TY  - JOUR
AU  - Avramov-Ivić, Milka
AU  - Lović, Jelena
AU  - Stevanović, Sanja
AU  - Nikolić, Nebojša
AU  - Trišović, Nemanja
AU  - Lađarević, Jelena
AU  - Vuković, Dragan
AU  - Drmanić, Saša
AU  - Mladenović, Aleksandar R.
AU  - Jadranin, Milka
AU  - Petrović, Slobodan
AU  - Mijin, Dušan
PY  - 2019
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4306
AB  - Esomeprazole is the most effective of the proton-pump inhibitors for the acid-related diseases and at first was examined for the electroanalytical purposes. The drug standard and as a content of injection powder was investigated by cyclic voltammetry (CV) and quantitatively determined using square wave voltammetry (SWV) via its electrooxidation at Au electrode in 0.05 M NaHCO3. SWV showed a linear dependency of the anodic peak currents vs. esomeprazole standard concentrations in the range from 3.0 to 500 mu g mL(-1) with the values of limit of detection (LOD) and limit of quantification (LOQ): 1.4 and 4.6 mu g mL(-1), respectively. Using the constructed and validated calibration curve, the values of unknown esomeprazole concentrations in injection powder and in human serum spiked with standard were determined. Before the electrochemical oxidation, it was shown by atomic force microscopy (AFM) that the small esomeprazole islands formed inside holes were visible and their diameter was about 200 nm attributed to physico-chemical characteristics of esomeprazole. After the electrochemical oxidation, the morphology of esomeprazole standard on Au surface was completely changed and composed of spherical particles in a diameter between 200 and 600 nm. With esomeprazole suspended in human serum, the process of crystallization partly occurred in the form of spherical grains with the average size of these grains was about 4 gm. The analysis at the macro level done by the optical microscopy (OM) confirmed this opinion. The study of esomeprazole degradation showed that at Au electrode, after 3 h of cycling, a neglectable amount of the esomeprazole was changed. Using IrOx electrode under directed stress conditions, its almost complete degradation was realized after 3 h confirmed by high performance liquid chromatography (HPLC). Total organic carbon (TOC) analysis showed that 95% of esomeprazole was mineralized. The HPLC and Liquid chromatography-mass spectrometry (LC-MS) study revealed the formation of 4-hydroxy omeprazole sulphide, 4-hydroxy omeprazole sulphone, esomeprazole sulphone and methylated esomeprazole.
PB  - Elsevier Science Sa, Lausanne
T2  - Journal of Electroanalytical Chemistry
T1  - Electrochemical behavior of esomeprazole: Its determination at Au electrode as standard and in injection powder combined with the study of its degradation
VL  - 848
DO  - 10.1016/j.jelechem.2019.113303
ER  - 

@article{
author = "Avramov-Ivić, Milka and Lović, Jelena and Stevanović, Sanja and Nikolić, Nebojša and Trišović, Nemanja and Lađarević, Jelena and Vuković, Dragan and Drmanić, Saša and Mladenović, Aleksandar R. and Jadranin, Milka and Petrović, Slobodan and Mijin, Dušan",
year = "2019",
abstract = "Esomeprazole is the most effective of the proton-pump inhibitors for the acid-related diseases and at first was examined for the electroanalytical purposes. The drug standard and as a content of injection powder was investigated by cyclic voltammetry (CV) and quantitatively determined using square wave voltammetry (SWV) via its electrooxidation at Au electrode in 0.05 M NaHCO3. SWV showed a linear dependency of the anodic peak currents vs. esomeprazole standard concentrations in the range from 3.0 to 500 mu g mL(-1) with the values of limit of detection (LOD) and limit of quantification (LOQ): 1.4 and 4.6 mu g mL(-1), respectively. Using the constructed and validated calibration curve, the values of unknown esomeprazole concentrations in injection powder and in human serum spiked with standard were determined. Before the electrochemical oxidation, it was shown by atomic force microscopy (AFM) that the small esomeprazole islands formed inside holes were visible and their diameter was about 200 nm attributed to physico-chemical characteristics of esomeprazole. After the electrochemical oxidation, the morphology of esomeprazole standard on Au surface was completely changed and composed of spherical particles in a diameter between 200 and 600 nm. With esomeprazole suspended in human serum, the process of crystallization partly occurred in the form of spherical grains with the average size of these grains was about 4 gm. The analysis at the macro level done by the optical microscopy (OM) confirmed this opinion. The study of esomeprazole degradation showed that at Au electrode, after 3 h of cycling, a neglectable amount of the esomeprazole was changed. Using IrOx electrode under directed stress conditions, its almost complete degradation was realized after 3 h confirmed by high performance liquid chromatography (HPLC). Total organic carbon (TOC) analysis showed that 95% of esomeprazole was mineralized. The HPLC and Liquid chromatography-mass spectrometry (LC-MS) study revealed the formation of 4-hydroxy omeprazole sulphide, 4-hydroxy omeprazole sulphone, esomeprazole sulphone and methylated esomeprazole.",
publisher = "Elsevier Science Sa, Lausanne",
journal = "Journal of Electroanalytical Chemistry",
title = "Electrochemical behavior of esomeprazole: Its determination at Au electrode as standard and in injection powder combined with the study of its degradation",
volume = "848",
doi = "10.1016/j.jelechem.2019.113303"
}

