TY  - JOUR
AU  - Janosevic-Lezaic, Aleksandra
AU  - Pejic, Nataša
AU  - Goronja, Jelena
AU  - Pavun, Leposava
AU  - Đikanović, Daniela
AU  - Malenović, Andelija
PY  - 2021
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1480
AB  - The effect of acetonitrile (ACN) on the micellization of a cationic surfactant, cetyltrimethylammo-nium bromide (CTAB), in aqueous solutions at different temperatures was studied. The critical micellar concentration (CMC) as well as the degree of counter ion dissociation (a) of CTAB in aqueous ACN mixtures (10-20 % v/v) at various temperatures (291.2-298.2 K) were determined by electrical conduc-tivity measurements, while steady-state fluorescence measurements were used to determine several CMCs (for comparison) and a micellar aggregation number (N-agg) as well. At a fixed temperature, both an increase in CMC and a decrease in N-agg were observed for an increase in ACN in the solvent mixture. With a temperature increase, CMC values increased for 10 % (v/v) ACN, while for both 15 % and 20 % (v/v) ACN, CMC values were a minimum at T = 295.2 K with a temperature increase. In addition, some aspects related to the Krafft temperature behavior of CTAB in the examined micellar systems are discussed.
PB  - Soc Chemists Technologists Madeconia, Skopje
T2  - Macedonian Journal of Chemistry and Chemical Engineering
T1  - Micellar properties of cetyltrimethylammonium bromide in an acetonitrile-water mixture: conductometric and fluorescence studies
EP  - 287
IS  - 2
SP  - 277
VL  - 40
DO  - 10.20450/mjcce.2021.2394
ER  - 

@article{
author = "Janosevic-Lezaic, Aleksandra and Pejic, Nataša and Goronja, Jelena and Pavun, Leposava and Đikanović, Daniela and Malenović, Andelija",
year = "2021",
abstract = "The effect of acetonitrile (ACN) on the micellization of a cationic surfactant, cetyltrimethylammo-nium bromide (CTAB), in aqueous solutions at different temperatures was studied. The critical micellar concentration (CMC) as well as the degree of counter ion dissociation (a) of CTAB in aqueous ACN mixtures (10-20 % v/v) at various temperatures (291.2-298.2 K) were determined by electrical conduc-tivity measurements, while steady-state fluorescence measurements were used to determine several CMCs (for comparison) and a micellar aggregation number (N-agg) as well. At a fixed temperature, both an increase in CMC and a decrease in N-agg were observed for an increase in ACN in the solvent mixture. With a temperature increase, CMC values increased for 10 % (v/v) ACN, while for both 15 % and 20 % (v/v) ACN, CMC values were a minimum at T = 295.2 K with a temperature increase. In addition, some aspects related to the Krafft temperature behavior of CTAB in the examined micellar systems are discussed.",
publisher = "Soc Chemists Technologists Madeconia, Skopje",
journal = "Macedonian Journal of Chemistry and Chemical Engineering",
title = "Micellar properties of cetyltrimethylammonium bromide in an acetonitrile-water mixture: conductometric and fluorescence studies",
pages = "287-277",
number = "2",
volume = "40",
doi = "10.20450/mjcce.2021.2394"
}

Janosevic-Lezaic, A., Pejic, N., Goronja, J., Pavun, L., Đikanović, D.,& Malenović, A.. (2021). Micellar properties of cetyltrimethylammonium bromide in an acetonitrile-water mixture: conductometric and fluorescence studies. in Macedonian Journal of Chemistry and Chemical Engineering
Soc Chemists Technologists Madeconia, Skopje., 40(2), 277-287.
https://doi.org/10.20450/mjcce.2021.2394

Janosevic-Lezaic A, Pejic N, Goronja J, Pavun L, Đikanović D, Malenović A. Micellar properties of cetyltrimethylammonium bromide in an acetonitrile-water mixture: conductometric and fluorescence studies. in Macedonian Journal of Chemistry and Chemical Engineering. 2021;40(2):277-287.
doi:10.20450/mjcce.2021.2394 .

