Determination of Amphetamine and Phentermine in Biological Fluids

Abstract

Techniques are described for a reliable measurement of amphetamine and phentermine at the concentration levels found in blood and urine following the administration of therapeutic doses. An extraction and GC measurement provides a simple, direct method for the determination of the drugs in the urine, but lower concentration in blood requires procedural adaptations. Using coated glassware, co-precipitating with a scavenger amine, forming a hydrochloride salt, and utilizing an internal standard counteract irreversible adsorption, volatility, and incomplete derivatization. Formation of the trifluoroacetamide derivative provides a symmetrical peak for the GC analysis. Critical investigation of each of the steps of the procedure indicated that the method permits complete and consistent recovery of the amine from blood samples. Adequate sensitivity of the method is shown by data derived from subjects administered therapeutic doses of amphetamine or phentermine.