SPECTROPHOTOMETRIC DETERMINATION OF MICROGRAM QUANTITIES OF Hg (II) USING THE REACTION INVOLVING POTASSIUM HEXACYANOFERRATE AND DMF

摘要

The reaction involving Potassium hexacyanoferrate (II) and the solvent DMF is spectrophotometrically monitored in the presence of buffer solution of pH 3. The addition of Hg(II) catalyzed the reaction which resulted in the development of a spectrophotometric method for the determination of Hg(II) ion in microgram quantities .The interaction between the reactants gave an orange red colored species in the pH range 1-6. The maximum absorption was observed in a buffer solution of pH 3 at the wavelength of maximum absorbance at 410 nm. The effect of time, various organic solvents on the maximum color development were studied and observed that 30 minutes time after mixing the components and the DMF solvent are found to be the most suitable. The effect of DMF solvent on the intensity of color indicated that a 40% v/v DMF used in the method is optimal. Beer's law for the spectrophotometric determination of Hg (II) was obeyed in the range 0.2μg/ ml to 1.6μg/ ml (20ng/ ml to 160ng/ ml). The molar absorptivity and Sandell sensitivity are calculated as 8.0 x 10 4 lit.mol -1 .cm -1 and 0.002507 μg/ ml respectively. The effect of various diverse ions in the determination is studied. The proposed procedure for Hg (II) determination finally agreed favorably well with the kinetic method developed.