Analytical Sciences

Preconcentration of Gallium by Coprecipitation with Synthetic Zeolites Prior to Determination by Electrothermal Atomic Absorption Spectrometry

Hiroaki MINAMISAWA,* Shinpei IIZIMA,** Mayumi MINAMISAWA,*** Satoshi TANAKA,** Nobumasa ARAI,* and Masami SHIBUKAWA**

*Department of Basic Science and High Technology Research Center, College of Industrial Technology, Nihon University, Shin-ei, Narashino, Chiba 275-8576, Japan
**Department of Applied Molecular Chemistry, College of Industrial Technology, Nihon University, Izumi-cho, Narashino 275-8575, Japan
***Department of Bio Technology, Tokyo College of Medico-Phamaco Technology, Higashikasai, Edogawa, Tokyo 134-8530, Japan

Synthetic zeolites were dissolved in nitric acid, and the resulting solution used as a coprecipitant for the preconcentration of trace amounts of gallium in water samples prior to determination by electrothermal atomic absorption spectrometry (ETAAS). The gallium preconcentration conditions and the ETAAS measurement conditions were optimized. Gallium was quantitatively concentrated with the zeolites coprecipitate from pH 6.0 to 8.0. The coprecipitate was easily dissolved in nitric acid, and an aliquot of the resulting solution was introduced directly into a tungsten metal furnace. The atomic absorbance of gallium in the resulting solution was measured by ETAAS. An ashing temperature of 400°C and an atomizing temperature of 2600°C were selected. The calibration curve was linear up to 3.0 µg of gallium and passed through the origin. The detection limit (S/N ≥ 3) for gallium was 0.08 µg/100 cm³. The relative standard deviation at 1.0 µg/100 cm³ was 3.0% (n = 5). The proposed method has been successfully applied to trace gallium analysis in environmental water samples.

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