INDIRECT FLAME ATOMIC-ABSORPTION SPECTROMETRIC DETERMINATION OF PAPAVERINE, STRYCHNINE AND COCAINE BY CONTINUOUS PRECIPITATION WITH DRAGENDORFF REAGENT

A flow injection method for the determination of papaverine, strychnin e and cocaine based on the precipitation of ion pairs formed between t he alkaloid and Dragendorff's reagent, BiI4-, is proposed. The precipi tate is obtained by injecting the BiI4- complex (precipitating reagent ) into a carrier stream containing the alkaloid and is subsequently re tained on a filter. In this way, the drugs can be determined over the ranges 1.5-18, 4-60 and 6-100 mug ml-1 for papaverine, strychnine and cocaine, respectively, with a relative standard deviation of between 1 .1 and 2.1% and a sampling frequency of 100 h-1. The proposed method w as applied to the determination of papaverine in pharmaceutical prepar ations using flame atomic absorption spectrometry.