Avramov-Ivić, M., Lović, J., Stevanović, S., Nikolić, N., Trišović, N., Lađarević, J., Vuković, D., Drmanić, S., Mladenović, A. R., Jadranin, M., Petrović, S.,& Mijin, D.. (2019). Electrochemical behavior of esomeprazole: Its determination at Au electrode as standard and in injection powder combined with the study of its degradation. in Journal of Electroanalytical Chemistry
Elsevier Science Sa, Lausanne., 848.
https://doi.org/10.1016/j.jelechem.2019.113303

Avramov-Ivić M, Lović J, Stevanović S, Nikolić N, Trišović N, Lađarević J, Vuković D, Drmanić S, Mladenović AR, Jadranin M, Petrović S, Mijin D. Electrochemical behavior of esomeprazole: Its determination at Au electrode as standard and in injection powder combined with the study of its degradation. in Journal of Electroanalytical Chemistry. 2019;848.
doi:10.1016/j.jelechem.2019.113303 .

Avramov-Ivić, Milka, Lović, Jelena, Stevanović, Sanja, Nikolić, Nebojša, Trišović, Nemanja, Lađarević, Jelena, Vuković, Dragan, Drmanić, Saša, Mladenović, Aleksandar R., Jadranin, Milka, Petrović, Slobodan, Mijin, Dušan, "Electrochemical behavior of esomeprazole: Its determination at Au electrode as standard and in injection powder combined with the study of its degradation" in Journal of Electroanalytical Chemistry, 848 (2019),
https://doi.org/10.1016/j.jelechem.2019.113303 . .

TY  - JOUR
AU  - Radosavljević, Kristina D.
AU  - Golubović, Aleksandar
AU  - Radisić, M. M.
AU  - Mladenović, Aleksandar R.
AU  - Mijin, Dušan
AU  - Petrović, Slobodan
PY  - 2017
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3582
AB  - Nanocrystalline TiO2, synthesized by sol-gel route and characterized by XRPD, BET and SEM measurements, was applied in the photocatalytic degradation of amoxicillin, using an Osram Ultra-Vitalux (R) lamp as the light source. Amoxicillin is a semi-synthetic penicillin type antibiotic active against a wide range of gram-positive and a limited range of gram-negative organisms. The continuous release of antibiotics and their persistence in the environment may result in serious irreversible effects on aquatic and terrestrial organisms. Heterogeneous catalysis, which uses catalysts like TiO2, is a promising route for the degradation of organic pollutants including antibiotics. The effects of initial concentration of catalyst, initial salt concentration (NaCl and Na2SO4), ethanol and pH on the photocatalytic degradation of amoxicillin were studied. The mineralization of amoxicillin was analyzed by ion chromatography as well as by total organic ana-lysis. The catalytic properties of nanocrystalline TiO2 were compared to Evonik P25 catalyst.
PB  - Savez hemijskih inženjera, Beograd
T2  - Chemical Industry & Chemical Engineering Quarterly
T1  - Amoxicillin photodegradation by nanocrystalline tio2
EP  - 195
IS  - 2
SP  - 187
VL  - 23
DO  - 10.2298/CICEQ160122030R
ER  - 

