Intelligent flow-injection—inductively coupled plasma system for matrix matching

Water samples with variable salinity are analysed by a flow-injection—inductively coupled plasma (ICP) system. The sampling zone approach is used to level the sample and standard saline contents in order to compensate for matrix effects. Calibration graphs for Ca, Mg, Al, Fe, P and Si at three different sodium concentrations are obtained. The sample and standard salinity matching is done automatically by processing the sample sodium signal from the ICP with a microcomputer and adding a suitable amount of sodium. The decision process consists in choosing the appropriate standard solution and adjusting the commutation delay for the sampling zone, using a previously determined time—concentration curve. Sodium interference is minimized, allowing the analysis of water samples with a saline matrix up to 2.5% (w/v) NaCl. The proposed method is suitable for 60 samples h^?1.