Preconcentration of Gallium(III) and Indium(III) by Coprecipitation with Hafnium Hydroxide for Electrothermal Atomic Absorption Spectrometry

Abstract

The trace amounts of gallium and indium in water were determined by graphite furnace atomic absorption spectrometry after being concentrated by the coprecipitation technique with hafnium hydroxide. Hafnium hydroxide coprecipitates quantitatively 0.2 -3 ng of gallium from 50 - 400 ml of sample solution at pH 6.0-10.5 and 0.2 -4 ng of indium from 50 - 400 ml at pH 6.0-11.0. The atomic absorbances of gallium and indium are increased about 3 times by the presence of hafnium; the reproducibilities of the measurements are also improved. The calibration curve is linear from 8 to 120 ng ml-1 of gallium or from 8 to 160 ng ml-1 of indium. Twenty seven diverse ions tested did not interfere seriously with either element. These methods are applicable to the determination of gallium and indium in river or seawater which contains down to 0.5 ng ml-1 of these elements. © 1988, The Japan Society for Analytical Chemistry. All rights reserved