TY  - JOUR
AU  - Vojić, Mirjana P.
AU  - Popović, Gordana
AU  - Sladić, Dušan
AU  - Pfendt, Lidija
PY  - 2005
UR  - https://farfar.pharmacy.bg.ac.rs/handle/123456789/659
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 25ºC at a constant ionic strength of M(NaCl). The acidity constant Ka1 was determined by potentiometric (pKa1 3.20) and spectrophotometric (pKa1 3.26) methods. A pKa2 constant of 6.10 was obtained based on the equilibrium constants pKs0 4.84 and pKs1 -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  - Srpsko hemijsko društvo, Beograd
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 = "Vojić, Mirjana P. and Popović, Gordana and Sladić, Dušan and Pfendt, Lidija",
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 25ºC at a constant ionic strength of M(NaCl). The acidity constant Ka1 was determined by potentiometric (pKa1 3.20) and spectrophotometric (pKa1 3.26) methods. A pKa2 constant of 6.10 was obtained based on the equilibrium constants pKs0 4.84 and pKs1 -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 = "Srpsko hemijsko društvo, Beograd",
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"
}

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

Vojić MP, Popović G, Sladić D, Pfendt L. 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 .

Vojić, Mirjana P., Popović, Gordana, Sladić, Dušan, Pfendt, Lidija, "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 . .

TY  - JOUR
AU  - Damjanović, Tatjana
AU  - Popović, Gordana
AU  - Verbić, Srđan
AU  - Pfendt, Lidija
PY  - 2004
UR  - https://farfar.pharmacy.bg.ac.rs/handle/123456789/504
AB  - Quantitative study of an acid hydrolysis of bromazepam, which in acidic solution simultaneously undergoes reversible 4,5-azomethine bond cleavage and protolytic reactions, was performed (t = 25degreesC). When an equilibrium is established, four species are simultaneously present in solution. Two approaches, both based on theoretically derived dependence between the absorbance (A) and the solution acidity ([H3O+]), were used to determine appropriate equilibrium constants. In the first, the least-squares method was used to fit experimentally obtained (A, [H3O+]) value pairs to a derived function. With values obtained as fitting parameters, the probability distribution for equilibrium constants was calculated with the virtual experiments performed using Monte Carlo simulations. In the second one, spectrophotometric analysis indicated an existence of two distinct pH intervals, both with three dominant species involved. Spectral data were used to calculate equilibrium constants by a linear curve fitting analysis. Values obtained for equilibrium constants from the numerical and the experimental approaches are in good accordance and were used to calculate distribution of all the species as a function of pc(H).
PB  - Canadian Science Publishing, Nrc Research Press, Ottawa
T2  - Canadian Journal of Chemistry
T1  - Study of acid hydrolysis of bromazepam
VL  - 82
IS  - 8
SP  - 1260
EP  - 1265
DO  - 10.1139/V04-091
ER  - 

@article{
author = "Damjanović, Tatjana and Popović, Gordana and Verbić, Srđan and Pfendt, Lidija",
year = "2004",
abstract = "Quantitative study of an acid hydrolysis of bromazepam, which in acidic solution simultaneously undergoes reversible 4,5-azomethine bond cleavage and protolytic reactions, was performed (t = 25degreesC). When an equilibrium is established, four species are simultaneously present in solution. Two approaches, both based on theoretically derived dependence between the absorbance (A) and the solution acidity ([H3O+]), were used to determine appropriate equilibrium constants. In the first, the least-squares method was used to fit experimentally obtained (A, [H3O+]) value pairs to a derived function. With values obtained as fitting parameters, the probability distribution for equilibrium constants was calculated with the virtual experiments performed using Monte Carlo simulations. In the second one, spectrophotometric analysis indicated an existence of two distinct pH intervals, both with three dominant species involved. Spectral data were used to calculate equilibrium constants by a linear curve fitting analysis. Values obtained for equilibrium constants from the numerical and the experimental approaches are in good accordance and were used to calculate distribution of all the species as a function of pc(H).",
publisher = "Canadian Science Publishing, Nrc Research Press, Ottawa",
journal = "Canadian Journal of Chemistry",
title = "Study of acid hydrolysis of bromazepam",
volume = "82",
number = "8",
pages = "1260-1265",
doi = "10.1139/V04-091"
}

Damjanović, T., Popović, G., Verbić, S.,& Pfendt, L.. (2004). Study of acid hydrolysis of bromazepam. in Canadian Journal of Chemistry
Canadian Science Publishing, Nrc Research Press, Ottawa., 82(8), 1260-1265.
https://doi.org/10.1139/V04-091

Damjanović T, Popović G, Verbić S, Pfendt L. Study of acid hydrolysis of bromazepam. in Canadian Journal of Chemistry. 2004;82(8):1260-1265.
doi:10.1139/V04-091 .

Damjanović, Tatjana, Popović, Gordana, Verbić, Srđan, Pfendt, Lidija, "Study of acid hydrolysis of bromazepam" in Canadian Journal of Chemistry, 82, no. 8 (2004):1260-1265,
https://doi.org/10.1139/V04-091 . .

TY  - JOUR
AU  - Pfendt, Lidija
AU  - Dražić, Branka
AU  - Popović, Gordana
AU  - Drakulić, Branko
AU  - Vitnik, Željko J.
AU  - Juranić, Ivan O.
PY  - 2003
UR  - https://farfar.pharmacy.bg.ac.rs/handle/123456789/457
AB  - For a series of seven unsaturated and seven epoxy di- and tricarboxylic acids, pK(a)(a) values were determined potentiometrically in aqueous media at 25 degreesC and an ionic strength of 0.1 M (NaCl). The thermodynamic pKaa values were correlated with the atomic charges of carboxylic group calculated by the MNDO-PM3 semiempirical MO method.
PB  - Scientific Reviews Ltd.
T2  - Journal of Chemical Research - Part S
T1  - Determination of all pK(a) values of some di- and tri-carboxylic unsaturated and epoxy acids and their polylinear correlation with the carboxylic group atomic charges
IS  - 5
SP  - 247
EP  - 248
UR  - https://hdl.handle.net/21.15107/rcub_farfar_457
ER  - 

