ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRIC DETERMINATION OF ULTRA-TRACE AMOUNTS OF TIN BY IN-SITU PRECONCENTRATION IN A GRAPHITE TUBE USING FLOW-INJECTION HYDRIDE GENERATION WITH ONLINE ION-EXCHANGE SEPARATION

A method was developed for the ultra-trace determination of tin by in situ preconcentration in a graphite tube using a flow injection hydride generation technique with on-line ion-exchange separation. The sample was prepared in 2M hydrochloric acid before being passed through an incorporated micro-column packed with a strongly basic anion-exchanger D-201. The tin was retained as its chlorostannate complex and subsequently eluted by de-ionized water into the hydride generation system. The hydride and hydrogen gases evolved were separated from the liquid phase in a gas-liquid separator and transferred into a palladium-coated graphite tube pre-heated to 300 degrees C to collect the analyte, which was later atomized at 2300 degrees C. With the reported system, tin was determined at a sampling frequency of 30/hr with a detection limit (3 sigma) of 0.01 mu g/l. using 10.7 ml sample. The precision was 1.5% RSD at the 0.5 mu g/l. level. The proposed method was applied to the determination of tin in tap water, hair, serum samples and geological reference samples.