@article{
author = "Radosavljević, Kristina D. and Golubović, Aleksandar and Radisić, M. M. and Mladenović, Aleksandar R. and Mijin, Dušan and Petrović, Slobodan",
year = "2017",
abstract = "Nanocrystalline TiO2, synthesized by sol-gel route and characterized by XRPD, BET and SEM measurements, was applied in the photocatalytic degradation of amoxicillin, using an Osram Ultra-Vitalux (R) lamp as the light source. Amoxicillin is a semi-synthetic penicillin type antibiotic active against a wide range of gram-positive and a limited range of gram-negative organisms. The continuous release of antibiotics and their persistence in the environment may result in serious irreversible effects on aquatic and terrestrial organisms. Heterogeneous catalysis, which uses catalysts like TiO2, is a promising route for the degradation of organic pollutants including antibiotics. The effects of initial concentration of catalyst, initial salt concentration (NaCl and Na2SO4), ethanol and pH on the photocatalytic degradation of amoxicillin were studied. The mineralization of amoxicillin was analyzed by ion chromatography as well as by total organic ana-lysis. The catalytic properties of nanocrystalline TiO2 were compared to Evonik P25 catalyst.",
publisher = "Savez hemijskih inženjera, Beograd",
journal = "Chemical Industry & Chemical Engineering Quarterly",
title = "Amoxicillin photodegradation by nanocrystalline tio2",
pages = "195-187",
number = "2",
volume = "23",
doi = "10.2298/CICEQ160122030R"
}

Radosavljević, K. D., Golubović, A., Radisić, M. M., Mladenović, A. R., Mijin, D.,& Petrović, S.. (2017). Amoxicillin photodegradation by nanocrystalline tio2. in Chemical Industry & Chemical Engineering Quarterly
Savez hemijskih inženjera, Beograd., 23(2), 187-195.
https://doi.org/10.2298/CICEQ160122030R

Radosavljević KD, Golubović A, Radisić MM, Mladenović AR, Mijin D, Petrović S. Amoxicillin photodegradation by nanocrystalline tio2. in Chemical Industry & Chemical Engineering Quarterly. 2017;23(2):187-195.
doi:10.2298/CICEQ160122030R .

Radosavljević, Kristina D., Golubović, Aleksandar, Radisić, M. M., Mladenović, Aleksandar R., Mijin, Dušan, Petrović, Slobodan, "Amoxicillin photodegradation by nanocrystalline tio2" in Chemical Industry & Chemical Engineering Quarterly, 23, no. 2 (2017):187-195,
https://doi.org/10.2298/CICEQ160122030R . .

TY  - JOUR
AU  - Radosavljević, Kristina D.
AU  - Lović, Jelena
AU  - Mijin, Dušan
AU  - Petrović, Slobodan
AU  - Jadranin, Milka
AU  - Mladenović, Aleksandar R.
AU  - Avramov-Ivić, Milka
PY  - 2017
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3685
AB  - The electrodegradation of azithromycin was studied by its indirect oxidation using dimensionally stable Ti/RuO2 anode as catalyst in the electrolyte containing methanol, 0.05 M NaHCO3, sodium chloride and deionized water. The optimal conditions for galvanostatic electrodegradation for the azithromycin concentration of 0.472 mg cm(-3) were found to be NaCl concentration of 7 mg cm(-3) and the applied current of 300 mA. The differential pulse voltammetry using glassy carbon electrode was performed for the first time in the above-mentioned content of electrolyte for the nine concentration of azithromycin (0.075-0.675 mg cm(-3)) giving the limits of azithromycin detection and of quantification as: LOD 0.044 mg cm(-3) and LOQ 0.145 mg cm(-3). The calibration curve was constructed enabling the electrolyte analysis during its electrodegradation process. The electrolyte was analyzed by high-performance liquid chromatography and electrospray ionization time-of-flight mass spectrometry. The electrooxidation products were identified and after 180 min there was no azithromycin in the electrolyte while TOC analysis showed that 79% of azithromycin was mineralized. The proposed degradation scheme is presented.
PB  - Springer International Publishing Ag, Cham
T2  - Chemical Papers
T1  - Degradation of azithromycin using Ti/RuO2 anode as catalyst followed by DPV, HPLC-UV and MS analysis
EP  - 1224
IS  - 7
SP  - 1217
VL  - 71
DO  - 10.1007/s11696-016-0115-2
ER  - 

