Study of chromogenic reaction of cadmium with meso-tetrakis [3,5-bis (trifluoromethyl) phenyl] porphyrin

Meso-tetrakis [3,5-bis (trifluoromethyl) phenyl] porphyrin [T(3,5-DTFMP)P] for the spectrophotometric determination of trace cadmium has been studied. The experimental results showed that the reaction was completed by heating at 100 ℃ for 7 min in an alkaline solution of pH 10.60. It was a sensitive and selective chromometric reagent for the direct determination of cadmium in the presence of Tween-80 and o-phenanthroline. Its apparent molar absorptivity e_(442) is 2.19×10~5 L·mol~(-1)·cm~(-1). Beer′s law is obeyed in the range of 0～3 μg of per 25 mL. This method has been successfully applied to the determination of cadmium in tobacco.