A practical routine gas chromatographic determination of phenobarbital, primidone and diphenylhydantoin.

A gas chromatographic method for the routine determination of phenobarbital, primidone and diphenylhydantoin using alkaline extraction and on-column methylation has been developed. The procedure has been optimized for recovery of all three anticonvulsant drugs with particular attention to primidone. Correlation with photometric methods for phenobarbital and diphenylhydantoin show the technique offers significant advantages in both accuracy and precision over other methods.