@article{
author = "Pfendt, Lidija and Dražić, Branka and Popović, Gordana and Drakulić, Branko and Vitnik, Željko J. and Juranić, Ivan O.",
year = "2003",
abstract = "For a series of seven unsaturated and seven epoxy di- and tricarboxylic acids, pK(a)(a) values were determined potentiometrically in aqueous media at 25 degreesC and an ionic strength of 0.1 M (NaCl). The thermodynamic pKaa values were correlated with the atomic charges of carboxylic group calculated by the MNDO-PM3 semiempirical MO method.",
publisher = "Scientific Reviews Ltd.",
journal = "Journal of Chemical Research - Part S",
title = "Determination of all pK(a) values of some di- and tri-carboxylic unsaturated and epoxy acids and their polylinear correlation with the carboxylic group atomic charges",
number = "5",
pages = "247-248",
url = "https://hdl.handle.net/21.15107/rcub_farfar_457"
}

Pfendt, L., Dražić, B., Popović, G., Drakulić, B., Vitnik, Ž. J.,& Juranić, I. O.. (2003). Determination of all pK(a) values of some di- and tri-carboxylic unsaturated and epoxy acids and their polylinear correlation with the carboxylic group atomic charges. in Journal of Chemical Research - Part S
Scientific Reviews Ltd..(5), 247-248.
https://hdl.handle.net/21.15107/rcub_farfar_457

Pfendt L, Dražić B, Popović G, Drakulić B, Vitnik ŽJ, Juranić IO. Determination of all pK(a) values of some di- and tri-carboxylic unsaturated and epoxy acids and their polylinear correlation with the carboxylic group atomic charges. in Journal of Chemical Research - Part S. 2003;(5):247-248.
https://hdl.handle.net/21.15107/rcub_farfar_457 .

Pfendt, Lidija, Dražić, Branka, Popović, Gordana, Drakulić, Branko, Vitnik, Željko J., Juranić, Ivan O., "Determination of all pK(a) values of some di- and tri-carboxylic unsaturated and epoxy acids and their polylinear correlation with the carboxylic group atomic charges" in Journal of Chemical Research - Part S, no. 5 (2003):247-248,
https://hdl.handle.net/21.15107/rcub_farfar_457 .

TY  - JOUR
AU  - Popović, Gordana
AU  - Sladić, Dušan
AU  - Stefanović, Violeta M.
AU  - Pfendt, Lidija
PY  - 2003
UR  - https://farfar.pharmacy.bg.ac.rs/handle/123456789/418
AB  - Protolytic equilibria in homogeneous and heterogeneous systems of lorazepam and oxazepam, which are sparingly soluble ampholytes from the class of 1,4-benzodiazepines, were studied at 25 degreesC and ionic strength of 0.1 M. Acidity constants and equilibrium constants in a heterogeneous system were determined. On the basis of the analysis of the corresponding C-13- and H-1-NMR spectra, deprotonation site in the molecules of the investigated compounds was predicted. Finally, the correlation between chemical shifts in the H-1-NMR spectra and the acidity of the amide proton of 1,4-benzodiazepines was established.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Journal of Pharmaceutical and Biomedical Analysis
T1  - Study on protolytic equilibria of lorazepam and oxazepam by UV and NMR spectroscopy
VL  - 31
IS  - 4
SP  - 693
EP  - 699
DO  - 10.1016/S0731-7085(02)00686-6
ER  - 

@article{
author = "Popović, Gordana and Sladić, Dušan and Stefanović, Violeta M. and Pfendt, Lidija",
year = "2003",
abstract = "Protolytic equilibria in homogeneous and heterogeneous systems of lorazepam and oxazepam, which are sparingly soluble ampholytes from the class of 1,4-benzodiazepines, were studied at 25 degreesC and ionic strength of 0.1 M. Acidity constants and equilibrium constants in a heterogeneous system were determined. On the basis of the analysis of the corresponding C-13- and H-1-NMR spectra, deprotonation site in the molecules of the investigated compounds was predicted. Finally, the correlation between chemical shifts in the H-1-NMR spectra and the acidity of the amide proton of 1,4-benzodiazepines was established.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Journal of Pharmaceutical and Biomedical Analysis",
title = "Study on protolytic equilibria of lorazepam and oxazepam by UV and NMR spectroscopy",
volume = "31",
number = "4",
pages = "693-699",
doi = "10.1016/S0731-7085(02)00686-6"
}

Popović, G., Sladić, D., Stefanović, V. M.,& Pfendt, L.. (2003). Study on protolytic equilibria of lorazepam and oxazepam by UV and NMR spectroscopy. in Journal of Pharmaceutical and Biomedical Analysis
Pergamon-Elsevier Science Ltd, Oxford., 31(4), 693-699.
https://doi.org/10.1016/S0731-7085(02)00686-6

Popović G, Sladić D, Stefanović VM, Pfendt L. Study on protolytic equilibria of lorazepam and oxazepam by UV and NMR spectroscopy. in Journal of Pharmaceutical and Biomedical Analysis. 2003;31(4):693-699.
doi:10.1016/S0731-7085(02)00686-6 .

Popović, Gordana, Sladić, Dušan, Stefanović, Violeta M., Pfendt, Lidija, "Study on protolytic equilibria of lorazepam and oxazepam by UV and NMR spectroscopy" in Journal of Pharmaceutical and Biomedical Analysis, 31, no. 4 (2003):693-699,
https://doi.org/10.1016/S0731-7085(02)00686-6 . .

TY  - JOUR
AU  - Pfendt, Lidija
AU  - Popović, Gordana
AU  - Damjanović, Tatjana
AU  - Sladić, Dušan
PY  - 2002
UR  - https://farfar.pharmacy.bg.ac.rs/handle/123456789/395
AB  - The protolytic equilibria of bromazepam, an ampholyte sparingly soluble in water, in homogeneous and heterogeneous systems were studied in the pH range 0–14 at 25ºC and at ionic strength of 0.1 mol/dm3 (NaCl). On the basis of 13C-NMR spectra, the protonation site was predicted – in acidic media the pyridine nitrogen of bormazepam is protonated. The acidity constants of bromazepam were determined spectrophotometrically (pKa1 2.83 and pKa2 11.60) and potentiometrically (pKa1 2.99). In the heterogeneous system the following equilibrium constants were determined: Ks0 =[HA](pKs0 3.44), Ks1 =[H2A+]/[H3O+](pKs1 0.61), and Ks2 =[A-][H3O+](pKs2 15.04).
AB  - Proučavane su protolitičke ravnoteže bromazepama, amfolita iz klase 1,4-benzodiazepina, slabo rastvornog u vodi. Ispitivanja su vršena u homogenom i heterogenom sistemu u pH intervalu 0–14, na temperaturi 25ºC i pri jonskoj sili 0,1 mol/dm3 (NaCl). Na osnovu 13C-NMR spektara pretpostavljeno je da do protonovanja u molekulu bromazepama dolazi na piridinskom atomu azota. Kiselinske konstante određene su spektrofotometrijski (pKa1 2.83 and pKa2 11.60) i potenciometrijski (pKa1 2,99). U heterogenom sistemu određene su sledeće ravnotežne konstante Ks0 =[HA](pKs0 3.44), Ks1=[H2A+]/[H3O+](pKs1 0.61), and Ks2 =[A-][H3O+](pKs2 15.04).
PB  - Srpsko hemijsko društvo, Beograd
T2  - Journal of the Serbian Chemical Society
T1  - Protolytic equlibria of bromazepam
T1  - Protolitičke ravnoteže bromazepama
VL  - 67
IS  - 3
SP  - 187
EP  - 195
DO  - 10.2298/JSC0203187P
ER  - 