@article{
author = "Radosavljević, Kristina D. and Lović, Jelena and Mijin, Dušan and Petrović, Slobodan and Jadranin, Milka and Mladenović, Aleksandar R. and Avramov-Ivić, Milka",
year = "2017",
abstract = "The electrodegradation of azithromycin was studied by its indirect oxidation using dimensionally stable Ti/RuO2 anode as catalyst in the electrolyte containing methanol, 0.05 M NaHCO3, sodium chloride and deionized water. The optimal conditions for galvanostatic electrodegradation for the azithromycin concentration of 0.472 mg cm(-3) were found to be NaCl concentration of 7 mg cm(-3) and the applied current of 300 mA. The differential pulse voltammetry using glassy carbon electrode was performed for the first time in the above-mentioned content of electrolyte for the nine concentration of azithromycin (0.075-0.675 mg cm(-3)) giving the limits of azithromycin detection and of quantification as: LOD 0.044 mg cm(-3) and LOQ 0.145 mg cm(-3). The calibration curve was constructed enabling the electrolyte analysis during its electrodegradation process. The electrolyte was analyzed by high-performance liquid chromatography and electrospray ionization time-of-flight mass spectrometry. The electrooxidation products were identified and after 180 min there was no azithromycin in the electrolyte while TOC analysis showed that 79% of azithromycin was mineralized. The proposed degradation scheme is presented.",
publisher = "Springer International Publishing Ag, Cham",
journal = "Chemical Papers",
title = "Degradation of azithromycin using Ti/RuO2 anode as catalyst followed by DPV, HPLC-UV and MS analysis",
pages = "1224-1217",
number = "7",
volume = "71",
doi = "10.1007/s11696-016-0115-2"
}

Radosavljević, K. D., Lović, J., Mijin, D., Petrović, S., Jadranin, M., Mladenović, A. R.,& Avramov-Ivić, M.. (2017). Degradation of azithromycin using Ti/RuO2 anode as catalyst followed by DPV, HPLC-UV and MS analysis. in Chemical Papers
Springer International Publishing Ag, Cham., 71(7), 1217-1224.
https://doi.org/10.1007/s11696-016-0115-2

Radosavljević KD, Lović J, Mijin D, Petrović S, Jadranin M, Mladenović AR, Avramov-Ivić M. Degradation of azithromycin using Ti/RuO2 anode as catalyst followed by DPV, HPLC-UV and MS analysis. in Chemical Papers. 2017;71(7):1217-1224.
doi:10.1007/s11696-016-0115-2 .

Radosavljević, Kristina D., Lović, Jelena, Mijin, Dušan, Petrović, Slobodan, Jadranin, Milka, Mladenović, Aleksandar R., Avramov-Ivić, Milka, "Degradation of azithromycin using Ti/RuO2 anode as catalyst followed by DPV, HPLC-UV and MS analysis" in Chemical Papers, 71, no. 7 (2017):1217-1224,
https://doi.org/10.1007/s11696-016-0115-2 . .

TY  - JOUR
AU  - Lović, Jelena
AU  - Trišović, Nemanja
AU  - Antanasijević, Jelena
AU  - Nikolić, Nebojša
AU  - Stevanović, Sanja
AU  - Mijin, Dušan
AU  - Vuković, Dragan
AU  - Mladenović, Aleksandar R.
AU  - Petrović, Slobodan
AU  - Avramov-Ivić, Milka
PY  - 2016
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3312
AB  - Nonmedical use of sildenafil citrate (SC) requires new methods for drug determination in human serum and in tablets. SC as standard and in Sildena (R) tablets is determined by square wave voltammetry (SWV) in 0.1 M H2SO4 (harmful for human serum) at gold electrode in a range: (1 x 10(-3),1 x 10(-2), 0.1, 0.5,1) mu M and on cysteine (Cys) modified gold electrode (Au/Cys) in a range: (1 x 10(-3),1 x 10(-2), 0.05, 0.1) mu M. The presence of Cys causes two times larger peak currents and shifting of the incipient potential of the SC oxidation to 0.1 V in negative direction. A safe procedure for SC determination as standard and in Sildena (R) tablets spiked with human serum is developed by SWV at gold electrode in 0.05 M NaHCO3 (suitable for human liquids) in a range: (1 x 10(-3),1 x 10(-2), 0.1, 0.2, 03) mu M. Microscopic characterization of the surfaces morphology was also performed. The SC concentrations were checked by high performance liquid chromatography-ultraviolet spectroscopy (HPLC-UV) showing that electrochemical method is more sensitive and can be used for the measurements of very low concentrations of the analyte.
PB  - Elsevier Science Sa, Lausanne
T2  - Journal of Electroanalytical Chemistry
T1  - Electrochemical determination of sildenafil citrate as standard, in tablets and spiked with human serum at gold and cystein modified gold electrode
EP  - 107
SP  - 103
VL  - 782
DO  - 10.1016/j.jelechem.2016.10.022
ER  - 

