Simultaneous Measurement of Diphenylhydantoin and Primidone in Serum by Gas—Liquid Chromatography

Abstract

The need for simultaneous determination of the concentration of diphenylhydantoin (Dilantin) and primidone (Mysoline) in serum is frequently expressed to the clinical chemistry laboratory. Isothermal gas-liquid chromatography (GLC) has been used to develop a rapid, specific method. The method involves a single extraction and no derivative formation. The procedure is simple enough to be used with large numbers of samples. Detection limits for the method are 0.3 µg diphenylhydantoin per ml and 0.1 µg primidone per ml. The mean precision of the method is 6.2% and 4.8%, expressed as the coefficient of variation, for diphenylhydantoin and primidone, respectively. Barbiturates and glutethimide added to serum samples did not interfere with the analysis. The method has been used for more than 500 patients without interferences from metabolites, and meets all criteria for routine and emergency use.