@article{
author = "Pfendt, Lidija and Popović, Gordana and Damjanović, Tatjana and Sladić, Dušan",
year = "2002",
abstract = "The protolytic equilibria of bromazepam, an ampholyte sparingly soluble in water, in homogeneous and heterogeneous systems were studied in the pH range 0–14 at 25ºC and at ionic strength of 0.1 mol/dm3 (NaCl). On the basis of 13C-NMR spectra, the protonation site was predicted – in acidic media the pyridine nitrogen of bormazepam is protonated. The acidity constants of bromazepam were determined spectrophotometrically (pKa1 2.83 and pKa2 11.60) and potentiometrically (pKa1 2.99). In the heterogeneous system the following equilibrium constants were determined: Ks0 =[HA](pKs0 3.44), Ks1 =[H2A+]/[H3O+](pKs1 0.61), and Ks2 =[A-][H3O+](pKs2 15.04)., Proučavane su protolitičke ravnoteže bromazepama, amfolita iz klase 1,4-benzodiazepina, slabo rastvornog u vodi. Ispitivanja su vršena u homogenom i heterogenom sistemu u pH intervalu 0–14, na temperaturi 25ºC i pri jonskoj sili 0,1 mol/dm3 (NaCl). Na osnovu 13C-NMR spektara pretpostavljeno je da do protonovanja u molekulu bromazepama dolazi na piridinskom atomu azota. Kiselinske konstante određene su spektrofotometrijski (pKa1 2.83 and pKa2 11.60) i potenciometrijski (pKa1 2,99). U heterogenom sistemu određene su sledeće ravnotežne konstante Ks0 =[HA](pKs0 3.44), Ks1=[H2A+]/[H3O+](pKs1 0.61), and Ks2 =[A-][H3O+](pKs2 15.04).",
publisher = "Srpsko hemijsko društvo, Beograd",
journal = "Journal of the Serbian Chemical Society",
title = "Protolytic equlibria of bromazepam, Protolitičke ravnoteže bromazepama",
volume = "67",
number = "3",
pages = "187-195",
doi = "10.2298/JSC0203187P"
}

Pfendt, L., Popović, G., Damjanović, T.,& Sladić, D.. (2002). Protolytic equlibria of bromazepam. in Journal of the Serbian Chemical Society
Srpsko hemijsko društvo, Beograd., 67(3), 187-195.
https://doi.org/10.2298/JSC0203187P

Pfendt L, Popović G, Damjanović T, Sladić D. Protolytic equlibria of bromazepam. in Journal of the Serbian Chemical Society. 2002;67(3):187-195.
doi:10.2298/JSC0203187P .

Pfendt, Lidija, Popović, Gordana, Damjanović, Tatjana, Sladić, Dušan, "Protolytic equlibria of bromazepam" in Journal of the Serbian Chemical Society, 67, no. 3 (2002):187-195,
https://doi.org/10.2298/JSC0203187P . .

TY  - CONF
AU  - Popović, Gordana
AU  - Damjanović, Tatjana
AU  - Sladić, Dušan
AU  - Pfendt, Lidija
PY  - 2002
UR  - https://farfar.pharmacy.bg.ac.rs/handle/123456789/310
PB  - Savez farmaceutskih udruženja Srbije, Beograd
C3  - Arhiv za farmaciju
T1  - Identification of the diazepine ring opening site in the reaction of acidic hydrolysis of bromazepam
T1  - Identifikacija mesta hidrolitičkog otvaranja diazepinskog prstena bromazepama u kiseloj sredini
VL  - 52
IS  - 4
SP  - 462
EP  - 463
UR  - https://hdl.handle.net/21.15107/rcub_farfar_310
ER  - 

@conference{
author = "Popović, Gordana and Damjanović, Tatjana and Sladić, Dušan and Pfendt, Lidija",
year = "2002",
publisher = "Savez farmaceutskih udruženja Srbije, Beograd",
journal = "Arhiv za farmaciju",
title = "Identification of the diazepine ring opening site in the reaction of acidic hydrolysis of bromazepam, Identifikacija mesta hidrolitičkog otvaranja diazepinskog prstena bromazepama u kiseloj sredini",
volume = "52",
number = "4",
pages = "462-463",
url = "https://hdl.handle.net/21.15107/rcub_farfar_310"
}

Popović, G., Damjanović, T., Sladić, D.,& Pfendt, L.. (2002). Identification of the diazepine ring opening site in the reaction of acidic hydrolysis of bromazepam. in Arhiv za farmaciju
Savez farmaceutskih udruženja Srbije, Beograd., 52(4), 462-463.
https://hdl.handle.net/21.15107/rcub_farfar_310

Popović G, Damjanović T, Sladić D, Pfendt L. Identification of the diazepine ring opening site in the reaction of acidic hydrolysis of bromazepam. in Arhiv za farmaciju. 2002;52(4):462-463.
https://hdl.handle.net/21.15107/rcub_farfar_310 .

Popović, Gordana, Damjanović, Tatjana, Sladić, Dušan, Pfendt, Lidija, "Identification of the diazepine ring opening site in the reaction of acidic hydrolysis of bromazepam" in Arhiv za farmaciju, 52, no. 4 (2002):462-463,
https://hdl.handle.net/21.15107/rcub_farfar_310 .

