DETERMINATION OF Zn(II) IN DRINKING WATER USING SEQUENTIAL INJECTION-VALVE MIXING WITH ALIZARIN RED S AS COMPLEXING AGENT

Abstract

The typical method for determination of Zn(II) in drinking water is atomic absorption spectrophotometry. However, this method requires a large amount of sample solution, reagent (nitric acid), and also time-consuming. Therefore, in this study, Sequential Injection-Valve Mixing (SI-VM) with RGB Detector at 520 nm by employing Alizarin Red S (ARS) as the complexing agent was developed for the determination of Zn(II). The optimum conditions for the complex formation of Zn-ARS are as follows: pH 4.5, ARS concentration of 5 x10 -5 M, ARS volume of 150 µL, a sample volume of 50 µL, the reaction time of 8s, and flow rate of the reaction products toward detector is 50 µL/s. This method is successfully applied to the determination of Zn(II) in drinking water with a detection limit of 5.9 µg/L (ppb). High sensitivity, less reagent and sample consumptions (200 µL), and high sample throughput (100 sample/h) can be attributed to the advantages of the proposed method.