3,5′-Bis(dicarboxymethylaminomethyl)-4,4′-dihydroxy-trans-stilbene as a selective spectrofluorimetric reagent for cadmium

Abstract

3,5′-Bis(dicarboxymethylaminomethyl)-4,4′-dihydroxy-trans-stilbene forms fluorescent complexes with aluminium, beryllium, magnesium, calcium, strontium, barium, zinc, cadmium, yttrium, lanthanum, gadolinium and lutetium. All the metal complexes have a metal-to-ligand stoicheiometry of 2:1. Magnesium, calcium, strontium and barium exhibit maximal fluorescence at pH 10·9, with excitation-fluorescence maxima at 360 and 440 nm. Zinc, cadmium, yttrium, lanthanum, gadolinium and lutetium show maximal fluorescence at pH 7·9, with excitation-fluorescence maxima at 360 and 440 nm, and 360 and 430 nm for yttrium and the lanthanons. Aluminium and beryllium show maximal fluorescence at pH 5·2 and 6·4, respectively, with excitation-fluorescence maxima at 345 and 410 nm and 360 and 405 nm, respectively. The formation of the cadmium complex provides a sensitive and selective determination of cadmium in the range 0·5 to 25·0 µg. A simple separation procedure is described in which 3,5′-bis-(dicarboxymethylaminomethyl)-4,4′-dihydroxy-trans-stilbene can be used for the determination of cadmium in the presence of most other metals except lead.