TY  - JOUR
AU  - Popović, Gordana
AU  - Pfendt, Lidija
AU  - Moskovljević, VM
PY  - 2001
UR  - https://farfar.pharmacy.bg.ac.rs/handle/123456789/300
AB  - A general derivative spectrophotometric method for determination of acidity constants is developed. The method appears suitable in cases when classical spectrophotometry cannot be employed due to little differences in the absorption spectra of conjugated acid-base pairs. Based on theoretical considerations, seven variants of the method have been established and their validity was checked, determining acidity constants of lorazepam and flurazepam as model compounds.
PB  - Elsevier Science BV, Amsterdam
T2  - Talanta
T1  - Derivative spectrophotometric method for determination of acidity constants of single step acid-base equilibria
VL  - 55
IS  - 2
SP  - 363
EP  - 370
DO  - 10.1016/S0039-9140(01)00433-7
ER  - 

@article{
author = "Popović, Gordana and Pfendt, Lidija and Moskovljević, VM",
year = "2001",
abstract = "A general derivative spectrophotometric method for determination of acidity constants is developed. The method appears suitable in cases when classical spectrophotometry cannot be employed due to little differences in the absorption spectra of conjugated acid-base pairs. Based on theoretical considerations, seven variants of the method have been established and their validity was checked, determining acidity constants of lorazepam and flurazepam as model compounds.",
publisher = "Elsevier Science BV, Amsterdam",
journal = "Talanta",
title = "Derivative spectrophotometric method for determination of acidity constants of single step acid-base equilibria",
volume = "55",
number = "2",
pages = "363-370",
doi = "10.1016/S0039-9140(01)00433-7"
}

Popović, G., Pfendt, L.,& Moskovljević, V.. (2001). Derivative spectrophotometric method for determination of acidity constants of single step acid-base equilibria. in Talanta
Elsevier Science BV, Amsterdam., 55(2), 363-370.
https://doi.org/10.1016/S0039-9140(01)00433-7

Popović G, Pfendt L, Moskovljević V. Derivative spectrophotometric method for determination of acidity constants of single step acid-base equilibria. in Talanta. 2001;55(2):363-370.
doi:10.1016/S0039-9140(01)00433-7 .

Popović, Gordana, Pfendt, Lidija, Moskovljević, VM, "Derivative spectrophotometric method for determination of acidity constants of single step acid-base equilibria" in Talanta, 55, no. 2 (2001):363-370,
https://doi.org/10.1016/S0039-9140(01)00433-7 . .

TY  - JOUR
AU  - Popović, Gordana
AU  - Pfendt, Lidija
AU  - Stefanović, Violeta M.
PY  - 2000
UR  - https://farfar.pharmacy.bg.ac.rs/handle/123456789/260
AB  - 1. Introduction 2. Basic characteristics of derivative spectrophotometry 2.1. Increase of spectra resolution 2.2. Elimination of the influence of baseline shift and matrix interferences 2.3. Enhancement of the detectability of minor spectral features 2.4. Precise determination of the positions of absorption maxima 2.5. Signal-to-noise ratio (SNR) 2.6. Quantitative analysis 3. Analytical applications 3.1. Inorganic analysis 3.2. Organic and pharmaceutical analysis 3.3. Analysis of food and water 3.4. Application of derivative spectrophotometry for the determination of equilibrium constants.
AB  - Razmatrani su osnovni principi derivativne spektrofotometrije (DS) i njene prednosti i ograničenja u odnosu na normalnu spektrofotometriju. Dat je pregled analitičke primene DS u različitim oblastima: neorganskoj i organskoj analizi, analizi farmaceutskih preparata, kliničkoj analizi, analizi hrane, hemije životne sredine, hemijskoj ravnoteži.
PB  - Srpsko hemijsko društvo, Beograd
T2  - Journal of the Serbian Chemical Society
T1  - Analytical application of derivative spectrophotometry
T1  - Analitička primena derivativne spektrofotometrije
VL  - 65
IS  - 7
SP  - 457
EP  - 472
UR  - https://hdl.handle.net/21.15107/rcub_farfar_260
ER  - 

@article{
author = "Popović, Gordana and Pfendt, Lidija and Stefanović, Violeta M.",
year = "2000",
abstract = "1. Introduction 2. Basic characteristics of derivative spectrophotometry 2.1. Increase of spectra resolution 2.2. Elimination of the influence of baseline shift and matrix interferences 2.3. Enhancement of the detectability of minor spectral features 2.4. Precise determination of the positions of absorption maxima 2.5. Signal-to-noise ratio (SNR) 2.6. Quantitative analysis 3. Analytical applications 3.1. Inorganic analysis 3.2. Organic and pharmaceutical analysis 3.3. Analysis of food and water 3.4. Application of derivative spectrophotometry for the determination of equilibrium constants., Razmatrani su osnovni principi derivativne spektrofotometrije (DS) i njene prednosti i ograničenja u odnosu na normalnu spektrofotometriju. Dat je pregled analitičke primene DS u različitim oblastima: neorganskoj i organskoj analizi, analizi farmaceutskih preparata, kliničkoj analizi, analizi hrane, hemije životne sredine, hemijskoj ravnoteži.",
publisher = "Srpsko hemijsko društvo, Beograd",
journal = "Journal of the Serbian Chemical Society",
title = "Analytical application of derivative spectrophotometry, Analitička primena derivativne spektrofotometrije",
volume = "65",
number = "7",
pages = "457-472",
url = "https://hdl.handle.net/21.15107/rcub_farfar_260"
}

Popović, G., Pfendt, L.,& Stefanović, V. M.. (2000). Analytical application of derivative spectrophotometry. in Journal of the Serbian Chemical Society
Srpsko hemijsko društvo, Beograd., 65(7), 457-472.
https://hdl.handle.net/21.15107/rcub_farfar_260

Popović G, Pfendt L, Stefanović VM. Analytical application of derivative spectrophotometry. in Journal of the Serbian Chemical Society. 2000;65(7):457-472.
https://hdl.handle.net/21.15107/rcub_farfar_260 .

Popović, Gordana, Pfendt, Lidija, Stefanović, Violeta M., "Analytical application of derivative spectrophotometry" in Journal of the Serbian Chemical Society, 65, no. 7 (2000):457-472,
https://hdl.handle.net/21.15107/rcub_farfar_260 .

