SENSITIVE DETERMINATION OF SELENIUM BY INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY WITH FLOW-INJECTION AND HYDRIDE GENERATION IN THE PRESENCE OF ORGANIC-SOLVENTS

Parameters for selenium determination in inductively coupled plasma ma ss spectrometry (ICP-MS) by pneumatic nebulization and how injection w ith hydride generation (FI-HG-ICP-MS) have been compared. The effect o f organic solvents (methanol, ethanol, propanol, acetone and acetonitr ile) on the Se response has been evaluated with both sample introducti on modes, Results show that the addition of alcohols leads to an impor tant reduction of polyatomic interferences ((ArCl)-Ar-40-Cl-31,(ArAr)- Ar-40-Ar-38, (Ar2H2)-Ar-40) and to a 10-fold enhancement of the Se sig nal. The effect of the solvent on both signal enhancement and reductio n of the interference mechanisms are discussed. Under optimized operat ing conditions (NaBH4 = 0.2%, pH1, methanol load = 6%), selenium deter mination by FI-HG-ICP-MS gives detection limits (3 s(b)) of 1 pg for a 200 mu l sample loop with an average RSD of <2% ender routine conditi ons. This system has been validated by participation in a certificatio n campaign throughout Europe for inorganic selenium, It has also been applied to the direct determination of dissolved Se-IV in natural estu arine waters.