EFFECT OF ORGANIC-SOLVENTS AND MOLECULAR GASES ON POLYATOMIC ION INTERFERENCES IN INDUCTIVELY COUPLED PLASMA MASS-SPECTROMETRY

The introduction of an organic solvent (ca. 10% propan-2-ol in water) or a molecular gas (<5% O2 or N2) into the central channel of the inductively coupled plasma has been shown to cause dramatic reductions in signals due to the polyatomic ions ArCI + , ArAr+ and CICI+, with corresponding increases in the ln+ : XY + ratios using inductively coupled plasma mass spectrometry (ICP-MS). Some evidence for the competitive formation of species such as ArC+, ArN+ and ArO + , or CCI+, NCI + and OCI+ in preference to the other interfering ions, was observed, depending on the method employed. The use of N2 at a flow-rate of 0.03 | min 1 doped into the central channel is recommended for the minimisation of ArCI+ interference in analysis by ICP-MS.