@article{
author = "Lović, Jelena and Trišović, Nemanja and Antanasijević, Jelena and Nikolić, Nebojša and Stevanović, Sanja and Mijin, Dušan and Vuković, Dragan and Mladenović, Aleksandar R. and Petrović, Slobodan and Avramov-Ivić, Milka",
year = "2016",
abstract = "Nonmedical use of sildenafil citrate (SC) requires new methods for drug determination in human serum and in tablets. SC as standard and in Sildena (R) tablets is determined by square wave voltammetry (SWV) in 0.1 M H2SO4 (harmful for human serum) at gold electrode in a range: (1 x 10(-3),1 x 10(-2), 0.1, 0.5,1) mu M and on cysteine (Cys) modified gold electrode (Au/Cys) in a range: (1 x 10(-3),1 x 10(-2), 0.05, 0.1) mu M. The presence of Cys causes two times larger peak currents and shifting of the incipient potential of the SC oxidation to 0.1 V in negative direction. A safe procedure for SC determination as standard and in Sildena (R) tablets spiked with human serum is developed by SWV at gold electrode in 0.05 M NaHCO3 (suitable for human liquids) in a range: (1 x 10(-3),1 x 10(-2), 0.1, 0.2, 03) mu M. Microscopic characterization of the surfaces morphology was also performed. The SC concentrations were checked by high performance liquid chromatography-ultraviolet spectroscopy (HPLC-UV) showing that electrochemical method is more sensitive and can be used for the measurements of very low concentrations of the analyte.",
publisher = "Elsevier Science Sa, Lausanne",
journal = "Journal of Electroanalytical Chemistry",
title = "Electrochemical determination of sildenafil citrate as standard, in tablets and spiked with human serum at gold and cystein modified gold electrode",
pages = "107-103",
volume = "782",
doi = "10.1016/j.jelechem.2016.10.022"
}

Lović, J., Trišović, N., Antanasijević, J., Nikolić, N., Stevanović, S., Mijin, D., Vuković, D., Mladenović, A. R., Petrović, S.,& Avramov-Ivić, M.. (2016). Electrochemical determination of sildenafil citrate as standard, in tablets and spiked with human serum at gold and cystein modified gold electrode. in Journal of Electroanalytical Chemistry
Elsevier Science Sa, Lausanne., 782, 103-107.
https://doi.org/10.1016/j.jelechem.2016.10.022

Lović J, Trišović N, Antanasijević J, Nikolić N, Stevanović S, Mijin D, Vuković D, Mladenović AR, Petrović S, Avramov-Ivić M. Electrochemical determination of sildenafil citrate as standard, in tablets and spiked with human serum at gold and cystein modified gold electrode. in Journal of Electroanalytical Chemistry. 2016;782:103-107.
doi:10.1016/j.jelechem.2016.10.022 .

Lović, Jelena, Trišović, Nemanja, Antanasijević, Jelena, Nikolić, Nebojša, Stevanović, Sanja, Mijin, Dušan, Vuković, Dragan, Mladenović, Aleksandar R., Petrović, Slobodan, Avramov-Ivić, Milka, "Electrochemical determination of sildenafil citrate as standard, in tablets and spiked with human serum at gold and cystein modified gold electrode" in Journal of Electroanalytical Chemistry, 782 (2016):103-107,
https://doi.org/10.1016/j.jelechem.2016.10.022 . .

