Determination of gallium in iron meteorites and other iron-rich materials by graphite furnace atomic absorption spectrometry

Abstract

A procedure was developed for the graphite furnace atomic absorption spectrometric determination of gallium in high-iron geological materials such as iron meteorites. To overcome sevre interference from iron, gallium is extracted as a chloro complex from 5 M hydrochloric acid into isobutyl methyl ketone. Iron is reduced by addition of potassium iodide and its co-extraction into the organic phase is thereby decreased to <2%. As determined by analysis of geological reference materials, the limit of detection (3σ) was about 0.05 μg g t-1. The precision (R.S.D.) ranged from 0.8 to 1.1%. The accuracy, as determined from the relative error, ranged from 0.07 to 7.7% for the three standards analysed. In solutions containing 1 μg g −1 gallium, no interferences were observed for up to 1500 μg ml −1 nickel, 1200 μg ml −1 copper, 200 μg ml −1 cobalt, 100 μg ml −1 arsenic and 200 μg ml −1 germanium. The method was applied to the analysis of eight iron meteorites that had been previously analysed by neutron activation analysis. The mean relative deviation of 8.6% was satisfactory.