Janosevic-Lezaic, Aleksandra, Pejic, Nataša, Goronja, Jelena, Pavun, Leposava, Đikanović, Daniela, Malenović, Andelija, "Micellar properties of cetyltrimethylammonium bromide in an acetonitrile-water mixture: conductometric and fluorescence studies" in Macedonian Journal of Chemistry and Chemical Engineering, 40, no. 2 (2021):277-287,
https://doi.org/10.20450/mjcce.2021.2394 . .

TY  - JOUR
AU  - Pavun, Leposava
AU  - Uskokovic-Marković, Snežana
AU  - Jelikic-Stankov, Milena
AU  - Đikanović, Daniela
AU  - Durdević, Predrag
PY  - 2018
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1135
AB  - We propose a sensitive and selective spectrofluorimetric method for the determination of flavonoids as expressed in 'quercetin equivalent' in apple juices. The method is based on the strong emission of the aluminium(III)-quercetin complex at 480 nm with excitation at 420 nm, and it is successfully applied for the determination of flavonoids in commercial apple juices and compared with results obtained in reference spectrophotometric determination. The flavonoid content in commercial apple juices was found to range from 5.53 to 15.55 mg/l quercetin equivalent. The very good agreement between the two methods indicates the suitability of the proposed spectrofluorimetric method for the precise and accurate determination of flavonoids. In addition, the total polyphenol content was determined spectrophotometrically using the Folin-Ciocalteu (FC) method and the antioxidative activity of the tested juices was tested in a DPPH assay and these values were correlated with each other. The obtained profiles of compounds with antioxidative ability lead us to conclude that fruit juice labels based only on fruit % might sometimes misinform consumers.
PB  - Czech Academy Agricultural Sciences, Prague
T2  - Czech Journal of Food Sciences
T1  - Determination of Flavonoids and Total Polyphenol Contents in Commercial Apple Juices
EP  - 238
IS  - 3
SP  - 233
VL  - 36
DO  - 10.17221/211/2017-CJFS
ER  - 

@article{
author = "Pavun, Leposava and Uskokovic-Marković, Snežana and Jelikic-Stankov, Milena and Đikanović, Daniela and Durdević, Predrag",
year = "2018",
abstract = "We propose a sensitive and selective spectrofluorimetric method for the determination of flavonoids as expressed in 'quercetin equivalent' in apple juices. The method is based on the strong emission of the aluminium(III)-quercetin complex at 480 nm with excitation at 420 nm, and it is successfully applied for the determination of flavonoids in commercial apple juices and compared with results obtained in reference spectrophotometric determination. The flavonoid content in commercial apple juices was found to range from 5.53 to 15.55 mg/l quercetin equivalent. The very good agreement between the two methods indicates the suitability of the proposed spectrofluorimetric method for the precise and accurate determination of flavonoids. In addition, the total polyphenol content was determined spectrophotometrically using the Folin-Ciocalteu (FC) method and the antioxidative activity of the tested juices was tested in a DPPH assay and these values were correlated with each other. The obtained profiles of compounds with antioxidative ability lead us to conclude that fruit juice labels based only on fruit % might sometimes misinform consumers.",
publisher = "Czech Academy Agricultural Sciences, Prague",
journal = "Czech Journal of Food Sciences",
title = "Determination of Flavonoids and Total Polyphenol Contents in Commercial Apple Juices",
pages = "238-233",
number = "3",
volume = "36",
doi = "10.17221/211/2017-CJFS"
}

Pavun, L., Uskokovic-Marković, S., Jelikic-Stankov, M., Đikanović, D.,& Durdević, P.. (2018). Determination of Flavonoids and Total Polyphenol Contents in Commercial Apple Juices. in Czech Journal of Food Sciences
Czech Academy Agricultural Sciences, Prague., 36(3), 233-238.
https://doi.org/10.17221/211/2017-CJFS

Pavun L, Uskokovic-Marković S, Jelikic-Stankov M, Đikanović D, Durdević P. Determination of Flavonoids and Total Polyphenol Contents in Commercial Apple Juices. in Czech Journal of Food Sciences. 2018;36(3):233-238.
doi:10.17221/211/2017-CJFS .

