Electrothermal vaporization system using furnace-fusion technique for the determination of lead in botanical samples by inductively coupled plasma atomic emission spectrometry

A new approach to sample digestion, subsequent vaporization and introduction into an inductively coupled plasma atomic emission spectrometer was developed for the direct determination of lead. To each small sample cuvette made of tungsten, a mixture of a ground solid sample and powdered diammonium hydrogenphosphate was precisely weighed. The cuvette was positioned onto the tungsten boat furnace (TBF) incorporating a vaporizer. Tetramethylammonium hydroxide solution was added. Then the cuvette was heated and maintained at a wet-digestion temperature to decompose the solid sample. After digestion, the temperature was elevated to generate the analyte vapor for introduction into a plasma. Since the solid samples were wet-digested in the sample cuvettes before vaporization, they could be analyzed by using a calibration curve prepared from aqueous standard solutions. This method was applied to the determination of lead in several biological materials with satisfactory results.