ASTM D5524-94

Separation and identification of stabilizers used in the manufacture of HDPE are necessary in order to correlate performance properties with polymer composition. This test method provides a means of determining BHT, BHEB, Isonox 129, Irganox 1010, and Irganox 1076 levels in HDPE samples. This test method should be applicable for the determination of other antioxidants such as Cyanox 425, Cyanox 1790, Cyanox 2246, Ultranox 236, and Ultranox 246, but the applicability of this test method has not been investigated for these antioxidants.

The additive-extraction procedure is made effective by the insolubility of the polymer sample in solvents generally used for liquid chromatographic analysis.

The lowest level of detection for a phenolic antioxidant is approximately 2 ppm under optimum conditions.

Other procedures that have been used successfully to remove additives from the plastics matrix include thin-film, microwave,¹⁰ ultrasonic,¹¹ and supercritical fluid extractions.^{11 , 12 , 13} Procedures other than HPLC have been used successfully to separate additives, including SFC¹³ and capillary GC.¹⁴

1.1 This test method covers a liquid-chromatographic procedure for the separation of some additives currently used in high-density polyethylene. These additives are extracted with cyclohexane prior to liquid-chromatographic separation. The ultraviolet absorbance (200 nm) of the compound(s) is measured; quantitation is performed using the internal standard method.

Note 1—There is no similar or equivalent ISO standard.

1.2 The values stated in SI units are to be regarded as the 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.