Improvement of selenium determination in water by inductively coupled plasma mass spectrometry through use of organic compounds as matrix modifiers

The effect of organic modifiers such as monofunctional alcohols, polyalcohols and organic acids on selenium response intensity and on polyatomic interferences by inductively coupled plasma-mass spectrometry (ICP-MS) has been evaluated and the possible mechanisms discussed. It has been proved that the addition of small amounts ( < 4%) of methanol, ethanol, sugar, ethylene glycol and tartaric acid, in combination with instrumental adjustments, significantly improves the Se/polyatomic interference signal ratio. The 40 Ar 37 Cl + interference is significantly alleviated by addition of 4% lactic acid or 4% glycerol, the Se/ArCl ratio with the latter being even higher than in the absence of chloride. Se sensitivity and detection limits are improved about two-to six-fold by addition of the appropriate modifier and selecting the optimum working conditions. The proposed methods for Se determination in environmental samples, even those containing high chloride concentrations, are very promising and have been applied to some certified samples.