Differential-pulse polarographic determination of heavy metals released from ceramic glazes

Abstract

Inorganic oxides are commonly used for glazing ceramic ware and may contaminate food and beverages. Lead, zinc and metals used for colouring purposes (such as cadmium, chromium, cobalt, copper, iron, manganese and nickel) are leached from glazed ceramic surfaces with 4%V/V acetic acid over a 24-h period at room temperature. The released metal ions are determined simultaneously in acetic acid or acetate buffers by means of differential-pulse polarography. The influence of some parameters, such as pH variation or the presence of surfactants, is shown.

Calibration graphs are linear over the range 0–500 µg ml^–1. The proposed method is simple and allows an easy determination of 0.5 µg ml^–1 of cobalt(II), 0.3 µg ml^–1 of chromium(III), 0.1 µg ml^–1 of lead, nickel(II) and iron(III) and 0.05 µg ml^–1 of cadmium, copper, zinc and manganese(III), with a precision of ±2–3%.