Improved gas-liquid chromatographic method for the determination of baclofen in plasma and urine

A simple, rapid and sensitive assay for baclofen analysis has been developed. Baclofen and the internal standard are analyzed by gas-liquid chromatography with electron-capture detection after esterification of the carboxyl group to the butyl ester and acylation of the amino group to the pentafluoropropionylamide. Recovery from biological matrixes is accomplished by ion-pair extraction. The limit of quantitation of the entire assay as stated is about 10 ng/ml baclofen in plasma.