Abstract
The reaction of mercury(II) with 3-(2,4-dihydroxyphen-1-ylazo)-1,2,4-triazole (HL1), 3-(2-hydroxy-5-methylphen-1-ylazo)-1,2,4-triazole (HL2), 3-(2-hydroxy-5-ethoxycarbonylphen-1-ylazo)-1,2,4-triazole (HL3), 3-(2-hydroxy-5-acetylphen-1-ylazo)-1,2,4-triazole (HL4), 3-(2-hydroxy-5-formylphen-1-ylazo)-1,2,4-triazole (HL5), and 3-(2-hydroxy-5-bromophen-1-ylazo)-1,2,4-triazole (HL6) was studied. A new, direct, and simple procedure was suggested for the spectrophotometric determination of mercury(II) based on its complexation reaction with HL1-HL6. The best reagent was found to be HL3 due to its high sensitivity and selectivity. In aqueous media of pH 9.0 containing 40 vol. % of methanol, Hg(II) reacts with HL3 to form a 1:2 (Hg(II) ยท HL3) complex having a sensitive absorption peak at 490 nm with the molar extinction coefficient of 3.31 ร 104 L molโ1 cmโ1 using 4 ร 10โ4 M of the reagent. Beerโs law is obeyed over the range from 0.00 ยตg mLโ1 to 12.04 ยตg mLโ1 of mercury(II). The proposed method was applied in the determination of mercury(II) in tap water, seawater and synthetic seawater samples, without the need of prior treatment, with satisfactory results.