Electron-capture detector GLC technique for estimating tocainide in biological fluids.

A sensitive and specific electron-capture detector GLC method capable of detecting picogram quantities of tocainide, a lidocaine analog, in biological fluids was developed. This method consists of extracting the compound into methylene chloride and derivatizing with heptafluorobutyric anhydride to form the monoheptafluorobutyryl derivative. The derivative formation was confirmed by GLC-mass spectrometry. Quantitative estimation was performed using 1-bromonaphthalene as an internal standard. The minimum detectable level by the electron-capture method was approximately 30 pg/injection as opposed to approximately 3 ng/injection with a flame-ionization detector Linear response was observed in the range from 50 pg to 3 ng using an electron-capture detector. No interference from endogenous substances was observed.