Determination of Copper, Lead and Cadmium in Tea by Graphite Furnace Atomic Absorption Spectrophotometry

Abstract

A method for determination of copper, lead and cadmium in tea by graphite furnace atomic absorption spectrophotometry with higher sensitivity was examined. Samples ashed at 500°C were used throughout the experiment.
When lead and cadmium were analysed, the pre-atomization at high temperature(above 2100°C)was required before each load of the sample solution. The addition of sodium chloride and potassium chloride to a 1N-HCl solution containing 100ppb of lead interfered the determination of lead. And the lead content of the sample solution in 1N-HCl could not be determined either. But that of the sample solution in 1N-HNO₃ could be determined, because the interference was a little compared with that in 1N-HCl. When copper, 1ead and cadmium were extracted by the Iodide-MIBK extraction method, there was no interference with the determination. When the copper, lead and cadmium contents of 54 samples obtained from various producing districts were determined by this method, the means of copper, lead and cadmium were 11.9μg/g, 0.31μg/g, and 0.023μg/g, respectively. The values of lead and cadmium analysed by graphite furnace were slightly low compared with those by atomic absorption spectrophotometry using air-acetylene flame.