Hydride Generation in Merging Chamber for Determination of Picogram Amounts of Bismuth by Inductively Coupled Plasma Mass Spectrometry

A combination of bismuth hydride generation with a merging introduction technique, where analytes are merged with spray mist from a nebulizer on the way to ICP, has been developed for sensitive determination of bismuth. A sample solution of 20 µl was led to a reaction cell inside a merging chamber and was mixed with reductant solution. The generated bismuth tetrahydride was transported to and measured by ICP-MS. With the adoption of flow system, a cyclic procedure of introductions of solutions, reactions and evacuations could be performed sequently with keeping ICP power on. The effects of acidity and volumes of sample solution and reductant on the signal were investigated in detail. The signal intensity was proportional to the amount of bismuth in solution loaded on a reaction cell in the merging chamber. The absolute detection limit of bismuth using reductant of analytical grade was 72 fg, which corresponds to 1.8 ppb in 40 µl solution. The present method was applied to the solutions of digested standard rocks. Results with good precision and accuracy were obtained.