ASTM D4735 – Standard Test Method for Determination of Trace Thiophene in Refined Benzene by Gas Chromatography
Description:
Significance and Use
5.1 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.
5.2 This test method was found applicable for determining thiophene in refined benzene conforming to the specifications described in Specification D2359 and may be applicable toward other grades of benzene if the user has taken the necessary precautions as described in the text.
Scope
1.1 This test method covers the determination of thiophene in refined benzene.
1.2 This test method is applicable to samples with thiophene concentrations in the range from 0.80 mg/kg to 1.80 mg/kg for the Flame Photometric Detector (FPD), and from 0.14 mg/kg to 2.61 mg/kg for the Pulsed Flame Photometric Detector (PFPD). For the PFPD, the minimum level of quantitation (LOQ) is 0.14 mg/kg and the minimum level of detection (LOD) is 0.04 mg/kg. With careful analytical technique, and/or replicates, this method can be used to successfully analyze concentrations below the current LOD. The range of the test method may be extended by modifying the sample injection volume, split ratios, calibration range, or sample dilution with thiophene-free solvent.
Note 1: See Appendix X1 for additional information on calculation of LOD.
Note 2: LOD and LOQ were calculated using data from ASTM Research Report RR:D16-1038.2
1.3 This test method has been found applicable to benzene characteristic of the type described in Specifications D2359 and D4734 and may be applicable to other types or grades of benzene only after the user has demonstrated that the procedure can completely resolve thiophene from the other organic contaminants contained in the sample.
1.4 The following applies for the purposes of determining the conformance to applicable specifications using this test method, results shall be rounded off in accordance the rounding-off method of Practice E29.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
ASTM D473