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Abstrakty
The RP-TLC method was used to determine the dissociation constant of chrysin (5,7-dihydroxyflavone) in methanol-aqueous (1:1 v/v) solutions. In this method the pK value was quantified on the basis of retention data and a retention model. The accuracy of determining the model parameters was analysed using the following statistical criteria: the sum of the squared differences between the experimental and theoretical data, approximation of standard deviation, and the Fisher test. Besides, in this work the potentiometric method was used. Investigations were carried out at ionic strength I=0.1 at T= 298 K. The dissociation constant were determined using the Rossotti method as well as the numerical method based on the procedures of non-linear curve fitting using Microsoft Excel Solver and the user-defined function. It has been found that the differences in the evaluated pK values were relatively small and did not exceed 1.2%.
Czasopismo
Rocznik
Tom
Strony
41--44
Opis fizyczny
Bibliogr. 18 poz., rys., tab.
Twórcy
autor
autor
autor
- Department of Inorganic and Analytical Chemistry, Rzeszów University of Technology, bpapciak@prz.edu.pl
Bibliografia
- 1. Benavente-Garcia, O., Castillo, J., Marin, F. R., Ortuno A. & Del Rio J. A. (1997). Uses and Properties of Citrus Flavonoids., J. Agric. Food Chem. 45(12), 4505 - 4515.
- 2. Di Carlo, G., Mascolo, N., Izzo A. A. & Capasso F. (1999) Flavonoids: old and new aspects of a class of natural therapeutic drugs. Life Sci. 65(4), 337 - 353.
- 3. Harborne J. B. & Mabry T. J. (1982). The Flavonoids Advances in Research. Chapman and Hall, London.
- 4. Cody, V., Middleton E. & Harborne J. B. (1986). Plant Flavonoids in Biology and Medicine: Biochemical, Pharmacological and Structure-Activity relationships. Alan R. Liss, New York.
- 5. Cody, V., Middleton, E., Harborne J. B. & Beretz A. (1988). Plant flavonoids in biology and medicine II: Biochemical, Cellular and Medicinal Properties. Alan R. Liss, New York,.
- 6. Pusz J. & Nitka B. (1997). Synthesis and Physicochemical Properties of the Complexes of Co(III), Ni(III) and Cu(III) with Chrysin. Microchem. J. 56, 373 - 381.
- 7. Pusz J. & Nitka B. (1996). Synthesis and physicochemical properties of the compounds of iron(III), cadmium(II) and lead(II) ions with chrysin. Zeszyty Naukowe Politechniki Rzeszowskiej. 14, 55 - 73, (in Polish).
- 8. Barcella, A. L., Grunwald, E., Marshall H. P. & Purlee E. L. (1955). The potentiometric measurement of acid dissociation constants and pH in the system methanol-water. pKA values for carboxylic acids and anilinium ions. J. Org. Chem. 20, 747-762.
- 9. Sheldovsky T. & Kay R. L. (1956). The ionization constant of acetic acid in water-methanol mixtures at 250 from conductance measurements. J. Phys. Chem. 60(2), 151 - 155.
- 10. de Ligny, C. L. (1960). The dissociation constants of some aliphatic amines in water and methanol-water mixtures at 25°C. Recl. Trav. Chim. Pays-Bas. 60, 731 - 746.
- 11. de Ligny, C. L., Loriaux H. & Ruiter A. (1961). The application of Hammett's acidity function Ho to solutions in methanol-water mixtures. Recl. Trav. Chim. Pays-Bas. 80, 725 - 739.
- 12. Chatten, L. G. & Harris, L. E. (1962) Relationship between pKb(H2O) of organic compounds and E/2 values in several nonaqueous solvents. Anal. Chem. 34, 1495 - 1501.
- 13. Lide, D. R. (1997 - 1998). Handbook of Chemistry and Physics (78th ed.) (pp. 3 - 78). CRC Press, New York.
- 14. Fried, B. & Sherma, J. (1999) Thin-Layer Chromatography (Chromatographic Science, V. 81) (4th ed.). Marcel Dekker, USA.
- 15. Espinoza, S., Bosch E. & Roses M. (2002). Retention of ionizable compounds in high-performance liquid chromatography. IX. Modelling retention in reversed-phase liquid chromatography as a function of pH and solvent composition with acetonitryle-water mobile phases. J. Chromatogr. A. 947, 47 - 58.
- 16. Fletcher, R. (1971). A modified Marquardt sub-routine for nonlinear least-squares. AERE-R6799-Harwell - England.
- 17. Rossotti, H. (1983). The ions equilibria. PWN, Warsaw, Poland, (in Polish).
- 18. Maleki, N., Haghighi B. & Safavi A. (1999). Evaluation of Formation Constants, Molar Absorptivities of Metal Complexes, and Protonation Constants of Acids by Nonlinear Curve Fitting Using Microsoft Excel Solver and User-Defined Function, Microchemical Journal. 62, 229 - 236.
Typ dokumentu
Bibliografia
Identyfikator YADDA
bwmeta1.element.baztech-article-BPS2-0047-0040