TY  - JOUR
AU  - Pfendt, Lidija
AU  - Popović, Gordana
AU  - Kostić, M.
AU  - Stevović, Lj.
AU  - Drakulić, Branko
AU  - Juranić, Ivan O.
PY  - 2000
UR  - https://farfar.pharmacy.bg.ac.rs/handle/123456789/269
AB  - The pKa values for a series of eight p-substituted trans-2,3-epoxy-4-phenyl butanoic acids (p-substituted trans-β-aroylepoxyacrylic acids) have been determined potentiometrically in aqueous media at 25 °C at an ionic strength of 0.1 mol/dm3 (NaCl). The transmission of polar effects from the substituents on the phenyl nucleus to the carboxylic group through the side chain involving a carbonyl group and an epoxide ring was investigated. The pKa values were correlated with structure using the Hammett, Taft and Yukawa-Tsuno approaches. The Hammett ρ constant (0.34) was compared with analogue values for structurally similar acids.
AB  - Određene su pKa vrednosti za seriju od osam p-supstituisanih trans-2,3-epoksi-4-okso-4-fenilbutanskih kiselina (p-supstituisanih trans-β-aroilepoksiakrilnih kiselina). Vrednosti su određene potenciometrijski u vodenoj sredini na 25 °C i jonskoj sili 0.1 mol/dm3 (NaCl). Proučavan je prenos polarnih efekata sa supstituenata na fenil jezgru ka karboksilnoj grupi kroz bočni niz koji sadrži karbonilnu grupu i epoksidni prsten. pKa vrednosti su korelisane sa strukturom primenom Hammett-ovog, Taft-ovog i Yukawa-Tsuno-ovog pristupa. Hammett-ova ρ konstanta (0,34) je upoređena sa analognim vrednostima za strukturno slične kiseline.
PB  - Srpsko hemijsko društvo, Beograd
T2  - Journal of the Serbian Chemical Society
T1  - Determination and structural correlation of the pKa values of p-substituted trans-2,3-epoxy-4-oxo-4-phenylbutanoic acids
T1  - Određivanje pKa vrednosti i korelacija sa strukturom p-supstituisanih trans-2,3-epoksi-4-okso-4-fenilbutanskih kiselina
VL  - 65
IS  - 11
SP  - 781
EP  - 788
UR  - https://hdl.handle.net/21.15107/rcub_farfar_269
ER  - 

@article{
author = "Pfendt, Lidija and Popović, Gordana and Kostić, M. and Stevović, Lj. and Drakulić, Branko and Juranić, Ivan O.",
year = "2000",
abstract = "The pKa values for a series of eight p-substituted trans-2,3-epoxy-4-phenyl butanoic acids (p-substituted trans-β-aroylepoxyacrylic acids) have been determined potentiometrically in aqueous media at 25 °C at an ionic strength of 0.1 mol/dm3 (NaCl). The transmission of polar effects from the substituents on the phenyl nucleus to the carboxylic group through the side chain involving a carbonyl group and an epoxide ring was investigated. The pKa values were correlated with structure using the Hammett, Taft and Yukawa-Tsuno approaches. The Hammett ρ constant (0.34) was compared with analogue values for structurally similar acids., Određene su pKa vrednosti za seriju od osam p-supstituisanih trans-2,3-epoksi-4-okso-4-fenilbutanskih kiselina (p-supstituisanih trans-β-aroilepoksiakrilnih kiselina). Vrednosti su određene potenciometrijski u vodenoj sredini na 25 °C i jonskoj sili 0.1 mol/dm3 (NaCl). Proučavan je prenos polarnih efekata sa supstituenata na fenil jezgru ka karboksilnoj grupi kroz bočni niz koji sadrži karbonilnu grupu i epoksidni prsten. pKa vrednosti su korelisane sa strukturom primenom Hammett-ovog, Taft-ovog i Yukawa-Tsuno-ovog pristupa. Hammett-ova ρ konstanta (0,34) je upoređena sa analognim vrednostima za strukturno slične kiseline.",
publisher = "Srpsko hemijsko društvo, Beograd",
journal = "Journal of the Serbian Chemical Society",
title = "Determination and structural correlation of the pKa values of p-substituted trans-2,3-epoxy-4-oxo-4-phenylbutanoic acids, Određivanje pKa vrednosti i korelacija sa strukturom p-supstituisanih trans-2,3-epoksi-4-okso-4-fenilbutanskih kiselina",
volume = "65",
number = "11",
pages = "781-788",
url = "https://hdl.handle.net/21.15107/rcub_farfar_269"
}

Pfendt, L., Popović, G., Kostić, M., Stevović, Lj., Drakulić, B.,& Juranić, I. O.. (2000). Determination and structural correlation of the pKa values of p-substituted trans-2,3-epoxy-4-oxo-4-phenylbutanoic acids. in Journal of the Serbian Chemical Society
Srpsko hemijsko društvo, Beograd., 65(11), 781-788.
https://hdl.handle.net/21.15107/rcub_farfar_269

Pfendt L, Popović G, Kostić M, Stevović L, Drakulić B, Juranić IO. Determination and structural correlation of the pKa values of p-substituted trans-2,3-epoxy-4-oxo-4-phenylbutanoic acids. in Journal of the Serbian Chemical Society. 2000;65(11):781-788.
https://hdl.handle.net/21.15107/rcub_farfar_269 .

Pfendt, Lidija, Popović, Gordana, Kostić, M., Stevović, Lj., Drakulić, Branko, Juranić, Ivan O., "Determination and structural correlation of the pKa values of p-substituted trans-2,3-epoxy-4-oxo-4-phenylbutanoic acids" in Journal of the Serbian Chemical Society, 65, no. 11 (2000):781-788,
https://hdl.handle.net/21.15107/rcub_farfar_269 .

TY  - JOUR
AU  - Popović, Gordana
AU  - Dražić, Branka
AU  - Pfendt, Lidija
PY  - 1998
UR  - https://farfar.pharmacy.bg.ac.rs/handle/123456789/196
PB  - Govi-Verlag Gmbh, Eschborn
T2  - Pharmazie
T1  - Acid-base equilibria in homogeneous and heterogeneous systems of clonazepam and nitrazepam
VL  - 53
IS  - 9
SP  - 647
EP  - 649
UR  - https://hdl.handle.net/21.15107/rcub_farfar_196
ER  - 

@article{
author = "Popović, Gordana and Dražić, Branka and Pfendt, Lidija",
year = "1998",
publisher = "Govi-Verlag Gmbh, Eschborn",
journal = "Pharmazie",
title = "Acid-base equilibria in homogeneous and heterogeneous systems of clonazepam and nitrazepam",
volume = "53",
number = "9",
pages = "647-649",
url = "https://hdl.handle.net/21.15107/rcub_farfar_196"
}

Popović, G., Dražić, B.,& Pfendt, L.. (1998). Acid-base equilibria in homogeneous and heterogeneous systems of clonazepam and nitrazepam. in Pharmazie
Govi-Verlag Gmbh, Eschborn., 53(9), 647-649.
https://hdl.handle.net/21.15107/rcub_farfar_196

Popović G, Dražić B, Pfendt L. Acid-base equilibria in homogeneous and heterogeneous systems of clonazepam and nitrazepam. in Pharmazie. 1998;53(9):647-649.
https://hdl.handle.net/21.15107/rcub_farfar_196 .

Popović, Gordana, Dražić, Branka, Pfendt, Lidija, "Acid-base equilibria in homogeneous and heterogeneous systems of clonazepam and nitrazepam" in Pharmazie, 53, no. 9 (1998):647-649,
https://hdl.handle.net/21.15107/rcub_farfar_196 .

