1.1 This test method covers the determination by gas chromatography of 2,6-ditertiary-butyl para-cresol and 2,6-ditertiary-butyl phenol in new and used insulating liquids at concentrations up to 0.5%. It includes the determination in Type I and II insulating mineral oils as specified in Specification D3487, but has also been used to measure these inhibitors in other insulating liquids, such as esters and high fire-point hydrocarbons. 1.2 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.