N'-(1-(Pyridin-2-yl)ethylidene)isonicotinohydrazide (2-ACPINH) is identified as a selective and sensitive analytical reagent for the determination of trace levels of mercury (II) in environmental samples and synthetic mixtures by spectrophotometry. 2-ACPINH reacts with mercury (II) forms greenish yellow colored 2:3 (Hg-2-ACPINH) complex at pH 5.5, in aqueous DMF. The Hg-2-ACPINH complex shows maximum absorbance at λmax 357nm. The color reaction is immediate and the absorbance remains constant for about 24h.The molar absorptivity coefficient and Sandell’s sensitivity are found to be 5.48x104 L.mol-1 cm-1 and 0.0010μg cm-2of mercury (II) respectively. The linear regression coefficient is 0.99925 and standard deviation is 0.04175. The system obeys Beer`s law in the range of 0.2-2.0 μg mL-1 of Hg (II). Large number of cations, anions and complexing agents do not interfere in this method. This method is successfully applied for the determination of mercury in a number of environmental water samples (potable and polluted), food samples and synthetic mixtures.
