Minimization of transition metal interferences with hydride generation techniques

A new hydride generator has been characterized for use with the acid-NaBH4 hydride generation systems based on the insertion of a capillary tube into the sample introduction channel of a standard Meinhard nebulizer. The acidic sample and the tetrahydroborate solution are mixed at a merge point 1.5 cm from the end of the nebulizer orifice. Nebulization of the reaction solutions into a 0.7 mi, tubular ''spray chamber'' follows a very short mixing time (less than 0.012 s) of the reagents. This approach permits 10 000 mu g/mL Ni2+ or Cr3+ to be present in the sample solution without producing any interferences. Additionally, in the presence of Fe3+ added as a ''releasing agent'', 5000 mu g/mL Co2+ Or 160 mu g/mL Cu2+ can also be tolerated without interference. An 80 +/- 2% generation efficiency is attained for the test element selenium. A detection limit of 6 mu g/L (3 sigma(b)) is achieved with ICP-AES detection. Precision of replicate measurements at the 12 mu g/L level varies from 5 to 12% relative standard deviation.