DETERMINATION OF TRACE LEVELS OF COBALT I N SILICATE ROCK SAMPLES BY GRAPHITE-FURNACE AAS AND COMPARISON WITH ICP-AES AND MICROWAVE-INDUCEDPLASMA MS

A convenient analytical method for the determination of trace amounts of cobalt in geological samples was investigated by atomic absorption spectrometry (AAS) equipped with a pyro-graphite furnace. In order to obtain accurate analytical results, two methods of preparing calibrati on curves, the standard addition method and the matrix matching method , were examined in detail by using the standard geological samples iss ued from the Geological Survey of Japan (GSJ; JA-1, Ja-3, JG-3 and JG- 1a). The analytical results obtained by AAS were ascertained by using an inductively coupled plasma atomic emission spectrometry (ICP-AES) e quipped with an ultrasonic nebulizer and microwave induced nitrogen pl asma mass spectrometry (MIP-MS). The proposed method was applied to th e determination of cobalt at 1 mu g/g levels in geological samples whi ch will be certified by the Korea Institute of Energy and Resources (K IER; KG-1 and KG-2). The detection limit (three times of relative stan dard deviation of blank) for cobalt was 5.3 mu g/l when 10 mu l of sol ution was measured. The precision for the determination (relative stan dard deviation at 5 determinations) of cobalt was 0.4 similar to 3.4% when standard geological samples were analyzed.