Spectrophotometric determination of mercury in water samples using 2,4-dihydroxyacetophenone acetoylhydrazone

A very simple, highly selective, direct and non-extractive spectrophotometric method for the determination of trace amounts of mercury(II) is developed using newly synthesized 2,4-dihydroxyacetophenone acetoylhydrazone (DAAH). The reagent reacts with mercury(II) in a slightly acidic medium (pH 6.5, sodium acetate-acetic acid buffer) to form yellow coloured 1 : 1 (M : L) complex. The colour reaction is instantaneous and absorbance values remain constant for 3 h. The molar absorptivity and Sandell's sensitivity of DAAH method are found to be 2.5 x 10(4) L mol(-1) cm(-1) and 0.080 mu g cm(-2) of mercury(II) respectively. The linear calibration graphs were obtained for 1.0-9.0 mu g/mL of mercury(II). The detection limit and relative standard deviation are found to be 0.0782 mu g/mL and 2.60% respectively. The method is successfully applied to a number of water samples (potable and polluted) containing mercury(II). The results of the proposed method in the analysis of water samples are comparable with those obtained by dithizone method and were found to be in good agreement.