Paper-based device (PAD) for simultaneous determination of Hg(II) and Pb(II) in water samples from São Francisco River, Brazil

Abstract

Hg(II) and Pb(II) are considered potentially toxic metals (PTMs) that can be found in several ecosystems, including water systems such as lakes, rivers and groundwaters. These species are classified as human carcinogens and non-biodegradable pollutants, leading to neurological and nutritional disorders, as well as chronic diseases. Due to its relevance, several methods have been developed to determine the concentration of these PTMs; however, they require costly reagents, laborious operation and complex equipment. Herein, we present a simple-to-use and low-cost paper-based device (PAD) for Hg(II) and Pb(II) determination in natural water samples based on the colorimetric reaction between these PMTs and the dithizone colorimetric probe. The color intensity was employed as an analytical signal, through the color channels of the RGB scale. Under optimized conditions, a linear correlation of r = 0.989 and r = 0.991 and linear range of 1–20 µg/mL and 5–30 µg/mL were obtained for Hg(II) and Pb(II), respectively. After analytical optimization, the method was employed for PMTs determination using real samples from São Francisco River, Brazil. Thus, this method proved to be appropriate for Hg(II) and Pb(II) determination in natural water samples and is a easy, low-cost and straightforward alternative for the simultaneous determination of Hg(II) and Pb(II).