Ion chromatographic and voltammetric determination of heavy and transition metals in honey

Abstract

Heavy metals in honey are of interest not only for quality control, but can be used also as an environmental indicator. In the present work, in order to minimize sample pre-treatment, the interference by organic constituents of the matrix is overcome by using oxidative UV photolysis. The matrix degrades in less than 1 h, while most common metallic impurities, like iron, copper, nickel, zinc, lead, cadmium and cobalt, remain unaffected by UV radiation, with the exception of manganese. After UV photolysis, the resulting solution is directly analyzed by ion chromatography and differential pulse anodic or cathodic stripping voltammetry. In absence of official standards, the results obtained by these techniques on spiked matrix-matched blank solutions and original and spiked real samples are compared with those of the well established electrothermal atomic absorption spectrometry and they are found in good agreement. The proposed techniques show satisfactory sensitivity, detection limits and standard deviation for heavy and transition metals determination in honey. In addition, both ion chromatography and pulsed voltammetries permit multielement analyses which can be fully automated.