A GLC-nitrogen phosphorous detector assay for trifluoperazine in plasma

A GLC-nitrogen phosphorous detector (NPD) method for the quantitative determination of trifluoperazine in plasma is described. It depends on an organic extraction of trifluoperazine and the internal standard prochlorperazine from basified plasma. Following the extraction, the organic solvent is evaporated to dryness and the residue is reconstituted in a small volume of methyl alcohol. GLC analysis of aliquots of the methanolic solution using a NPD permitted the determination of 0.5 ng/ml of trifluoperazine in plasma. Standard curves for trifluoperazine over a concentration range of 0.5 to 15 ng/ml of plasma were linear with an overall variation coefficient of 5.3%. In isolated samples obtained from a normal healthy volunteer, application of this method to plasma concentration determinations after oral administration of a 5-mg trifluoperazine tablet, is demonstrated and compared with the concentrations obtained by GLC-mass spectrometry and radioimmunoassay procedures.