Modification of capillaries coupled to micro-flow nebulizers: a new strategy for on-line interference removal in inductively coupled plasma mass spectrometry

The application of interference removal within modified silica capillaries for the introduction of liquid samples by a micro-flow nebulizer into an in ductively coupled plasma quadrupole mass spectrometer is described using th e example of Rh-103 and its mass interferences resulting from Cu-63 (ArCu+) , Rb-87 (RbO+), Sr-87 (SrO+) and Pb-206 (Pb2+), A strong cation exchanger w as covalently bound to the capillary surface and its ability to interact wi th cations in aqueous solution was investigated. At pH 7.0 the interfering elements can be selectively adsorbed within the capillaries without hamperi ng the elution of Rh. The capillaries are easily regenerated by flushing wi th 10(-3) M hydrochloric acid in order to exchange retained cations for pro tons, Calibrations show no significant difference between the absence and p resence of interfering elements, so the detection limit for Rh of 6.0 ng l( -1) (3 sigma) is not influenced by adding up to a 100-fold excess of interf erents. The method developed is compared with a mathematical correction mod el for inductively coupled plasma mass spectrometry using the example of Rh determination in particulate car exhaust fumes and the results obtained ar e discussed. Copyright (C) 2000 John Wiley & Sons, Ltd.