Separation and identification of stabilizers used in the manufacture of polypropylene is necessary in order to correlate performance properties with polymer composition. This test method provides a means to determine erucamide slip, Vitamin E, Irgafos 168, Irganox 3114, Irganox 1010, and Irganox 1076 levels in polypropylene samples. This test method is also applicable for the determination of other antioxidants, such as Ultranox 626, Ethanox 330, Santanox R, and BHT, 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.

Under optimum conditions, the lowest level of detection for a phenolic antioxidant is approximately 2 ppm.

Note 2-Other methods that have been used successfully to remove additives from the plastics matrix include thin film, microwave, ultrasonic, and supercritical fluid extractions. Other methods have been used successfully to separate additives including SFC and capillary GC.

Irgafos 168 is a phosphite antioxidant. Phosphites are known to undergo both oxidation and hydrolysis reactions. Less Irgafos 168 may be seen in the polymer than originally added to the polymer due to oxidation during processing. The HPLC separation is capable of separating the phosphite, phosphate (oxidation product), and hydrolysis product and quantify them if standards are obtained. No significant breakdown of the phosphite antioxidant has been seen due to either extraction technique or the separation presented in this standard.