A rapid hydride-evolution electrothermal atomic-absorption method for the determination of tin in geological materials

A rapid, semi-automated electrothermal atomic-absorption spectrophotometric method involving lithium metaborate fusion and hydride evolution has been developed for the determination of tin in geological materials. The sample is fused with lithium metaborate and brought into solution with hydrochloric acid: the tin in the solution is then converted into its hydride with sodium borohydride in an autosampler. The hydride is decomposed and atomized in an electrically heated quartz furnace, and the atomic absorption of tin at 286.3 nm is measured. The detection limit and the linear working range for tin are 1 ng/ml and 0-140 ng/ml respectively. The method has wide tolerance for variation in reagent concentrations and possible interferences, and when tested on some certified rocks and soils having a wide range of tin values, was found to be satisfactorily accurate and precise. The procedure is now used routinely in our laboratories. At least 10-12 samples can be analysed per hour.