THEORETICAL-ANALYSIS OF PROBE DYNAMICS IN FLOW-INJECTION MEMBRANE INTRODUCTION MASS-SPECTROMETRY

The dynamic response of the membrane probe in flow injection/membrane introduction mass spectrometry has been studied theoretically. A mathematical model is formulated to obtain analyte concentration profiles in the flow chamber and inside the membrane and to calculate the analyte flux across the membrane. For ideal input perturbations such as block and step inputs, analytical solutions are provided; for nonlinear input perturbations an efficient and robust computational procedure for obtaining numerical solutions is presented to account for mixing of the analyte sample in the flow conduit before entering the flow chamber. The effect of some system parameters and operational variables on the dynamic behavior of the probe is investigated. This information should help in the design of new membrane probes and in the selection of new membranes.