A CRITICAL-EVALUATION OF A MULTIELEMENT ETAAS SYSTEM USING LINE SOURCES AND A TRANSVERSELY HEATED GRAPHITE ATOMIZER WITH ZEEMAN-EFFECT BACKGROUND CORRECTION

A simultaneous, multielement, electrothermal atomic absorption spectro metry (ETAAS) system has been constructed and evaluated. The system co nsists of a spatially isothermal, transversely heated graphite atomize r with integrated platform (THGA) and Zeeman effect background correct ion, mounted in an echelle polychromator. Up to four line sources coul d be combined using beam splitters. Using multielement atomization con ditions, characteristic mass values are similar to those obtained with conventional, line source ETAAS using the THGA, but the detection lim its are, on average, an order of magnitude poorer. The latter results from a lower radiation flux through the polychromator and light losses in the optical system, and design modifications are suggested to impr ove these aspects of the system performance. A further drawback with t he instrument described, and a general disadvantage of line source AAS , is the short working range. This problem, as well as methods to exte nd the working range, are discussed. The instrument has been applied t o the simultaneous determination of Cd, Cu and Pb in sea-water samples following preconcentration and matrix separation in a flow injection system, demonstrating the potential benefits of multielement ETAAS.