Micro determination of opium and strychnos alkaloids is of special interest to toxicologists, pharmacologists and forensic chemists. Among the methods that make use of the precipitation reactions for the quantitation of these alkaloids, radiometric titrations using labelled reagents possess many inherent advantages [1]. Suprisingly, despite their advantageous nature, radiometric titrations are relatively less explored for the determination of alkaloids. Some precipitants like 32P labelled phosphotungstic acid [2], phosphomolybdie acid [3] 110Ag labelled silver nitrate [4] and 131 I labelled iodo complexes of bismuth and mercury [5] have been reported in the literature for the radiometric determination of some alkaloids. But some of the above mentioned reagents require a rigid control of acidity for precipitation. 110Ag labelled silver nitrate reagent can be used only for the halide salts of the alkaloids and free based cannot be titrated with this reagent. Iodo complex of mercury requires a strict delinea...