OPTIMIZATION OF THE EXTRACTION CONDITIONS FOR THE Hg²⁺ - DITHIZONE COMPLEX IN CHLOROFORM AND ITS DETERMINATION BY UV-VIS SPECTROPHOTOMETRY
DOI:
https://doi.org/10.59957/jctm.v61.i1.2026.8Keywords:
mercury determination, UV-Vis, Hg2 - dithizone complex, liquid-liquid extraction, optimization.Abstract
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.
References
S. Covelli, J. Faganeli, M. Horvat, A. Brambati, Mercury contamination of coastal sediments as the result of long-term cinnabar mining activity (Gulf of Trieste, northern Adriatic Sea), Appl. Geochem., 16, 2001, 541–558.
W.F. Fitzgerald, C.H. Lamborg, C.R. Hammerschmidt, Chem. Rev., 107(2), 2007, 641–662.
U. Kwasigroch, K. Łukawska-Matuszewska, A. Jędruch, O. Brocławik, M. Bełdowska, Mar. Environ. Res., 191, 2023, 106132.
D. O'Connor, D. Hou, Y.S. Ok, J. Mulder, L. Duan, Q. Wu, S. Wang, F.M.G. Tack, J. Rinklebe, Mercury speciation, transformation, and transportation in soils, atmospheric flux, and implications for risk management: A critical review, Environ. Int., 126, 2019, 747–761.
UNEP, Global Mercury Assessment 2018, United Nations Environment Programme, Chemicals and Health Branch, Geneva, 2019.
S. Valtchev, L. Bidzhova, A. Toteva, S.V. Georgiev, S. Kolev, Overview of mercury occurrence in Bulgarian groundwater: Preliminary data, Rev. Bulg. Geol. Soc., 85(3), 2024, 249–252.
E. Mladenova, I. Dakova, D. Tsalev, I. Karadjova, Mercury determination and speciation analysis in surface waters, Open Chem., 10(4), 2012, 1175–1182.
M. Dinkova-Kostova, M. Stancheva, K. Peycheva, Heavy metals in water, sediments and marine fishes from the Bulgarian Black Sea, in: Proceedings of EMECS-10, Monaco, 2017.
K. Peycheva, L. Makedonski, S. Georgieva, M. Stancheva, Assessment of mercury content in fish tissues from Bulgarian lakes and the Black Sea, Ecol. Safety, 9(1), 2015, 43–48.
O. Vitov, I. Marinova, Natural potential sources for mercury pollution in Bulgaria, J. Min. Metall., 50(2), 2014, 123–132.
I.J. Kostova, J.C. Hower, M. Mastalerz, S.V. Vassilev, Mercury capture by selected Bulgarian fly ashes: Influence of coal rank and fly ash carbon pore structure on capture efficiency, Appl. Geochem., 26(1), 2011, 18–27.
FAO/WHO, Measurement Uncertainty – CXG 54-2004, 2023.
J. Zhang, W. Zhang, Y. Jin, Sensitive determination of trace mercury by UV-visible diffuse reflectance spectroscopy after complexation and membrane filtration-enrichment, Spectrochim. Acta A, 87, 2012, 265–270.
A. Afkhami, T. Madrakian, S.J. Sabounchei, Cloud point extraction and spectrophotometric determination of trace mercury(II) using dithizone, J. Hazard. Mater., 174(1–3), 2010, 451–456.
R.W. Christensen, R.M. Madsen, Determination of mercury(II) concentration in water using dithizone, Bachelor’s Thesis, Aarhus University, Department of Chemistry, Denmark, 2019.
G. Svehla, Vogel’s Qualitative Inorganic Analysis, 7th ed., Longman, 1996
M.J. Ahmed, M.S. Alam, A rapid spectrophotometric method for the determination of mercury in environmental, biological, soil and plant samples using diphenylthiocarbazone, Spectroscopy, 17, 2003, 45–52.
C.T. Elly, Dithizone procedure for mercury analysis, J. Water Pollut. Control Fed., 45(5), 1973, 940–945.
T. Braun, A.B. Farag, Plasticized open-cell polyurethane foam as a universal matrix for organic reagents in trace element preconcentration: Part II. Collection of mercury traces on dithizone and diethyldithiocarbamate foams, Anal. Chim. Acta, 71(1), 1974, 133–140.
W. Stumm, J.J. Morgan, Aquatic Chemistry: Chemical Equilibria and Rates in Natural Waters, 3rd ed., John Wiley & Sons, New York, 1996.
G.D. Christian, Analytical Chemistry, 6th ed., Wiley, New York, 2004.
Z. Marczenko, Separation and Spectrophotometric Determination of Elements, Ellis Horwood, 1986, 48–52.
E.B. Sandell, Colorimetric Determination of Traces of Metals, 3rd ed., Interscience, New York, 1959.
D.A. Skoog, F.J. Holler, S.R. Crouch, Principles of Instrumental Analysis, 7th ed., Brooks Cole, Boston, 2017.
European Commission, Technical Guideline on the Evaluation of Extraction Efficiency of Residue Analytical Methods, SANTE/2017/10632, Rev. 5, 11 May 2023
EPA Method 3500C, Organic extraction and sample preparation, Revision 3, February 2007
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