Sensitive and precise spectrometric determination of ultra-trace elements in metals and alloys with the aid of chemical separation

Analytical procedures by using chemical separation were investigated for determination of ultra-trace elements in high-purity metals and alloys. A reductive co-precipitation method with palladium for electrothermal atomic absorption spectrometry (ET-AAS) was developed for the separation and preconcentration of ultra trace elements. Selenium, tellurium, gold and silver could be quantitatively separated by using ascorbic acid as a reductant. Palladium acts as a carrier of co-precipitation as well as a chemical modifier in ET-AAS. Selenium or tellurium was precipitated as intermetallic compounds with palladium, but gold or silver was precipitated in each metallic state. The proposed method could also be applied to the separation of antimony, germanium and tin by using NaPH2O2 or NaBH4. Removal,methods of blank values were developed for determination of ultra trace carbon and sulfur by infrared absorption after combustion. A nitrogen atmosphere chamber was developed for the determination by using an electric resistance furnace. The amount of carbon on the surface and in the bulk of samples could be respectively determined and cleaning procedures of the sample surface could be investigated. In a determination using an induction-furnace method, the blank values of carbon and sulfur could be drastically reduced by heating an accelerator and a ceramic crucible for combustion. The obtained detection limits were under 0.1 mug g(-1) in all of the developed methods.