Determination of serum proxiphylline by high-pressure liquid chromatography

A specific, simple and rapid high-pressure liquid chromatographic method has been developed for the quantitation of proxiphylline in serum. Other methylated xanthines, and a variety of drugs commonly used in the treatment of obstructive lung diseases, do not interfere with the analysis. Protein precipitation with trichloroacetic acid is the only pre-treatment of the sample required before injection. The time necessary to analyse one serum sample is half an hour including sample preparation, chromatographic running and calculation of the drug concentration. The method can therefore be used as an emergency analysis. The detection limit of proxiphylline is 50 pmol injected into the chromatotograph, and as little as 10 microliter serum can be analysed. The method can also be used for the quantitation of theophylline.