The use of silver solid amalgam electrode for voltammetric and amperometric determination of nitroquinolines

Abstract

Solid amalgam electrodes represent a suitable alternative to mercury electrodes due to their similar electrochemical properties and non-toxicity of the amalgam material. Nitro derivatives of quinoline have been proven to be genotoxic, thus their presence in environmental samples is a legitimate cause for concern. In this contribution, meniscus modified silver solid amalgam electrode (m-AgSAE) was employed for the batch voltammetric determination and amperometric determination in connection with flow injection analysis of 5-nitroquinoline and 6-nitroquinoline (5-NQ, 6-NQ). Their electrochemical behavior was characterized by cyclic voltammetry, for their determination direct current voltammetry and differential pulse voltammetry were used. Linear calibration curves in the concentration range of 2 × 10 −7 to 1 × 10 −4 mol L −1 were obtained. These results are comparable with results obtained for polarographic determination of the same substances using mercury electrodes. Further, the meniscus modified silver solid amalgam electrode was employed in amperometric detection cell in “wall jet” arrangement for determination of 5-NQ in flow injection analysis. Under optimized conditions (run buffer 0.05 mol L −1 borate buffer, pH 9.0; flow rate 4 mL min −1; detection potential −1.6 V; injection volume 0.1 mL), the limit of quantitation of ∼4 × 10 −6 mol L −1 was achieved. The repeatability of the detector response is satisfactory (relative standard deviation ∼2.15% for c(5-NQ) = 1 × 10 −4 mol L −1). Practical applicability of the method was verified for the determination of micromolar concentrations of 5-NQ in drinking and river water model samples.