Determination of tin by in situ trapping of stannane on a resistively heated iridium treated tungsten coil surface and interference studies.

A novel method was developed for the in situ trapping of stannane on an iridium-coated tungsten coil. Coating the tungsten coil with iridium has significantly improved the sensitivity. The tungsten coil can either be used as an on-line atomizer or as a trapping surface. The interference effect of some hydride-forming elements such as, As(III), Se(IV), Te(IV), Sb(III) was investigated. The interference effect of Sb(III) and Se(IV) could not be completely eliminated using in situ trapping mode but the magnitude of their interferences was reduced significantly when compared to quartz T-tube atomizer. The limit of detection with iridium-coated tungsten coil for a 60s trapping period (sample volume 6 ml) was found to be 0.065 ng ml(-1) and the calibration was linear over the range of 0.5-4.0 ng ml(-1). The precision of the analytical method was determined to be 2.2% RSD (n=11) for 1.0 ng ml(-1) Sn concentration. Analytical performance of the proposed method was checked by analyzing tap water, spring water and mineral water samples for Sn. The accuracy of the method was tested with two different certified reference materials; fortified water TMDA 61 (NWRI) and Dogfish Liver DOLT-3 (NRC). The results were in a good agreement with the certified values at 95% confidence level.