A Selective Flow-Rate Independent Flow Injection Analysis Technique: Combination of a Single Bead String Reactor with Rapid Scan Square-Wave Voltammetry

The response of a flow injection analysis with an electrochemical detector was made independent of the flow rate by using a singe bead string reactor tube (SBSR) and by operating the detector in the rapid-scan square-wave voltammetric mode. The SBSR reduced the flow-rate dependence of the maximum concentrations of the sample zone to 10% and the square-wave voltammetric peak height was virtually independent of the flow rate. The voltage scan was triggered at the point of the maximum concentration of the sample zone. The point was detected by monitoring the ECD current at a constant potential. The operation was controlled by a personal computer. The detection limits for [Fe(CN)6]4- and dopamine were ca. 0.6nmol (=2×10-5mol dm-3×29mm3). The use of square-wave voltammetry allowed for the simultaneous determination of more than one component.