TY  - JOUR
AU  - Pfendt, Lidija
AU  - Popović, Gordana
AU  - Stefanović, Violeta M.
AU  - Rajić, M.B
PY  - 1997
UR  - https://farfar.pharmacy.bg.ac.rs/handle/123456789/171
AB  - A second-order derivative ultraviolet spectroscopic method for the determination of midazolam in the presence of maleic acid is described. The assays were carried out in borate buffer (pH 9.2) at a wavelength of 222 nm, which corresponds to the position of the peak of 2 D spectrum of midazolam and to the intersection point of the 2 D spectrum of maleic acid with the abscissa (zero-crossing point). These conditions were chosen as optimum on the basis of the knowledge of acid-base equilibria of midazolam and maleic acid and of investigations of the absorption and 2 D spectra of midazolam and maleic acid and their mixtures. A calibration graph was obtained in the range of midazolam concentrations of 0.25-2.5x10 -5 mol/dm 3 with a correlation coefficient of 0.99996. The method is simple and rapid, and was successfully applied to the determination of midazolam in the presence of maleic acid in laboratory mixtures and in commercial tablets containing midazolam in the maleate form.
PB  - Srpsko hemijsko društvo, Beograd
T2  - Journal of the Serbian Chemical Society
T1  - Determination of midazolam in pharmaceutical dosage forms by second-order derivative ultraviolet spectrophotometry
VL  - 62
IS  - 8
SP  - 687
EP  - 693
UR  - https://hdl.handle.net/21.15107/rcub_farfar_171
ER  - 

@article{
author = "Pfendt, Lidija and Popović, Gordana and Stefanović, Violeta M. and Rajić, M.B",
year = "1997",
abstract = "A second-order derivative ultraviolet spectroscopic method for the determination of midazolam in the presence of maleic acid is described. The assays were carried out in borate buffer (pH 9.2) at a wavelength of 222 nm, which corresponds to the position of the peak of 2 D spectrum of midazolam and to the intersection point of the 2 D spectrum of maleic acid with the abscissa (zero-crossing point). These conditions were chosen as optimum on the basis of the knowledge of acid-base equilibria of midazolam and maleic acid and of investigations of the absorption and 2 D spectra of midazolam and maleic acid and their mixtures. A calibration graph was obtained in the range of midazolam concentrations of 0.25-2.5x10 -5 mol/dm 3 with a correlation coefficient of 0.99996. The method is simple and rapid, and was successfully applied to the determination of midazolam in the presence of maleic acid in laboratory mixtures and in commercial tablets containing midazolam in the maleate form.",
publisher = "Srpsko hemijsko društvo, Beograd",
journal = "Journal of the Serbian Chemical Society",
title = "Determination of midazolam in pharmaceutical dosage forms by second-order derivative ultraviolet spectrophotometry",
volume = "62",
number = "8",
pages = "687-693",
url = "https://hdl.handle.net/21.15107/rcub_farfar_171"
}

Pfendt, L., Popović, G., Stefanović, V. M.,& Rajić, M.B. (1997). Determination of midazolam in pharmaceutical dosage forms by second-order derivative ultraviolet spectrophotometry. in Journal of the Serbian Chemical Society
Srpsko hemijsko društvo, Beograd., 62(8), 687-693.
https://hdl.handle.net/21.15107/rcub_farfar_171

Pfendt L, Popović G, Stefanović VM, Rajić M. Determination of midazolam in pharmaceutical dosage forms by second-order derivative ultraviolet spectrophotometry. in Journal of the Serbian Chemical Society. 1997;62(8):687-693.
https://hdl.handle.net/21.15107/rcub_farfar_171 .

Pfendt, Lidija, Popović, Gordana, Stefanović, Violeta M., Rajić, M.B, "Determination of midazolam in pharmaceutical dosage forms by second-order derivative ultraviolet spectrophotometry" in Journal of the Serbian Chemical Society, 62, no. 8 (1997):687-693,
https://hdl.handle.net/21.15107/rcub_farfar_171 .

TY  - JOUR
AU  - Popović, Gordana
AU  - Pfendt, Lidija
PY  - 1996
UR  - https://farfar.pharmacy.bg.ac.rs/handle/123456789/144
AB  - Two spectrophotometric methods are proposed for the determination of flurazepam in pharmaceutical formulations. The first one, a very sensitive and fast direct spectrophotometric method is based on the measurement of the absorbance of aqueous flurazepam monohydrochloride solution (pH 6) at the wavelength of maximum absorption at 230 nm. The second one, a difference spectrophotometric method, is based on the measurement of the absorbance difference between equimolar solutions of flurazepam monoprotonated (pH 6) and diprotonated (pH 0) forms at 225 nm. Both methods were applied to the determination of flurazepam in capsules which contain flurazepam monohydrochloride. To extend the application range of both methods, we examined optimum conditions which enable the determination of flurazepam in formulations in form of flurazepam dihydrochloride.
PB  - Editions Scientifiques Elsevier, Paris Cedex 15
T2  - Analusis
T1  - Spectrophotometric determination of flurazepam in pharmaceutical formulations
VL  - 24
IS  - 6
SP  - 259
EP  - 262
UR  - https://hdl.handle.net/21.15107/rcub_farfar_144
ER  - 

@article{
author = "Popović, Gordana and Pfendt, Lidija",
year = "1996",
abstract = "Two spectrophotometric methods are proposed for the determination of flurazepam in pharmaceutical formulations. The first one, a very sensitive and fast direct spectrophotometric method is based on the measurement of the absorbance of aqueous flurazepam monohydrochloride solution (pH 6) at the wavelength of maximum absorption at 230 nm. The second one, a difference spectrophotometric method, is based on the measurement of the absorbance difference between equimolar solutions of flurazepam monoprotonated (pH 6) and diprotonated (pH 0) forms at 225 nm. Both methods were applied to the determination of flurazepam in capsules which contain flurazepam monohydrochloride. To extend the application range of both methods, we examined optimum conditions which enable the determination of flurazepam in formulations in form of flurazepam dihydrochloride.",
publisher = "Editions Scientifiques Elsevier, Paris Cedex 15",
journal = "Analusis",
title = "Spectrophotometric determination of flurazepam in pharmaceutical formulations",
volume = "24",
number = "6",
pages = "259-262",
url = "https://hdl.handle.net/21.15107/rcub_farfar_144"
}

Popović, G.,& Pfendt, L.. (1996). Spectrophotometric determination of flurazepam in pharmaceutical formulations. in Analusis
Editions Scientifiques Elsevier, Paris Cedex 15., 24(6), 259-262.
https://hdl.handle.net/21.15107/rcub_farfar_144

Popović G, Pfendt L. Spectrophotometric determination of flurazepam in pharmaceutical formulations. in Analusis. 1996;24(6):259-262.
https://hdl.handle.net/21.15107/rcub_farfar_144 .

