A direct injection method of plasma samples onto a reverse phase column for the determination of drugs.

Abstract

A reverse-phase HPLC [high-performance liquid chromatography] method which can be applied to the direct analysis of drugs in plasma omitting deproteinizing is proposed. An ODS column treated with human plasma no longer adsorbed plasma proteins from an aqueous solution but still held the characteristics of the reverse-phase column for lipophilic small molecules. This column was used in HPLC analyses and was useful to determine drugs in plasma. The procedure was simple and rapid, and the recoveries of both drugs and proteins were almost quantitative (99-101%) with a good reproducibility. The results obtained for procainamide, 6-mercaptopurine, methotrexate, doxorubicin, theophylline and propranolol in human plasma are summarized.