TY  - JOUR
AU  - Mladenović, Aleksandar R.
AU  - Jadranin, Milka
AU  - Pavlović, Aleksandar D.
AU  - Petrović, Slobodan
AU  - Drmanić, Saša
AU  - Avramov-Ivić, Milka
AU  - Mijin, Dušan
PY  - 2015
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/2927
AB  - This study describes the investigation of degradation products of donepezil (DP) using a stability-indicating RP-HPLC method for determination of donepezil, which is a centrally acting reversible acetyl cholinesterase inhibitor. In order to investigate the stability of the drug and formed degradation products, a forced degradation study of the drug sample and finished product under different forced degradation conditions was conducted. Donepezil hydrochloride and donepezil tablets were subjected to stress degradation conditions recommended by the International Conference on Harmonization (ICH). Donepezil hydrochloride solutions were subjected to acid and alkali hydrolysis, chemical oxidation and thermal degradation. Significant degradation was observed under alkali hydrolysis and oxidative degradation conditions. Additional degradation products were observed under the conditions of oxidative degradation. The degradation products observed during forced degradation studies were monitored using the developed high performance liquid chromatography (HPLC) method. The parent method was modified in order to obtain LC-MS compatible method, which was used to identify the degradation products from forced degradation samples using high resolution mass spectrometry. The mass spectrum provided the precise mass from which the molecular formula of the drug substance and formed degradation products was derived, and proved the specificity of the method unambiguously.
AB  - Proučavanje degradacionih proizvoda donepezila je izvršeno korišćenjem RP-HPLC metode za određivanje stabilnosti donepezila, leka koji pripada grupi reverzibilnih inhibitora acetilholinesteraze. U cilju ispitivanja stabilnosti leka i njegovih degradacionih proizvoda sprovedena je studija forsirane degradacije čiste supstance kao i farmaceutskog proizvoda pod različitim uslovima. Donepezil-hidrohlorid i donepezil tablete su podvrgnuti različitim uslovima degradacije prema preporukama Internacionalne konferencije za harmonizaciju. Rastvori donepezil-hidrohlorida su podvrgnuti kiseloj i baznoj hidrolizi, hemijskoj oksidaciji i termalnoj degradaciji. Pri baznoj hidrolizi i hemijskoj oksidaciji uočena je značajna degradacija polaznog molekula. Oksidativnom degradacijom nastaju i proizvodi koji nisu uočeni kod ostalih postupaka forsirane degradacije. Nastali proizvodi analizirani su novorazvijenom HPLC metodom. Osnovna metoda je modifikovana u cilju dobijanja LC-MS kompatibilne metode kako bi se identifikovali nastali degradacioni proizvodi. Na osnovu resultata dobijenih masenom spektrometrijom dobijene su tačne mase proizvoda degradacije, čime je omogućeno određivanje njihovih molekulskih formula.
PB  - Association of the Chemical Engineers of Serbia
T2  - Chemical Industry & Chemical Engineering Quarterly
T1  - Liquid chromatography and liquid chromatography-mass spectrometry analysis of donepezil degradation products
T1  - Analiza degradacionih proizvoda donepezila primenom tečne hromatografije i tečne hromatografije-masene spektrometrije
EP  - 455
IS  - 3
SP  - 447
VL  - 21
DO  - 10.2298/CICEQ141023047M
ER  - 

@article{
author = "Mladenović, Aleksandar R. and Jadranin, Milka and Pavlović, Aleksandar D. and Petrović, Slobodan and Drmanić, Saša and Avramov-Ivić, Milka and Mijin, Dušan",
year = "2015",
abstract = "This study describes the investigation of degradation products of donepezil (DP) using a stability-indicating RP-HPLC method for determination of donepezil, which is a centrally acting reversible acetyl cholinesterase inhibitor. In order to investigate the stability of the drug and formed degradation products, a forced degradation study of the drug sample and finished product under different forced degradation conditions was conducted. Donepezil hydrochloride and donepezil tablets were subjected to stress degradation conditions recommended by the International Conference on Harmonization (ICH). Donepezil hydrochloride solutions were subjected to acid and alkali hydrolysis, chemical oxidation and thermal degradation. Significant degradation was observed under alkali hydrolysis and oxidative degradation conditions. Additional degradation products were observed under the conditions of oxidative degradation. The degradation products observed during forced degradation studies were monitored using the developed high performance liquid chromatography (HPLC) method. The parent method was modified in order to obtain LC-MS compatible method, which was used to identify the degradation products from forced degradation samples using high resolution mass spectrometry. The mass spectrum provided the precise mass from which the molecular formula of the drug substance and formed degradation products was derived, and proved the specificity of the method unambiguously., Proučavanje degradacionih proizvoda donepezila je izvršeno korišćenjem RP-HPLC metode za određivanje stabilnosti donepezila, leka koji pripada grupi reverzibilnih inhibitora acetilholinesteraze. U cilju ispitivanja stabilnosti leka i njegovih degradacionih proizvoda sprovedena je studija forsirane degradacije čiste supstance kao i farmaceutskog proizvoda pod različitim uslovima. Donepezil-hidrohlorid i donepezil tablete su podvrgnuti različitim uslovima degradacije prema preporukama Internacionalne konferencije za harmonizaciju. Rastvori donepezil-hidrohlorida su podvrgnuti kiseloj i baznoj hidrolizi, hemijskoj oksidaciji i termalnoj degradaciji. Pri baznoj hidrolizi i hemijskoj oksidaciji uočena je značajna degradacija polaznog molekula. Oksidativnom degradacijom nastaju i proizvodi koji nisu uočeni kod ostalih postupaka forsirane degradacije. Nastali proizvodi analizirani su novorazvijenom HPLC metodom. Osnovna metoda je modifikovana u cilju dobijanja LC-MS kompatibilne metode kako bi se identifikovali nastali degradacioni proizvodi. Na osnovu resultata dobijenih masenom spektrometrijom dobijene su tačne mase proizvoda degradacije, čime je omogućeno određivanje njihovih molekulskih formula.",
publisher = "Association of the Chemical Engineers of Serbia",
journal = "Chemical Industry & Chemical Engineering Quarterly",
title = "Liquid chromatography and liquid chromatography-mass spectrometry analysis of donepezil degradation products, Analiza degradacionih proizvoda donepezila primenom tečne hromatografije i tečne hromatografije-masene spektrometrije",
pages = "455-447",
number = "3",
volume = "21",
doi = "10.2298/CICEQ141023047M"
}

