Naked-eye detection of trace arsenic(V) in aqueous media using molybdenum-loaded chelating resin having β-hydroxypropyl-di(β-hydroxyethyl)amino moiety

A naked-eye detection method for a trace amount of arsenic in aqueous samples has been newly developed. The proposed method is based on the formation of a hetero poly acid in a chelating resin phase. Molybdenum loaded on a chelating resin having β-hydroxypropyl-di(β-hydroxyethyl) amino moiety reacts with arsenic(V) to form the hetero poly acid, which makes the resin beads greenish blue in the presence of a reducing agent under acidic conditions. It was also found that the intensity of the color of the resin depends on the concentration of arsenic(V) in the sample solutions. Since the development of the color occurs in 20 min by heating of the mixture at 40 °C, this system can provide a simple, rapid and low-cost detection method of a trace amount of arsenic(V) in an aqueous media. The detection limit of this method is 1 × 10−6 mol dm−3. A longer preconcentration time with the same resin gave the higher sensitivity of 1 × 10−7 mol dm−3 that is comparable with that of the instrumental analysis. The present method comprises both the concentration and detection step with the same solid material, and hence it gives higher sensitivity and easier handling than the ordinary colorimetric methods using a liquid medium.