Popović, Gordana, Pfendt, Lidija, "Spectrophotometric determination of flurazepam in pharmaceutical formulations" in Analusis, 24, no. 6 (1996):259-262,
https://hdl.handle.net/21.15107/rcub_farfar_144 .

TY  - JOUR
AU  - Pfendt, Lidija
AU  - Popović, Gordana
AU  - Supančić, S.I
PY  - 1995
UR  - https://farfar.pharmacy.bg.ac.rs/handle/123456789/128
T2  - Journal of Pharmaceutical and Biomedical Analysis
T1  - Spectrophotometric determination of midazolam in pharmaceutical formulations
VL  - 13
IS  - 12
SP  - 1551
EP  - 1553
DO  - 10.1016/0731-7085(95)01570-1
ER  - 

@article{
author = "Pfendt, Lidija and Popović, Gordana and Supančić, S.I",
year = "1995",
journal = "Journal of Pharmaceutical and Biomedical Analysis",
title = "Spectrophotometric determination of midazolam in pharmaceutical formulations",
volume = "13",
number = "12",
pages = "1551-1553",
doi = "10.1016/0731-7085(95)01570-1"
}

Pfendt, L., Popović, G.,& Supančić, S.I. (1995). Spectrophotometric determination of midazolam in pharmaceutical formulations. in Journal of Pharmaceutical and Biomedical Analysis, 13(12), 1551-1553.
https://doi.org/10.1016/0731-7085(95)01570-1

Pfendt L, Popović G, Supančić S. Spectrophotometric determination of midazolam in pharmaceutical formulations. in Journal of Pharmaceutical and Biomedical Analysis. 1995;13(12):1551-1553.
doi:10.1016/0731-7085(95)01570-1 .

Pfendt, Lidija, Popović, Gordana, Supančić, S.I, "Spectrophotometric determination of midazolam in pharmaceutical formulations" in Journal of Pharmaceutical and Biomedical Analysis, 13, no. 12 (1995):1551-1553,
https://doi.org/10.1016/0731-7085(95)01570-1 . .

TY  - JOUR
AU  - Pfendt, Lidija
AU  - Janjić, T.J
AU  - Popović, Gordana
PY  - 1995
UR  - https://farfar.pharmacy.bg.ac.rs/handle/123456789/123
AB  - Protolytic equilibria of midazolam in the pH range 0-12 were investigated. Acidity, hydrolysis, equilibrium constants in the heterogeneous system and the solubility of midazolam were determined [I = 0.1 mol l-1 (NaCl), 25 °C]. A spectrophotometric method was developed for the investigation of the mechanism of hydrolysis and the determination of the corresponding equilibrium constants. In addition, buffer characteristics of the two-phase and single-phase midazolam buffers were investigated.
T2  - The Analyst
T1  - Study of protolytic, hydrolytic and solubility equilibria of midazolam
VL  - 120
IS  - 8
SP  - 2145
EP  - 2151
DO  - 10.1039/AN9952002145
ER  - 

@article{
author = "Pfendt, Lidija and Janjić, T.J and Popović, Gordana",
year = "1995",
abstract = "Protolytic equilibria of midazolam in the pH range 0-12 were investigated. Acidity, hydrolysis, equilibrium constants in the heterogeneous system and the solubility of midazolam were determined [I = 0.1 mol l-1 (NaCl), 25 °C]. A spectrophotometric method was developed for the investigation of the mechanism of hydrolysis and the determination of the corresponding equilibrium constants. In addition, buffer characteristics of the two-phase and single-phase midazolam buffers were investigated.",
journal = "The Analyst",
title = "Study of protolytic, hydrolytic and solubility equilibria of midazolam",
volume = "120",
number = "8",
pages = "2145-2151",
doi = "10.1039/AN9952002145"
}

Pfendt, L., Janjić, T.J,& Popović, G.. (1995). Study of protolytic, hydrolytic and solubility equilibria of midazolam. in The Analyst, 120(8), 2145-2151.
https://doi.org/10.1039/AN9952002145

Pfendt L, Janjić T, Popović G. Study of protolytic, hydrolytic and solubility equilibria of midazolam. in The Analyst. 1995;120(8):2145-2151.
doi:10.1039/AN9952002145 .

Pfendt, Lidija, Janjić, T.J, Popović, Gordana, "Study of protolytic, hydrolytic and solubility equilibria of midazolam" in The Analyst, 120, no. 8 (1995):2145-2151,
https://doi.org/10.1039/AN9952002145 . .

TY  - JOUR
AU  - Pfendt, Lidija
AU  - Popović, Gordana
PY  - 1994
UR  - https://farfar.pharmacy.bg.ac.rs/handle/123456789/108
AB  - A general spectrophotometric method is proposed for the quantitative investigation of the hydrolysis of 1,4-benzodiazepines which, under the effect of nucleophilic hydration, undergo reversible cleavage of the 4,5-azomethine bond, followed by simultaneous simple acid-base reactions. The method is based on establishing the pH region of the solution in which, at the state of complete equilibration, three species dominate, as well as on using suitable isosbestic points and the differences in rates of simple protolysis and hydrolysis. The method is presented using flurazepam as an example, but it also can be applied to other compounds which hydrolyse by a similar mechanism.
T2  - Journal of the Chemical Society, Perkin Transactions 2
T1  - A spectrophotometric method for the determination of equilibrium constants of the reversible 1,4-benzodiazepine ring-opening reaction
IS  - 8
SP  - 1845
EP  - 1848
UR  - https://hdl.handle.net/21.15107/rcub_farfar_108
ER  - 

@article{
author = "Pfendt, Lidija and Popović, Gordana",
year = "1994",
abstract = "A general spectrophotometric method is proposed for the quantitative investigation of the hydrolysis of 1,4-benzodiazepines which, under the effect of nucleophilic hydration, undergo reversible cleavage of the 4,5-azomethine bond, followed by simultaneous simple acid-base reactions. The method is based on establishing the pH region of the solution in which, at the state of complete equilibration, three species dominate, as well as on using suitable isosbestic points and the differences in rates of simple protolysis and hydrolysis. The method is presented using flurazepam as an example, but it also can be applied to other compounds which hydrolyse by a similar mechanism.",
journal = "Journal of the Chemical Society, Perkin Transactions 2",
title = "A spectrophotometric method for the determination of equilibrium constants of the reversible 1,4-benzodiazepine ring-opening reaction",
number = "8",
pages = "1845-1848",
url = "https://hdl.handle.net/21.15107/rcub_farfar_108"
}

Pfendt, L.,& Popović, G.. (1994). A spectrophotometric method for the determination of equilibrium constants of the reversible 1,4-benzodiazepine ring-opening reaction. in Journal of the Chemical Society, Perkin Transactions 2(8), 1845-1848.
https://hdl.handle.net/21.15107/rcub_farfar_108

Pfendt L, Popović G. A spectrophotometric method for the determination of equilibrium constants of the reversible 1,4-benzodiazepine ring-opening reaction. in Journal of the Chemical Society, Perkin Transactions 2. 1994;(8):1845-1848.
https://hdl.handle.net/21.15107/rcub_farfar_108 .