Pavun, Leposava, Uskokovic-Marković, Snežana, Jelikic-Stankov, Milena, Đikanović, Daniela, Durdević, Predrag, "Determination of Flavonoids and Total Polyphenol Contents in Commercial Apple Juices" in Czech Journal of Food Sciences, 36, no. 3 (2018):233-238,
https://doi.org/10.17221/211/2017-CJFS . .

TY  - JOUR
AU  - Pavun, Leposava
AU  - Durdević, Predrag
AU  - Jelikic-Stankov, Milena
AU  - Đikanović, Daniela
AU  - Ciric, Andrija
AU  - Uskokovic-Marković, Snežana
PY  - 2014
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/799
AB  - A simple, accurate and precise method based on the fluorescence properties of the aluminum(III)-quercetin complex, for the determination of quercetin, has been developed and validated. The complex has strong emission at pH 3.30, lambda(em) = 480 nm, with lambda(ex) = 420 nm. The linearity range of quercetin determination was 1.5-60.5 ng ml(-1) with LOD 0.09 ng ml(-1) and LOQ 0.27 ng ml(-1). Recovery values in the range of 99.9-100.2% indicate a good accuracy of the method. The established method was applied for the determination of quercetin in capsules, with a recovery value of 98.3%, standard deviation of 0.22% and coefficient of variation of 0.09%. The reliability of the method was checked by the newly developed RP-HPLC/UV method for capsules with the direct determination of quercetin after separation. The good agreement between the two methods indicates the applicability of the proposed spectrofluorimetric method for quercetin determination in pharmaceutical dosage forms, with high reproducibility, and enables the direct and simple determination without its prior extraction from samples. The proposed spectrofluorimetric method has much better sensitivity and LOD and LOQ values that are about 1000 times lower than data reported in the literature.
PB  - Soc Chemists Technologists Madeconia, Skopje
T2  - Macedonian Journal of Chemistry and Chemical Engineering
T1  - Spectrofluorimetric determination of quercetin in pharmaceutical dosage forms
EP  - 215
IS  - 2
SP  - 209
VL  - 33
DO  - 10.20450/mjcce.2014.496
ER  - 

@article{
author = "Pavun, Leposava and Durdević, Predrag and Jelikic-Stankov, Milena and Đikanović, Daniela and Ciric, Andrija and Uskokovic-Marković, Snežana",
year = "2014",
abstract = "A simple, accurate and precise method based on the fluorescence properties of the aluminum(III)-quercetin complex, for the determination of quercetin, has been developed and validated. The complex has strong emission at pH 3.30, lambda(em) = 480 nm, with lambda(ex) = 420 nm. The linearity range of quercetin determination was 1.5-60.5 ng ml(-1) with LOD 0.09 ng ml(-1) and LOQ 0.27 ng ml(-1). Recovery values in the range of 99.9-100.2% indicate a good accuracy of the method. The established method was applied for the determination of quercetin in capsules, with a recovery value of 98.3%, standard deviation of 0.22% and coefficient of variation of 0.09%. The reliability of the method was checked by the newly developed RP-HPLC/UV method for capsules with the direct determination of quercetin after separation. The good agreement between the two methods indicates the applicability of the proposed spectrofluorimetric method for quercetin determination in pharmaceutical dosage forms, with high reproducibility, and enables the direct and simple determination without its prior extraction from samples. The proposed spectrofluorimetric method has much better sensitivity and LOD and LOQ values that are about 1000 times lower than data reported in the literature.",
publisher = "Soc Chemists Technologists Madeconia, Skopje",
journal = "Macedonian Journal of Chemistry and Chemical Engineering",
title = "Spectrofluorimetric determination of quercetin in pharmaceutical dosage forms",
pages = "215-209",
number = "2",
volume = "33",
doi = "10.20450/mjcce.2014.496"
}

