TY  - JOUR
AU  - Vojic, MP
AU  - Popović, Gordana V.
AU  - Sladić, Dušan
AU  - Pfendt, Lidija B.
PY  - 2005
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/687
AB  - The acid-base equilibria of a diprotic, slightly hydrosoluble base ketoconazole were studied in homogeneous and heterogeneous water systems. The determinations were performed at 25 degreesC at a constant ionic strength of 0.1 M (NaCl). The acidity constant K,,, was determined by potentiometric (pK(a1) 3.20) and spectrophotometric (pK(al) 3.26) methods. A pK(a2) constant of 6.10 was obtained based on the equilibrium constants pK(s0) 4.84 and pK(s1) -1.26, determined in a heterogeneous ketoconazole system. The obtained values of the constants served to calculate the solubility and the distribution of the equilibrium forms of ketoconazole as a function of pH. On the basis of the distribution of the equilibrium forms of ketoconazole, a spectrophotometric method for the determination of its content in commercial tablets was developed. The determinations were performed at 225 nm in 0.1 M HCl. The method is simple and rapid and enables the direct spectrophotometric determination of the content of ketoconazole without previous isolation.
AB  - Proučene su kiselinsko-bazne ravnoteže u homogenom i heterogenom vodenom sistemu ketokonazola, diprotične teško rastvorne baze. Određivanja su vršena na temperaturi 25ºC i pri konstantnoj jonskoj sili 0,1M(NaCl). Kiselinska konstantaKa1 određena je potenciometrijski (pKa1 3,20) i spektrofotometrijski (pKa1 3,26). Konstanta pKa2 6,10 izračunata je iz ravnotežnih konstanti određenih u heterogenom sistemu: pKs0 4,84 i pKs1 -1,26. Na osnovu dobijenih vrednosti za konstante izračunata je rastvorljivost i raspodela ravnotežnih oblika ketokonazola u funkciji pH. Na bazi raspodele ravnotežnih oblika ketokonazola predložena je spektrofotometrijska metoda za njegovo određivanje u komercijalnim tabletama. Određivanja su vršena na talasnoj dužini 225 nm u 0,1M HCl.Metoda je jednostavna i brza, i omogućava direktno spektrofotometrijsko određivanje ketokonazola, bez prethodnog izolovanja.
PB  - Serbian Chemical Soc, Belgrade
T2  - Journal of the Serbian Chemical Society
T1  - Protolytic equilibria in homogeneous and heterogeneous systems of ketoconazole and its direct spectrophotometric determination in tablets
T1  - Protolitičke ravnoteže u homogenom i heterogenom sistemu ketokonazola i njegovo direktno spektrofotometrijsko određivanje u tabletama
VL  - 70
IS  - 1
SP  - 67
EP  - 78
DO  - 10.2298/JSC0501067V
ER  - 

@article{
author = "Vojic, MP and Popović, Gordana V. and Sladić, Dušan and Pfendt, Lidija B.",
year = "2005",
abstract = "The acid-base equilibria of a diprotic, slightly hydrosoluble base ketoconazole were studied in homogeneous and heterogeneous water systems. The determinations were performed at 25 degreesC at a constant ionic strength of 0.1 M (NaCl). The acidity constant K,,, was determined by potentiometric (pK(a1) 3.20) and spectrophotometric (pK(al) 3.26) methods. A pK(a2) constant of 6.10 was obtained based on the equilibrium constants pK(s0) 4.84 and pK(s1) -1.26, determined in a heterogeneous ketoconazole system. The obtained values of the constants served to calculate the solubility and the distribution of the equilibrium forms of ketoconazole as a function of pH. On the basis of the distribution of the equilibrium forms of ketoconazole, a spectrophotometric method for the determination of its content in commercial tablets was developed. The determinations were performed at 225 nm in 0.1 M HCl. The method is simple and rapid and enables the direct spectrophotometric determination of the content of ketoconazole without previous isolation., Proučene su kiselinsko-bazne ravnoteže u homogenom i heterogenom vodenom sistemu ketokonazola, diprotične teško rastvorne baze. Određivanja su vršena na temperaturi 25ºC i pri konstantnoj jonskoj sili 0,1M(NaCl). Kiselinska konstantaKa1 određena je potenciometrijski (pKa1 3,20) i spektrofotometrijski (pKa1 3,26). Konstanta pKa2 6,10 izračunata je iz ravnotežnih konstanti određenih u heterogenom sistemu: pKs0 4,84 i pKs1 -1,26. Na osnovu dobijenih vrednosti za konstante izračunata je rastvorljivost i raspodela ravnotežnih oblika ketokonazola u funkciji pH. Na bazi raspodele ravnotežnih oblika ketokonazola predložena je spektrofotometrijska metoda za njegovo određivanje u komercijalnim tabletama. Određivanja su vršena na talasnoj dužini 225 nm u 0,1M HCl.Metoda je jednostavna i brza, i omogućava direktno spektrofotometrijsko određivanje ketokonazola, bez prethodnog izolovanja.",
publisher = "Serbian Chemical Soc, Belgrade",
journal = "Journal of the Serbian Chemical Society",
title = "Protolytic equilibria in homogeneous and heterogeneous systems of ketoconazole and its direct spectrophotometric determination in tablets, Protolitičke ravnoteže u homogenom i heterogenom sistemu ketokonazola i njegovo direktno spektrofotometrijsko određivanje u tabletama",
volume = "70",
number = "1",
pages = "67-78",
doi = "10.2298/JSC0501067V"
}

Vojic, M., Popović, G. V., Sladić, D.,& Pfendt, L. B.. (2005). Protolytic equilibria in homogeneous and heterogeneous systems of ketoconazole and its direct spectrophotometric determination in tablets. in Journal of the Serbian Chemical Society
Serbian Chemical Soc, Belgrade., 70(1), 67-78.
https://doi.org/10.2298/JSC0501067V

Vojic M, Popović GV, Sladić D, Pfendt LB. Protolytic equilibria in homogeneous and heterogeneous systems of ketoconazole and its direct spectrophotometric determination in tablets. in Journal of the Serbian Chemical Society. 2005;70(1):67-78.
doi:10.2298/JSC0501067V .

Vojic, MP, Popović, Gordana V., Sladić, Dušan, Pfendt, Lidija B., "Protolytic equilibria in homogeneous and heterogeneous systems of ketoconazole and its direct spectrophotometric determination in tablets" in Journal of the Serbian Chemical Society, 70, no. 1 (2005):67-78,
https://doi.org/10.2298/JSC0501067V . .