Mladenović, A. R., Jadranin, M., Pavlović, A. D., Petrović, S., Drmanić, S., Avramov-Ivić, M.,& Mijin, D.. (2015). Liquid chromatography and liquid chromatography-mass spectrometry analysis of donepezil degradation products. in Chemical Industry & Chemical Engineering Quarterly
Association of the Chemical Engineers of Serbia., 21(3), 447-455.
https://doi.org/10.2298/CICEQ141023047M

Mladenović AR, Jadranin M, Pavlović AD, Petrović S, Drmanić S, Avramov-Ivić M, Mijin D. Liquid chromatography and liquid chromatography-mass spectrometry analysis of donepezil degradation products. in Chemical Industry & Chemical Engineering Quarterly. 2015;21(3):447-455.
doi:10.2298/CICEQ141023047M .

Mladenović, Aleksandar R., Jadranin, Milka, Pavlović, Aleksandar D., Petrović, Slobodan, Drmanić, Saša, Avramov-Ivić, Milka, Mijin, Dušan, "Liquid chromatography and liquid chromatography-mass spectrometry analysis of donepezil degradation products" in Chemical Industry & Chemical Engineering Quarterly, 21, no. 3 (2015):447-455,
https://doi.org/10.2298/CICEQ141023047M . .

TY  - JOUR
AU  - Pavlović, Aleksandar D.
AU  - Ignjatović, Ljubiša M.
AU  - Popov, Saša Z.
AU  - Mladenović, Aleksandar R.
AU  - Stanković, Igor N.
PY  - 2014
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/5761
AB  - A direct-injection, split-mode capillary gas chromatographic procedure with flame ionization detection was developed for the analysis of eight solvents used in the synthesis and purification of the anti-thrombotic drug clopidogrel bisulfate. The solvents analyzed were methanol, acetone, dichloromethane (DCM), 2-butanol, cyclohexane, toluene, acetic acid and N, N-dimethylformamide (DMF). In addition, because of dehydration of 2-butanol during the drying process, significant amounts of 2-butanol dehydration products (1-butene, cis- and trans-isomers of 2-butene, 2,2-oxybis[butane] and 1-(1- -methylpropoxy)butane) may be detected in clopidogrel bisulfate samples. The content of each of these volatile products can be evaluated using the same gaschromatographic method, with quantification based on the response factor established for the chromatographic peak of 2-butanol. Based on a large number of result sets, retrospectively, from many different batches analyzed, conclusions were made about process variations and reliability and a lack of consistency was identified in the quality of the active substance from a particular producer source. Multivariate analysis was used as the statistical technique to classify the samples. From the analyzed set of 11 solvents, 6 of them were preselected based upon their occurrence in the samples and both Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were performed.
PB  - Serbian Chemical Society
T2  - Journal of the Serbian Chemical Society
T1  - Application of gas chromatography analysis to quality control of residual organic solvents in clopidogrel bisulfate
EP  - 1293
IS  - 10
SP  - 1279
VL  - 79
DO  - 10.2298/JSC131120013P
ER  - 

@article{
author = "Pavlović, Aleksandar D. and Ignjatović, Ljubiša M. and Popov, Saša Z. and Mladenović, Aleksandar R. and Stanković, Igor N.",
year = "2014",
abstract = "A direct-injection, split-mode capillary gas chromatographic procedure with flame ionization detection was developed for the analysis of eight solvents used in the synthesis and purification of the anti-thrombotic drug clopidogrel bisulfate. The solvents analyzed were methanol, acetone, dichloromethane (DCM), 2-butanol, cyclohexane, toluene, acetic acid and N, N-dimethylformamide (DMF). In addition, because of dehydration of 2-butanol during the drying process, significant amounts of 2-butanol dehydration products (1-butene, cis- and trans-isomers of 2-butene, 2,2-oxybis[butane] and 1-(1- -methylpropoxy)butane) may be detected in clopidogrel bisulfate samples. The content of each of these volatile products can be evaluated using the same gaschromatographic method, with quantification based on the response factor established for the chromatographic peak of 2-butanol. Based on a large number of result sets, retrospectively, from many different batches analyzed, conclusions were made about process variations and reliability and a lack of consistency was identified in the quality of the active substance from a particular producer source. Multivariate analysis was used as the statistical technique to classify the samples. From the analyzed set of 11 solvents, 6 of them were preselected based upon their occurrence in the samples and both Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were performed.",
publisher = "Serbian Chemical Society",
journal = "Journal of the Serbian Chemical Society",
title = "Application of gas chromatography analysis to quality control of residual organic solvents in clopidogrel bisulfate",
pages = "1293-1279",
number = "10",
volume = "79",
doi = "10.2298/JSC131120013P"
}