Pavun, L., Durdević, P., Jelikic-Stankov, M., Đikanović, D., Ciric, A.,& Uskokovic-Marković, S.. (2014). Spectrofluorimetric determination of quercetin in pharmaceutical dosage forms. in Macedonian Journal of Chemistry and Chemical Engineering
Soc Chemists Technologists Madeconia, Skopje., 33(2), 209-215.
https://doi.org/10.20450/mjcce.2014.496

Pavun L, Durdević P, Jelikic-Stankov M, Đikanović D, Ciric A, Uskokovic-Marković S. Spectrofluorimetric determination of quercetin in pharmaceutical dosage forms. in Macedonian Journal of Chemistry and Chemical Engineering. 2014;33(2):209-215.
doi:10.20450/mjcce.2014.496 .

Pavun, Leposava, Durdević, Predrag, Jelikic-Stankov, Milena, Đikanović, Daniela, Ciric, Andrija, Uskokovic-Marković, Snežana, "Spectrofluorimetric determination of quercetin in pharmaceutical dosage forms" in Macedonian Journal of Chemistry and Chemical Engineering, 33, no. 2 (2014):209-215,
https://doi.org/10.20450/mjcce.2014.496 . .

TY  - JOUR
AU  - Pavun, Leposava A
AU  - Dimitrić-Marković, Jasmina
AU  - Djurdjević, Predrag T
AU  - Jelikic-Stankov, Milena D
AU  - Đikanović, Daniela
AU  - Ciric, Andrija
AU  - Malesev, Dusan L
PY  - 2012
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/512
AB  - A fluorometric method, based on the fluorescence properties of the aluminium(III)-hesperidin complex, for the determination of hesperidin in human plasma and pharmaceutical forms has been developed and validated. The complex shows a strong emission in the presence of the surfactant betain sulphonate SB 12 at 476 nm with excitation at 390 nm. The linearity range for pharmaceutical forms of hesperidin was 0.06-24.4 mu g mL(-1) with a limit of detection, LOD, of 0.016 mu g mL(-1) and a limit of quantification, LOQ, of 0.049 mu g mL(-1). Recovery values in the range 99.3-99.7 % indicate good accuracy of the method. A linear dependence of the intensity of fluorescence of the complex on the concentration of hesperidin in plasma was obtained in concentration range from 0.1-12.2 mu g mL(-1). The LOD was 0.032 mu g mL(-1) while LOQ was 0.096 mu g mL(-1). Recovery values were in the range 98.4-99.8 %. The reliability of the method was checked by an LC MS/MS method for plasma samples and an HPLC/UV method for tablets with direct determination of hesperidin after separation. Linearity range in determination of hesperidin in pharmaceutical forms was obtained in the range from 0.05 to 10.00 mu g mL(-1). The LOD was 0.01 mu g mL(-1) and the LOQ was 0.03 mu g mL(-1). The linearity range for the determination of hesperidin in plasma was 0.02-10.00 mu g mL(-1) with an LOD 0.005 mu g mL(-1) and an LOQ of 0.015 mu g mL(-1). The good agreement between the two methods indicates the usability of the proposed fluorometric method for the simple, precise and accurate determination of hesperidin in clinical and quality control laboratories.
PB  - Srpsko hemijsko društvo, Beograd
T2  - Journal of the Serbian Chemical Society
T1  - Development and validation of a fluorometric method for the determination of hesperidin in human plasma and pharmaceutical forms
EP  - 1640
IS  - 11
SP  - 1625
VL  - 77
DO  - 10.2298/JSC111005060P
ER  - 

