ASTM D7057-2018 pdf free download

ASTM D7057-2018 pdf free download.Standard Test Method for Analysis of Isopropylbenzene (Cumene) by Gas Chromatography (External Standard)
1. Scope
1.1 This test method covers the determination of the purity of isopropylbenzene (cumene) by gas chromatography. Cali- bration of the gas chromatography system is done by the external standard calibration technique. 1.2 This test method has been found applicable to the measurement of impurities such as nonaromatic hydrocarbons, benzene, toluene, ethylbenzene, phenol, cymenes, t-butylbenzene, n-butylbenzene, n-propylbenzene, alpha- methylstyrene, sec-butylbenzene, and diisopropylbenzenes, which are impurities that can be found in isopropylbenzene. The latter impurities can be analyzed over a range of 1 mg/kg to 500 mg/kg by this method (see Table 1). The limit of quantitation averages 3.8 mg/kg while the limit ofdetection for these impurities averages 1.1 mg/kg. 1.3 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 E29. 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5 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 hazard statements, see Section 8. 1.6 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 1.2 and for use as an internal quality control tool where isopropylbenzene is produced or is used in a manufacturing process. It may also be used in development or research work involving isopropylbenzene. 5.2 This test method is useful in determining the purity of isopropylbenzene with normal impurities present. If extremely high boiling or unusual impurities are present in the isopropylbenzene, this test method would not necessarily detect them and the purity calculation would be erroneous. 5.3 Cumene hydroperoxide, if present, will yield thermal decomposition products, primarily AP and DMPC as stated in 4.1, that will elute in the chromatogram thereby giving incorrect results unless they are excluded as indicated in 4.1. It is also possible to get erroneous results for trace alpha- methylstyrene present in isopropylbenzene if the inlet has become unduly contaminated with non-volatile foreign sub- stances. 5.4 The nonaromatic hydrocarbons commonly present from the isopropylbenzene manufacturing process, particularly a non-zeolitic one, will interfere with the determination of xylenes (if present).
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 isopropylbenzene. The column described in Table 2 has been used successfully and shall be used as a referee in cases ofdispute. Unless the analyst can be sure of peak identity, for example by gas chromatography-mass spectrometry (GC-MS), the use of the column in Table 2 is strongly recommended. 6.3 Recorder—Chromatographic data systems are preferred but electronic integration may be used if the user can demon- strate that the results are consistent with the precision state- ment. Recorders are not considered adequate for meeting the precision requirements of this standard. 6.4 Injector—The specimen must be precisely and repeat- edly injected into the gas chromatograph. An automatic sample injection device is highly recommended. Manual injection can be employed if the precision stated in Table 1, Summary of Precision Data, can be reliably and consistently satisfied.