[Gas chromatographic determination of phenytoin, phenobarbital and primidone: flash-methylation after direct addition of trimethyl-phenyl-ammonium hydroxide to the ethyl acetate extract (author's transl)].

25 microliters plasma, 25 microliters internal standard and 5 microliters sodium dihydrogenphosphate solution are extracted with 100 microliters ethyl acetate. 40 microliters of the extract are mixed with 10 microliters trimethyl-phenyl-ammoniumhydroxide (0.1 mol/l methanol). 3 microliters of this solution are injected for gas chromatography using a nitrogen-specific detector. Trimethyl-phenyl-ammoniumacetate appears to be a satisfactory methylating agent for these drugs in the injection port of the gas chromatograph.