The qualitative and quantitative analysis of three additives (antioxidant 1010, antioxidant 168 and nucleating agent NA11) in PP were carried out by HPLC-UV simultaneously. Especially, the soxhlet extractor equipment was improved in order to increase the extract efficiency. Through optimizing elution conditions, three chromatographic peaks were totally separated, and correlation coefficients (r) of calibration curves were 0.9979, 0.9975 and 0.9975, respectively, for antioxidant 1010, antioxidant 168 and nucleating agent NA11. Further, the curves of relationship between testing value of three additives left in PP value with actually processing addition were established. Based on quantitative analysis results and these relationship curves, the amount added actually in process in PP could be estimated. The results showed that the correlation coefficient (r) of the relationship curve was higher than 0.95, and the deviations of estimated actual addition were －5.46%, －3.00% and －4.27%, respectively, for antioxidant 1010, antioxidant 168 and nucleating agent NA11.

Key words: antioxidant, nucleating agent, quantitative analysis, actually processing addition