SPECTROPHOTOMETRIC DETERMINATION OF ZINC IN PHARMACEUTICAL PREPARATIONS AND IN WATER USING 1-(PHENYL-2-PYRIDYL) CARBYLIDENE-5-SALICYLIDENE THIOCARBOHYDRAZONE

A simple, fast and reliable spectrophotometric method for the determin ation of zinc in natural waters and pharmaceutical preparations is pro posed. The procedure is based on the use of a derivative of thiocarboh ydrazide 1-(phenyl-2-pyridyl)carbylidene-5-salicylidene thiocarbohydra zone (PPST). The yellow complex formed at pH 6.5 in a medium containin g an acetate buffer and 48% (v/v) dimethylformamide exhibits maximum a bsorbance at 424 nm. Molar absorptivity is 61.000 l.mol-1.cm-1 and the detection limit is 0.010 mug/ml. The effect of interference is studie d and the method was successfully applied to the determination of zinc in nine natural waters from south-west Spain and in five pharmaceutic al preparations.