[Determination of theophylline, phenobarbital and valproic acid by chromatographic and immunologic technics....

Theophylline, phenobarbitol, and valproic acid serum levels were measured from plasma samples using chromatographic (HPLC and GC) and by immunologic techniques using enzyme kinetics (EMIT) or fluorescence polarization (FPIA). Results of these various methods differ when examined by more stringent statistical analysis. These differences do not appear to be clinically important except possibly for valproic acid the case in employing immunologic methods as well as their rapidity render these techniques particularly useful for therapeutic surveillance.