Simultaneous sample preconcentration and matrix removal using field-flow fractionation coupled to inductively coupled plasma mass spectrometry

An on-channel sample pre concentration-matrix removal arrangement, based on coupling field-flow fractionation (FFF) to inductively coupled plasma mass spectrometry (ICP-MS), has been constructed for on-line sample pretreatmen t ICP-MS trace element determination. A commercial FFF system is modified t o incorporate an on-channel preconcentration procedure allowing injection o f up to 50 ml of sample, which could be preconcentrated by 50-1400 fold. A high molecular weight complexing agent added to the sample forms strong com plexes with the measured trace analytes but not with the sample matrix. Whe n the sample-complexing agent mixture is introduced to the FFF unit, the un complexed matrix element is removed by permeation through a membrane that s eparates the FFF sample compartment. The trace analytes remain in the FFF c hannel, because their high molecular weight complexes do not permeate throu gh the membrane. Pre concentration and matrix elimination occur simultaneou sly. The matrix-free, preconcentrated sample is introduced directly to the ICP-MS nebulizer. The method was tested using 10-ml sample aliquots that co ntain As, Cd, Cu, Mo, Pb, Re, Sn, Te, TI, Y, Zn and Zr analytes and 5000 mg l(-1) Ca or Na matrices and ethylene imine polymer complexing agent. Coppe r and Re isotopic ratio values in reference standards also were determined after preconcentration and matrix element removal. (C) 2001 Elsevier Scienc e B.V. All rights reserved.