Pfendt, Lidija, Popović, Gordana, "A spectrophotometric method for the determination of equilibrium constants of the reversible 1,4-benzodiazepine ring-opening reaction" in Journal of the Chemical Society, Perkin Transactions 2, no. 8 (1994):1845-1848,
https://hdl.handle.net/21.15107/rcub_farfar_108 .

TY  - JOUR
AU  - Pfendt, Lidija
AU  - Sladić, Dušan
AU  - Janjić, T.J
AU  - Popović, Gordana
PY  - 1990
UR  - https://farfar.pharmacy.bg.ac.rs/handle/123456789/76
AB  - Acid-base equilibria in heterogeneous and homogeneous systems of some sparingly soluble benzodiazepines (diazepam, prazepam, chlordiazepoxide and medazepam) were investigated in aqueous solution and the corresponding equilibrium constants were determined by the application of pH-metric, spectrophotometric and solubility methods. The sites of protonation were predicted on the basis of the analysis of the corresponding carbon-13 nuclear magnetic resonance spectra. In addition, buffer characteristics of saturated aqueous solutions of these drugs in the presence of the solid phase were investigated and it was established that they possess a very high buffer capacity over a specific pH range.
T2  - The Analyst
T1  - Study of heterogeneous equilibria in saturated aqueous solutions of some 7-chloro-1,4-benzodiazepines
VL  - 115
IS  - 4
SP  - 383
EP  - 387
DO  - 10.1039/an9901500383
ER  - 

@article{
author = "Pfendt, Lidija and Sladić, Dušan and Janjić, T.J and Popović, Gordana",
year = "1990",
abstract = "Acid-base equilibria in heterogeneous and homogeneous systems of some sparingly soluble benzodiazepines (diazepam, prazepam, chlordiazepoxide and medazepam) were investigated in aqueous solution and the corresponding equilibrium constants were determined by the application of pH-metric, spectrophotometric and solubility methods. The sites of protonation were predicted on the basis of the analysis of the corresponding carbon-13 nuclear magnetic resonance spectra. In addition, buffer characteristics of saturated aqueous solutions of these drugs in the presence of the solid phase were investigated and it was established that they possess a very high buffer capacity over a specific pH range.",
journal = "The Analyst",
title = "Study of heterogeneous equilibria in saturated aqueous solutions of some 7-chloro-1,4-benzodiazepines",
volume = "115",
number = "4",
pages = "383-387",
doi = "10.1039/an9901500383"
}

Pfendt, L., Sladić, D., Janjić, T.J,& Popović, G.. (1990). Study of heterogeneous equilibria in saturated aqueous solutions of some 7-chloro-1,4-benzodiazepines. in The Analyst, 115(4), 383-387.
https://doi.org/10.1039/an9901500383

Pfendt L, Sladić D, Janjić T, Popović G. Study of heterogeneous equilibria in saturated aqueous solutions of some 7-chloro-1,4-benzodiazepines. in The Analyst. 1990;115(4):383-387.
doi:10.1039/an9901500383 .

Pfendt, Lidija, Sladić, Dušan, Janjić, T.J, Popović, Gordana, "Study of heterogeneous equilibria in saturated aqueous solutions of some 7-chloro-1,4-benzodiazepines" in The Analyst, 115, no. 4 (1990):383-387,
https://doi.org/10.1039/an9901500383 . .

TY  - JOUR
AU  - Pfendt, Lidija
AU  - Janjić, T.J
AU  - Popović, Gordana
PY  - 1990
UR  - https://farfar.pharmacy.bg.ac.rs/handle/123456789/75
AB  - Protolytic equilibria of flurazepam, a diprotic base which is sparingly soluble in water, were investigated. The investigations were carried out in the pH range 0-12, at constant ionic strength (0.1 M NaCl) and 25 ± 0.1 °C, by the application of spectrophotometric, pH-metric and solubility methods. The acidity, hydrolysis and equilibrium constants in the heterogeneous system were determined. In addition, a method, based on the application of a formation function to the hydrolytic process, is proposed. Finally, buffer characteristics of flurazepam in the homogeneous and heterogeneous systems were studied.
T2  - The Analyst
T1  - Study of protolytic equilibria of flurazepam
VL  - 115
IS  - 11
SP  - 1457
EP  - 1462
DO  - 10.1039/an9901501457
ER  - 

@article{
author = "Pfendt, Lidija and Janjić, T.J and Popović, Gordana",
year = "1990",
abstract = "Protolytic equilibria of flurazepam, a diprotic base which is sparingly soluble in water, were investigated. The investigations were carried out in the pH range 0-12, at constant ionic strength (0.1 M NaCl) and 25 ± 0.1 °C, by the application of spectrophotometric, pH-metric and solubility methods. The acidity, hydrolysis and equilibrium constants in the heterogeneous system were determined. In addition, a method, based on the application of a formation function to the hydrolytic process, is proposed. Finally, buffer characteristics of flurazepam in the homogeneous and heterogeneous systems were studied.",
journal = "The Analyst",
title = "Study of protolytic equilibria of flurazepam",
volume = "115",
number = "11",
pages = "1457-1462",
doi = "10.1039/an9901501457"
}

Pfendt, L., Janjić, T.J,& Popović, G.. (1990). Study of protolytic equilibria of flurazepam. in The Analyst, 115(11), 1457-1462.
https://doi.org/10.1039/an9901501457

Pfendt L, Janjić T, Popović G. Study of protolytic equilibria of flurazepam. in The Analyst. 1990;115(11):1457-1462.
doi:10.1039/an9901501457 .

Pfendt, Lidija, Janjić, T.J, Popović, Gordana, "Study of protolytic equilibria of flurazepam" in The Analyst, 115, no. 11 (1990):1457-1462,
https://doi.org/10.1039/an9901501457 . .