Screen printed electrode-flow stripping voltammetry for inorganic analysis

The use of a commercial wall-jet cell for alumina-based screen printed sensors has regained new life to flow injection techniques in voltammetry. Of the many theoretical advantages of flow injection stripping, the possibility of using external calibration is of primary importance to the applied analytical chemist, since higher throughput is gained if compared to the commonly-used standard addition methodology. Adversely, external calibration in voltammetry heavily relies on the instrumental conditions, and needs careful optimization. Flow injection voltammetry with wall-jet cells for SPE has been investigated using the new 4330 voltammetric instrument from Amel Instruments, Italy. The instrumental configuration has been optimized both in continuous flow (CF-SV) operations, where bubble formation during sample exchange must be minimized, and in flow-injection (FI-SV), where the analytical reproducibility is dependent on the peak shape. A new voltammetric software (VApeak2) has also been implemented for FIA and external calibration operations. Reproducibility was found to be very good under typical analytical conditions, with excellent calibration linearity, and limits of detection around 0.6 μg/L for Pb and 0.3 μg/L for Cd. Quantitation of Pb and Cd on real samples has been also carried out via external calibration, giving excellent results, particularly at low concentrations.