This test method is designed to determine the nitrogen content of oligomeric 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ) antioxidant. TMQ is used for heat protection of vulcanized rubber.

This test method is suitable for assessing product specifications since nitrogen content is related to product performance, that is, antioxidant efficiency and heat protection. For comparison of product quality at different production facilities sufficient interlaboratory accuracy and precision are required.

1.1 This test method covers the determination of the nitrogen content of polymerized 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ). It is based on a potentiometric titration of an acetone solution of TMQ with perchloric acid in acetic acid.

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 and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 9.