Atomic Absorption Spectrometric Determination of Copper and Nickel in Tea

Abstract

Atomic absorption spectroscopy is one of several analytical tools which can be applied to the determination of less than 20 ppm quantities of copper and nickel in tea. A rapid and accurate atomic absorption method is described which is sensitive to these elements at the levels of interest. After the decomposition of organic matter by oxidation with nitric and perchloric acids, or by dry ashing, a solution is obtained which contains only a few major elements. An average matrix composition is determined and synthetic standards for copper and nickel which are free of potential interferences are prepared for a calibration curve. Tea leaves have been analyzed chemically and by X-ray and optical emission spectroscopy in order to evaluate the accuracy of the atomic absorption method. The average of 50 determinations gives a mean of 11 ppm nickel and 32 ppm copper with standard deviations of ±1.6 σ and 1.8 σ, respectively. The method should be applicable to most organic material.