DETERMINATION OF CHROMIUM BY ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY AFTER RAPID MICROWAVE-ASSISTED DIGESTION OF SEDIMENT AND BOTANICAL SAMPLES

Determination of chromium by electrothermal atomization atomic absorption spectrometry with normal electrographite tube has been investigated after microwave-assisted digestion of sediment and botanical samples. Microwave oven-assisted procedures involve digestion with apua regia, HF (for sediments) and H2O2 in a poly(tetrafluoroethylene) (PTFE) reactor followed by treatment with saturated H3BO3 (where HF is used in the earlier step). Comparative studies on the determination of chromium using three previously reported chemical modifiers, Mg(NO3)(2), Pd(NO3)(2) and Triton X-100, and a new modifier NaVO3, have been made. Sodium vanadate was identified as an effective chemical modifier for chromium in botanical samples such as tomato leaves and citrus leaves. Whereas, for river sediment and sewage sludge, chromium has been determined accurately without the need of any chemical modifier. The advantages of the present method are its simplicity, low cost, high speed of sample attack and rapid calibration.