@article{
author = "Pavun, Leposava A and Dimitrić-Marković, Jasmina and Djurdjević, Predrag T and Jelikic-Stankov, Milena D and Đikanović, Daniela and Ciric, Andrija and Malesev, Dusan L",
year = "2012",
abstract = "A fluorometric method, based on the fluorescence properties of the aluminium(III)-hesperidin complex, for the determination of hesperidin in human plasma and pharmaceutical forms has been developed and validated. The complex shows a strong emission in the presence of the surfactant betain sulphonate SB 12 at 476 nm with excitation at 390 nm. The linearity range for pharmaceutical forms of hesperidin was 0.06-24.4 mu g mL(-1) with a limit of detection, LOD, of 0.016 mu g mL(-1) and a limit of quantification, LOQ, of 0.049 mu g mL(-1). Recovery values in the range 99.3-99.7 % indicate good accuracy of the method. A linear dependence of the intensity of fluorescence of the complex on the concentration of hesperidin in plasma was obtained in concentration range from 0.1-12.2 mu g mL(-1). The LOD was 0.032 mu g mL(-1) while LOQ was 0.096 mu g mL(-1). Recovery values were in the range 98.4-99.8 %. The reliability of the method was checked by an LC MS/MS method for plasma samples and an HPLC/UV method for tablets with direct determination of hesperidin after separation. Linearity range in determination of hesperidin in pharmaceutical forms was obtained in the range from 0.05 to 10.00 mu g mL(-1). The LOD was 0.01 mu g mL(-1) and the LOQ was 0.03 mu g mL(-1). The linearity range for the determination of hesperidin in plasma was 0.02-10.00 mu g mL(-1) with an LOD 0.005 mu g mL(-1) and an LOQ of 0.015 mu g mL(-1). The good agreement between the two methods indicates the usability of the proposed fluorometric method for the simple, precise and accurate determination of hesperidin in clinical and quality control laboratories.",
publisher = "Srpsko hemijsko društvo, Beograd",
journal = "Journal of the Serbian Chemical Society",
title = "Development and validation of a fluorometric method for the determination of hesperidin in human plasma and pharmaceutical forms",
pages = "1640-1625",
number = "11",
volume = "77",
doi = "10.2298/JSC111005060P"
}

Pavun, L. A., Dimitrić-Marković, J., Djurdjević, P. T., Jelikic-Stankov, M. D., Đikanović, D., Ciric, A.,& Malesev, D. L.. (2012). Development and validation of a fluorometric method for the determination of hesperidin in human plasma and pharmaceutical forms. in Journal of the Serbian Chemical Society
Srpsko hemijsko društvo, Beograd., 77(11), 1625-1640.
https://doi.org/10.2298/JSC111005060P

Pavun LA, Dimitrić-Marković J, Djurdjević PT, Jelikic-Stankov MD, Đikanović D, Ciric A, Malesev DL. Development and validation of a fluorometric method for the determination of hesperidin in human plasma and pharmaceutical forms. in Journal of the Serbian Chemical Society. 2012;77(11):1625-1640.
doi:10.2298/JSC111005060P .

Pavun, Leposava A, Dimitrić-Marković, Jasmina, Djurdjević, Predrag T, Jelikic-Stankov, Milena D, Đikanović, Daniela, Ciric, Andrija, Malesev, Dusan L, "Development and validation of a fluorometric method for the determination of hesperidin in human plasma and pharmaceutical forms" in Journal of the Serbian Chemical Society, 77, no. 11 (2012):1625-1640,
https://doi.org/10.2298/JSC111005060P . .

