Determination of Cobalt with a Tungsten Tube Atomizer by Electrothermal Atomic Absorption Spectrometry and its use for the Analysis of Biological Materials

 The determination of cobalt by electrothermal atomic absorption spectrometry with a tungsten tube atomizer has been investigated. The absolute characteristic mass (the mass of element giving 0.0044 abs.) of cobalt by the atomizer was 5.8 pg and the detection limit was 0.65 ng/ml (3S/N). The interferences caused by large amounts of interferents like Al, Ca, Cu, Fe, K, Mg, Na, Pb and Zn were evaluated and most of these elements were found to interfere with the cobalt signal. Ammonium thiocyanate as a chemical modifier was found to be efficient to eliminate the severest interferences. The accuracies of the recommended method were found to be almost satisfactory for the determination of cobalt in biological materials, as shown by a comparison with the reported values of NIST materials at the 0.02–0.4 μg/g level. Received August 24, 1998. Revision February 9, 1999.