OPTIMIZATION OF THE EXTRACTION CONDITIONS FOR THE Hg²⁺ - DITHIZONE COMPLEX IN CHLOROFORM AND ITS DETERMINATION BY UV-VIS SPECTROPHOTOMETRY

This study aimed to optimize a UV - Vis spectrophotometric method for determining mercury based on its extraction with dithizone in chloroform. In the present work, the effects of pH, reagent concentration, stoichiometry of the complex were investigated. In addition, the sensitivity of the method was determined by calculating the molar absorbance, assessing the linearity and shaking time. Optimal conditions were established at pH ≈ 1.0 ± 0.1, using 4.00 mL of 5.00 mg L⁻¹ dithizone and 1.00 min shaking. Under these parameters, the method showed stable absorbance and reproducible results. The calibration was linear within 0.80 - 1.10 mg L⁻¹ Hg, and recovery tests yielded 71 - 74 % for spiked tap and deionized water samples. The optimized procedure provides reliable preliminary mercury determination and can be further adapted for complex matrices such as sediment, soil, or coal after microwave digestion.