Quantitative analysis of residual synthetic polystyrene adsorbent in drugs by Curie-point pyrolysis gas chromatography

Residual synthetic adsorbent, cross-linked polystyrene, used in drug purification has been analyzed quantitatively by Curie-point pyrolysis gas chromatography. The peaks of intact polystyrene adsorbent in the pyrogram were used as key peaks for quantitative measurement of residues of the adsorbent in vitamin B-1 and streptomycin sulfate. It was shown that the m-ethylstyrene or p-ethylstyrene peaks in the pyrolyzates were suitable for determination of polystyrene adsorbent content. The levels of residual adsorbent in the drugs were found to be < 0.1 %, the value stipulated by the International Conference on Harmonization (ICH). In quantitative evaluation of an adsorbent content of 0.1 % the precision was 3.6 % and 2.7 % for vitamin B-1 and streptomycin sulfate, respectively.