Effect of the sample introduction system in ICP-MS on the formation of both oxygenated polyatomic and doubly charged ions

The effect on the formation of both oxygenated polyatomic and doubly charge d ions in inductively coupled plasma mass spectrometry (ICP-MS) has been ev aluated for sample introduction with three different injection devices. An ultrasonic nebulizer (USN) equipped with an efficient membrane desolvator, in addition to a usual desolvation module incorporating a heater and conden ser, in comparison with both a concentric flow pneumatic nebulizer (PN) and the USN above without the mentioned additional membrane-desolvating module , offers the advantage of reducing markedly the relative abundance of both oxygenated polyatomic and doubly charged ions, thus leading to an overall i mprovement in the detection limits for the elements affected by their inter ferences. At the same time, detection limits for analytes unplagued by over lapping hem these undesired ions remain unaffected since the additional mem brane desolvator causes little or no sacrifice in the analyte signals, exce pt for typically volatile elements, such as Se and Hg, whose detection limi ts worsen significantly.