5.1 The determination of oxygenates is important in the manufacture of ethene, propene, 1-3 butadiene, C4 hydrocarbons, and C5 hydrocarbons. Alcohols, ethers, aldehydes, and ketones are trace impurities in these hydrocarbons. Oxygenates decrease catalyst activity in downstream polymerization processes.

1.1 This test method covers the gas chromatographic procedure for the quantitative determination of organic oxygenates in C2, C3, C4, and C5 matrices by multidimensional gas chromatography and flame ionization detection. This test method is applicable when the hydrocarbon matrices have a final boiling point not greater than 200 °C. Oxygenate compounds include, but are not limited to, those listed in Table 1. The linear working range for oxygenates is 0.50 mg/kg to 100 mg/kg.

TABLE 1 Oxygenates and Typical Retention Times

Components

Retention Time (min)

Dimethyl ether

6.18

Diethyl ether

8.44

Acetaldehyde

8.89

Ethyl tert-butyl ether

10.66

Methyl tert-butyl ether (MTBE)

10.92

Diisopropyl ether

11.22

Propionaldehyde (Propanal)

12.00

Tertiary amyl methyl ether (TAME)

13.19

Propyl ether

14.00

Isobutylaldehyde

14.10

Butylaldehyde

14.50

Methanol

14.91

Acetone

15.39

Isovaleraldehyde

16.00

Valeraldehyde

16.10

2-Butanone (MEK)

17.14

Ethanol

17.51

N-propyl alcohol and isopropanol

19.20 (co-elution)

Allyl Alcohol

20.00

Isobutanol, Tert-butyl alcohol, Sec-Butanol

20.24 (co-elution)

N-butanol

20.84

1.2 This test method is intended to determine the mass concentration of each oxygenate in the hydrocarbon matrix. Oxygenate compound identification is determined by reference standards and column elution retention order.

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.4 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.

1.5 This 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.