Sono-Adsorptive Stripping Voltammetry: Its Application to the Analysis of Metals and Organic Compounds in Aqueous Media

Abstract

The effect of applying ultrasound during the preconcentration step of the adsorptive stripping voltammetry (AdSV) analysis of vanadium, nickel and riboflavin is presented. First, the sono-AdSV determination of vanadium(V) was achieved by interfacial accumulation of its catechol complex under ultrasound applied from an ultrasonic probe opposite a mercury-coated copper electrode. Ultrasound was found to increase the speed at which the complex was deposited onto the mercury surface in comparison with silent conditions. Similar analytical performances to those described in the literature were obtained for shorter preconcentration times under ultrasound. Second, the effect of ultrasound on the AdSV analysis of Ni2+ was studied using a mercury film plated in situ on a glassy carbon electrode. Dimethylglyoxime was used as the complexing agent. The loss of mercury due to sonication is shown to decrease the sensitivity of the method. Third, the sono-AdSV analysis of an organic compound, riboflavin, was investigated. Accumulation of riboflavin was conducted both in a preplated mercury film electrode and on a glassy carbon substrate. Faster rates of adsorption were observed for riboflavin under the presence of ultrasound. In addition the AdSV analysis of riboflavin also benefits from surface activation of the glassy carbon electrode due to cleaning of its surface by the use of ultrasound. In this respect, partial removal of lumichrome, a less adsorbing species than riboflavin under these conditions and a product of riboflavin photolysis, has been observed under sonication.