Flow injection analysis of the insecticide imidacloprid in water samples with photochemically induced fluorescence detection

The voltammetric behavior of Vitamin C (L-ascorbic acid) at carbon paste electrodes and electrodes modified with aza macrocycles have been studied. The use of zinc complexes, formed in situ at the electrode surface reduced the overpotential for the oxidation of ascorbic acid by about 200mV and enhanced the peak currents. Linearity was observed over the range of 0.6-500µg/cm3 with a detection limit of 0.1µg/cm3 by differential pulse voltammetry. The modified electrode was used for the determination of Vitamin C in multivitaminmultimineral pharmaceutical preparations, fruit juices and wine samples.