This test method is suitable for setting specifications on benzene and for use as an internal quality control tool where benzene is either produced or used in a manufacturing process. It may also be used in development or research work involving benzene.1.1 This test method covers the determination of thiophene in benzene in which the thiophene concentration is between 0.1 and 250 mg/kg.1.2 Contaminating materials that are darkened by sulfuric acid interfere and must be compensated for by a sample blank determination. Neither carbon disulfide in concentrations as high as 100 mg/kg nor water as high as the level of saturation will interfere.1.3 Contaminating materials may occasionally cause the color development in this test method to be time dependent and may also contribute to spectral interferences at 589 nm. Consequently, test results indicating substantial thiophene, that cannot be verified by total sulfur analysis, should be considered suspect.1.4 In determining the conformance of the test results using this method to applicable specifications, results shall be rounded off in accordance with the rounding-off method of Practice E 29.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see 7.6, 8.1, and 9.1.