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Journal of Materials
Volume 2013 (2013), Article ID 897343, 7 pages
Research Article

Complex Formation in a Liquid-Liquid Extraction System Containing Cobalt(II), 4-(2-Pyridylazo)resorcinol, and Nitron

1Department of Chemistry and Biochemistry, Medical University Plovdiv, 15A Vassil Aprilov Boulevard, 4002 Plovdiv, Bulgaria
2Department of General and Inorganic Chemistry, University of Plovdiv “Paisii Khilendarski”, 24 Tsar Assen Street, 4000 Plovdiv, Bulgaria

Received 12 December 2012; Revised 23 February 2013; Accepted 24 February 2013

Academic Editor: Concepción López

Copyright © 2013 Petya Vassileva Racheva et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Complex formation and liquid-liquid extraction were studied in a system containing cobalt(II), 4-(2-pyridylazo)resorcinol (PAR), 1,4-diphenyl-3-(phenylamino)-1H-1,2,4-triazole (Nitron, Nt), water, and chloroform. The effect of some experimental parameters (pH, shaking time, concentration of PAR, and concentration of Nt) was systematically investigated, and the optimum conditions for cobalt extraction as an ion-association complex, (NtH+)[Co3+(PAR)2], were found. The following key equilibrium constants were calculated: constant of association , constant of distribution , and constant of extraction . Beer’s law was obeyed for Co concentrations up to 1.7 μg mL−1 with a molar absorptivity of L mol−1 cm−1 at  nm. Some additional characteristics, such as limit of detection, limit of quantification, and Sandell’s sensitivity, were estimated as well.