Multiple probe concentrating of Au and Pd in geological samples for atomic absorption determination with two-stage probe atomization

Abstract

The two-stage probe atomization (TPA) technique for Au and Pd determination in geological samples by graphite furnace atomic absorption spectrometry (GFAAS) has been developed. Making use of TPA permitted Au and Pd determination in rocks and ores in the form of suspensions obtained by partial sample digestion in aqua regia. Concentrating of analytes on tungsten probe decreases matrix effects and relieves from the necessity of full sample digestion or preparatory matrix removing like extraction or sorption, reducing an analysis time from a few days to an hour and a half. The analytical signal dependence on number of concentrating cycles has been studied. Multiple concentrating of analytes on tungsten probe surface decreased limits of detection by 5 times compared with earlier results in TPA-GFAAS and expanded the range of Au and Pd concentrations which can be determined in rocks and ores by this technique. The achievable detection limits were found to be 3 × 10−3 and 7 × 10−3 μg/g for Au and Pd, respectively. The accuracy of method was confirmed by analyses of certified reference materials (CRMs) using the standard addition method. The relative standard deviation for 0.64 μg/g Au concentration was 6.0% and 6.5% for 0.30 μg/g Pd concentration (n = 5). The rapidness of the technique makes it rather important for industrial interest.