Reaction of mercury(II) and xylenol orange—I: Effect of the buffering media

Abstract

The influence of the buffering medium on the reaction of Hg(II) with Xylenol Orange has been studied. Amine-type compounds are complexed by Hg(II)/Xylenol Orange with a sharp hyperchromic effect on the reagent itself, at 590 nm, but complex formation of Hg(II)/Xylenol Orange in non-amine-type buffer, such as citric acid-phosphate, gives a hypochromic effect on Xylenol Orange at 580 nm. Hg(II) is determined at pH 7.5 in two ranges of concentration, 2–9 ppm in citrate buffer, measured at 580 nm (ϵ = 2.50 × 10 4), and 6–11 ppm in hexamine buffer, at 590 nm (ϵ = 4.18 × 10 4).