ASTM D7871-2018 pdf free download
ASTM D7871-2018 pdf free download.Standard Test Method for Analysis of Cyclohexane by Gas Chromatography (Effective Carbon Number)
1. Scope
1.1 This test method covers the determination of the purity of cyclohexane by gas chromatography. 1.2 This test method has been found applicable to the measurement of impurities such as those found in Table 1, which are impurities that may be found in cyclohexane. The impurities can be analyzed over a range of 1 to 400 mg/kg by this method, but may be applicable to a wider range. 1.3 The limit of detection is 1 mg/kg. 1.4 In determining the conformance of the test results using this test method to applicable specifications, results shall be rounded off in accordance with 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. 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 appro- priate safety, health, and environmental practices and deter- mine the applicability of regulatory limitations prior to use. For specific hazards statements, see Section 8. 1.7 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
5. Significance and Use
5.1 This test method is suitable for setting specifications on the materials referenced in Table 1 and for use as an internal quality control tool where cyclohexane is produced or is used in a manufacturing process. It may also be used in development or research work involving cyclohexane. 5.2 This test method is useful in determining the purity of cyclohexane with normal impurities present. If extremely high boiling or unusual impurities are present in the cyclohexane, this test method would not necessarily detect them and the purity calculation would be erroneous.
6. Apparatus
6.1 Gas Chromatograph—Any instrument having a flame ionization detector that can be operated at the conditions given in Table 2. The system should have sufficient sensitivity to obtain a minimum peak height response for 1 mg/kg benzene of twice the height of the signal background noise. 6.2 Columns—The choice of column is based on resolution requirements. Any column may be used that is capable of resolving all significant impurities from cyclohexane. The column described in Table 2 has been used successfully. 6.3 Recorder—Electronic integration is required. 6.4 Injector—The specimen must be precisely and repeat- ably injected into the gas chromatograph. An automatic sample injection device is highly recommended. Manual injection may be employed if the precision stated in Tables 4–8 can be reliably and consistently satisfied.
7. Reagents and Materials
7.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Commit- tee on Analytical Reagents of the American Chemical Society, where such specifications are available. 5 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination.
10. Preparation of Apparatus
10.1 Follow manufacturer’s instructions for mounting and conditioning the column into the chromatograph and adjusting the instrument to the conditions described in Table 2 allowing sufficient time for the equipment to reach equilibrium. See Practices E1510 and E355 for additional information on gas chromatography practices and terminology.
