| Abstract: | This work utilizes electrolytic separation and preconcentration of analyte metals on a thin tungsten wire electrode prior to their determination by furnace atomic absorption spectrometry (AAS). Only a very basic electrolysis system operating at constant applied voltages is needed. Following the deposition step, the wire electrode is inserted into the central region of a miniature CRA 90 furnace and electodeposited metals atomized. Tungsten wire melts in the furnace environment at approximately 2500°C and this restricts the range of metals which can be determined by this technique. So far, elements characterized by relatively low atomization temperatures, such as Cd, Zn, Ag, Pb and Cu, have been studied. Sensitivity improvements ranging from 1.5 to 15-fold over the conventional furnace AAS have been achieved with deposition times between 30 and 300 s. No appreciable background absorption has resulted during the atomization step following depositions from NaCl solutions, confirming very efficient separation. The technique has been successfully applied to the determinations of Pb in blood digest and in seawater. Apart from the analytical applications, the wire deposition approach to furnace atomization offers some more fundamental advantages over systems operated in the conventional manner. It can be used to study the atomization behaviour of elements in metallic form in relation to the atomization of their different compounds. Moreover, by rapidly introducing the wire into the furnace preheated to a constant temperature, very fast atomization is achieved with corresponding improvements in analytical sensitivities. The rapid wire introduction technique also lends itself to studies of the removal of sample vapour from furnaces. |
