4.1 p-tertiary-butylcatechol is commonly added to commercial butadiene in amounts of 50 mg/kg to 250 mg/kg as an oxidation inhibitor. This test method is suitable for use by both producers and users of butadiene within the limitations described in Section 1.

1.1 This test method covers the determination of total p-tertiary-butylcatechol inhibitor added to polymerization and recycle grades of butadiene or to other C₄ hydrocarbon mixtures containing no phenolic material other than catechol or no oxidized phenolic material other than that derived from oxidation of catechol. In general, all phenols and their quinone oxidation products are included in the calculated catechol content. Small amounts of polymer do not interfere. This test method is applicable over the range of TBC from 50 mg/kg to 500 mg/kg.

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

1.3 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.4 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.