AMPEROMETRIC AND VOLTAMMETRIC DETECTION IN BATCH INJECTION-ANALYSIS

Batch injection analysis (BIA) enables the investigation of electrode reactions using extremely small volumes of analyte solution of 100 mu L. The potentialities of amperometric and voltammetric detection have been examined by studying the oxidation of ferrocyanide and ascorbic acid at platinum electrodes and using sample volumes between 10 and 100 mu L. The electrolysis efficiency as a function of injected volume has been addressed. Consecutive injections during a slow linear potential sweep permit the registering of a point-by-point pseudo-steady-state voltammetric curve and allow the measurement of thermodynamic and kinetic parameters as well as the determination of concentration. Cyclic voltammetry during or after injection can aid in mechanistic studies. The combination of BIA and square-wave voltammetry Leads to a continuous voltammetric profile from a single injection using 100 mu L: calibration plots show a factor of 4 sensitivity increase relative to fixed-potential amperometric detection.