IMPROVED THALLIUM HYDRIDE GENERATION USING CONTINUOUS-FLOW METHODOLOGIES

The use of continous flow vapour generation to improve the determinati on of thallium by atomic spectrometry has been investigated. Attempts to generate volatile organothallium compounds were unsucessful but usi ng sodium tetrahydroborate a volatile thallium species was produced. E vidence was obtained to suggest that the vapour phase species was thal lium(I) hydride, TlH. At room temperature noisy I signals were obtaine d, but when the reaction manifold was chilled to 0 degrees C the signa ls were far more stable. Cooling did not significantly change the sens itivity. A characteristic concentration of 4 ng cm(-3) was obtained fo r continous bow vapour generation determination of thallium by atomic absorption spectrometry (AAS). This is a 1500-fold improvement on the previous sensitivity for batch vapour generation AAS. Continous vapour generation also appears to eliminate any serious interferences from o ther hydride-forming elements. Flow injection of nitric acid between s amples;was used to remove memory effects.