TY  - JOUR
AU  - Pavun, Leposava
AU  - Đikanović, Daniela
AU  - Durdević, P.
AU  - Stankov, M.J.
AU  - Malešev, D.
AU  - Ćirić, A.
PY  - 2009
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/349
AB  - Morin is a flavonol antioxidant. In ethanol-water mixtures (70 wt% of ethanol) it reacts with Al3+ to give Al(Morin)(2) in the pH range 3-6. The conditional stability constant of this complex at 298 K was found to be log beta(2) = 16.96 +/- 0.02 at pH 4.40. The complex shows strong fluorescence emission at 500 nm upon excitation at 410 nm. The fluorescence intensity is pH dependent with maximum emission at pH 4.40. Since the complexation reaction enhances the fluorescence of morin, this property was used for the determination of morin in human serum. A linear dependence of the intensity of fluorescence of the complex on the concentration of morin was obtained in morin concentration range from 1.5-30.5 ng mL(-1), relative standard error of measurements was 1.4%. The LOD was 0.02 ng mL(-1) while LOQ was 1.0 ng mL(-1). Serum concentration of morin was also determined using HPLC as a reference method. A C-18 Hypersil Gold AQ column was used with acetonitrile-0.1% v/v phosphoric acid (30:70% v/v) as the mobile phase at 1.0 mL min(-1) flow rate and UV detection at 250 nm. Acceptable relative standard errors (less than 5%) between determinations obtained by the two methods indicate that the fluorescence method is reliable.
PB  - Slovenian Chemical Society
T2  - Acta Chimica Slovenica
T1  - Spectrofluorimetric and HPLC Determination of Morin in Human Serum
EP  - 972
IS  - 4
SP  - 967
VL  - 56
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_349
ER  - 

@article{
author = "Pavun, Leposava and Đikanović, Daniela and Durdević, P. and Stankov, M.J. and Malešev, D. and Ćirić, A.",
year = "2009",
abstract = "Morin is a flavonol antioxidant. In ethanol-water mixtures (70 wt% of ethanol) it reacts with Al3+ to give Al(Morin)(2) in the pH range 3-6. The conditional stability constant of this complex at 298 K was found to be log beta(2) = 16.96 +/- 0.02 at pH 4.40. The complex shows strong fluorescence emission at 500 nm upon excitation at 410 nm. The fluorescence intensity is pH dependent with maximum emission at pH 4.40. Since the complexation reaction enhances the fluorescence of morin, this property was used for the determination of morin in human serum. A linear dependence of the intensity of fluorescence of the complex on the concentration of morin was obtained in morin concentration range from 1.5-30.5 ng mL(-1), relative standard error of measurements was 1.4%. The LOD was 0.02 ng mL(-1) while LOQ was 1.0 ng mL(-1). Serum concentration of morin was also determined using HPLC as a reference method. A C-18 Hypersil Gold AQ column was used with acetonitrile-0.1% v/v phosphoric acid (30:70% v/v) as the mobile phase at 1.0 mL min(-1) flow rate and UV detection at 250 nm. Acceptable relative standard errors (less than 5%) between determinations obtained by the two methods indicate that the fluorescence method is reliable.",
publisher = "Slovenian Chemical Society",
journal = "Acta Chimica Slovenica",
title = "Spectrofluorimetric and HPLC Determination of Morin in Human Serum",
pages = "972-967",
number = "4",
volume = "56",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_349"
}

Pavun, L., Đikanović, D., Durdević, P., Stankov, M.J., Malešev, D.,& Ćirić, A.. (2009). Spectrofluorimetric and HPLC Determination of Morin in Human Serum. in Acta Chimica Slovenica
Slovenian Chemical Society., 56(4), 967-972.
https://hdl.handle.net/21.15107/rcub_rimsi_349

Pavun L, Đikanović D, Durdević P, Stankov M, Malešev D, Ćirić A. Spectrofluorimetric and HPLC Determination of Morin in Human Serum. in Acta Chimica Slovenica. 2009;56(4):967-972.
https://hdl.handle.net/21.15107/rcub_rimsi_349 .

Pavun, Leposava, Đikanović, Daniela, Durdević, P., Stankov, M.J., Malešev, D., Ćirić, A., "Spectrofluorimetric and HPLC Determination of Morin in Human Serum" in Acta Chimica Slovenica, 56, no. 4 (2009):967-972,
https://hdl.handle.net/21.15107/rcub_rimsi_349 .