Evaluation of a direct solid sampling atomic absorption spectrometer for the trace determination of mercury in geological samples

This paper reports the evaluation of a new cold vapour atomic absorption spectrometer applied to the direct determination of Hg in geological materials. The AMA-254 is based on thermal decomposition of the sample and collection of the evolved Hg vapour on a gold amalgamator. A suite of 33 reference materials, including rocks, soils, sediments and coal, was analysed in duplicate, using sample masses ranging from ca, 30 to 300 mg. Agreement with recommended values was good for all but one sample, TILL-1, where this method produced high results of 145 mu g kg(-1) Hg compared to a proposed value of 92 mu g kg(-1) obtained by HCL-HNO3 digestion. Precision, over the range of Hg in these samples of 4 to 6250 mu g kg(-1), was shown to be 10% (+/-5% RSD). Cycle time was 5 min per sample.