Capillary gas chromatographic determination of biperiden in human plasma

A method with internal analogue standardization is described for the determination of 1-(bicyclo[2.2.1]hept-5-en-2-yl)-1-phenyl-3-piperidinopropan-1-ol hydrochloride (biperiden hydrochloride, Akineton). The method involves a multi-step clean-up procedure and subsequent determination by capillary gas chromatography using temperature gradient and nitrogen-sensitive detection. There is no interference by plasma components and biperiden metabolites in plasma extracts. When using a 2-ml sample the lower limit of detection is 0.09 ng/ml, the lower limit of determination about 0.25 ng/ml. Interassay variation coefficients decrease from approximately 14% at the lowest concentration to about 7% at 1.2 ng/ml and above.