Furnace-fusion system for the direct determination of cadmium in biological samples by inductively coupled plasma atomic emission spectrometry using tungsten boat furnace–sample cuvette technique

Abstract

A solid sampling technique using an electrothermal vaporisation device is described. To a small sample cuvette made of tungsten, a solid mixture of a biological sample and diammonium hydrogenphosphate powder as a fusion flux was added. The cuvette was superposed on a tungsten boat furnace, then tetramethylammonium hydroxide solution was injected as a sample decomposition reagent. By resistance heating of the tungsten boat furnace, the cuvette temperature was maintained at a wet-digestion temperature sufficient to decompose the solid sample. After the on-furnace digestion was complete, the temperature was successively elevated up to maximum to generate analyte vapour. The transient cloud of vapour was introduced into the plasma. Since any solid samples could be decomposed to ash completely on the cuvette, the sensitivity was the same as that of aqueous standards. The method was successfully applied to the direct determination of cadmium in biological certified reference materials.