1.1This test method covers the determination of the purity of AMS (α-methylstyrene) by gas chromatography. Calibration of the gas chromatography system is done by the external standard calibration technique.
1.2This test method has been found applicable to the measurement of impurities such as cumene, 3-methyl-2-cyclopentene-1-one, n-propylbenzene, tert-butylbenzene, sec-butylbenzene, cis-2-phenyl-2-butene, acetophenone, 1-phenyl-1-butene, 2-phenyl-2-propanol, trans-2-phenyl-2-butene, m-cymene, p-cymene, and phenol, which are common to the manufacturing process of AMS. The method has also been found applicable for the determination of para-tertiary-butylcatechol typically added as a stabilizer to AMS. The impurities in AMS can be analyzed over a range of 5 to 800 mg/kg by this method. (See Table 1.) The limit of quantitation for these these impurities averages 4 mg/kg, while the limit of detection averages 1.2 mg/kg. (See Table 1.)
TABLE 1 Summary of Precision Data (mg/kg)
| Compound | Repeatability (r) | Reproducibility (R) | Range Studied |
| | | | |
| Acetone | 1.61 + 0.035*Acetone | 0.47 + 1.10*Acetone | 0.5 – 26 |
| Cumene | −0.46 + 0.031*Cumene | 7.88 + 0.19*Cumene | 45 – 290 |
| nPropylbenzene (NPB) | 2.11 + 0.03*NPB | −7.81 + 0.37*NPB | 55 – 195 |
| Phenol | 1.84 | 3.65 + 0.58*Phenol | 1 – 40 |
| tertButylbenzene (TBB) | −1.22 + 0.035*TBB | 3.63 + 0.087*TBB | 150 – 650 |
| secButylbenzene (SBB) | 4.23 + 0.019*SBB | 21.60 + 0.25*SBB | 200 – 765 |
| mCymene | 0.31 + 0.035*mCymene | 2.34 + 0.35*mCymene | 2 – 50 |
| oCymene | 1.63 | 8.00 | 29 – 31 |
| pCymene | 5.12 | 15.79 | 10 – 18 |
| cis-2-Phenyl-2-Butene (CPB) | 0.17 + 0.030*CPB | 5.39 + 0.11*CPB | 50 – 225 |
| trans-2-Phenyl-2-Butene (TPB) | 1.57 | 0.54 + 0.20*TPB | 19 – 70 |
| 1-Phenyl-1-Butene (PB) | 4.00 + 0.018*PB | 0.17 + 0.19*PB | 0.2 – 735 |
| Acetophenone (AP) | –1.09 + 0.15*AP | 1.17 + 0.63*AP | 15 – 115 |
| para-tert-Butylcatechol (PTBC) | 2.21 | 17.82 | 10 – 19 |
| 2-Methylbenzofuran (MBF) | 0.33 + 0.76*MBF | 0.75 + 0.60*MBF | 1 – 2 |
| 2-Phenylpropion aldehyde (PPA) | 0.59 + 0.11*PPA | 0.29 + 0.23*PPA | 1.5 – 15 |
| α-Methylstyrene Oxide (AMSO) | 4.61 | 6.51 + 0.23*AMSO | 13 – 32 |
| DimethylBenzyl Alcohol (DMBA) | 0.38 | 0.55 + 2.03*DMBA | 0.1 – 1 |
1.3In 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.
1.4The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5This standard does not purport to address all 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 Section 8.
1.6This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.