Pavlović, A. D., Ignjatović, L. M., Popov, S. Z., Mladenović, A. R.,& Stanković, I. N.. (2014). Application of gas chromatography analysis to quality control of residual organic solvents in clopidogrel bisulfate. in Journal of the Serbian Chemical Society
Serbian Chemical Society., 79(10), 1279-1293.
https://doi.org/10.2298/JSC131120013P

Pavlović AD, Ignjatović LM, Popov SZ, Mladenović AR, Stanković IN. Application of gas chromatography analysis to quality control of residual organic solvents in clopidogrel bisulfate. in Journal of the Serbian Chemical Society. 2014;79(10):1279-1293.
doi:10.2298/JSC131120013P .

Pavlović, Aleksandar D., Ignjatović, Ljubiša M., Popov, Saša Z., Mladenović, Aleksandar R., Stanković, Igor N., "Application of gas chromatography analysis to quality control of residual organic solvents in clopidogrel bisulfate" in Journal of the Serbian Chemical Society, 79, no. 10 (2014):1279-1293,
https://doi.org/10.2298/JSC131120013P . .

TY  - JOUR
AU  - Mladenović, Aleksandar R.
AU  - Mijin, Dušan
AU  - Drmanić, Saša
AU  - Vajs, Vlatka
AU  - Jovanović, Vladislava M.
AU  - Petrović, Slobodan
AU  - Avramov-Ivić, Milka
PY  - 2014
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/2820
AB  - The oxidative ability of donepezil, a frequently prescribed drug for the treatment of Alzheimer's disease is reported for the first time at a gold electrode. It was oxidized by cyclic voltammetry and determined by square wave voltammetry in phosphate buffer electrolyte. Electrochemical degradation of donepezil was carried out by long term potential cycling. The identification and characterization of the major product, isolated by preparative high performance liquid chromatography, was performed by high resolution mass spectrometry and 1D and 2D nuclear magnetic resonance spectroscopy. Donepezil hydroxy derivative was identified as the major electrochemical oxidation product from donepezil.
PB  - Wiley-VCH Verlag Gmbh, Weinheim
T2  - Electroanalysis
T1  - Electrochemical Oxidation of Donepezil and Its Voltammetric Determination at Gold Electrode
EP  - 897
IS  - 5
SP  - 893
VL  - 26
DO  - 10.1002/elan.201400034
ER  - 

@article{
author = "Mladenović, Aleksandar R. and Mijin, Dušan and Drmanić, Saša and Vajs, Vlatka and Jovanović, Vladislava M. and Petrović, Slobodan and Avramov-Ivić, Milka",
year = "2014",
abstract = "The oxidative ability of donepezil, a frequently prescribed drug for the treatment of Alzheimer's disease is reported for the first time at a gold electrode. It was oxidized by cyclic voltammetry and determined by square wave voltammetry in phosphate buffer electrolyte. Electrochemical degradation of donepezil was carried out by long term potential cycling. The identification and characterization of the major product, isolated by preparative high performance liquid chromatography, was performed by high resolution mass spectrometry and 1D and 2D nuclear magnetic resonance spectroscopy. Donepezil hydroxy derivative was identified as the major electrochemical oxidation product from donepezil.",
publisher = "Wiley-VCH Verlag Gmbh, Weinheim",
journal = "Electroanalysis",
title = "Electrochemical Oxidation of Donepezil and Its Voltammetric Determination at Gold Electrode",
pages = "897-893",
number = "5",
volume = "26",
doi = "10.1002/elan.201400034"
}

Mladenović, A. R., Mijin, D., Drmanić, S., Vajs, V., Jovanović, V. M., Petrović, S.,& Avramov-Ivić, M.. (2014). Electrochemical Oxidation of Donepezil and Its Voltammetric Determination at Gold Electrode. in Electroanalysis
Wiley-VCH Verlag Gmbh, Weinheim., 26(5), 893-897.
https://doi.org/10.1002/elan.201400034

Mladenović AR, Mijin D, Drmanić S, Vajs V, Jovanović VM, Petrović S, Avramov-Ivić M. Electrochemical Oxidation of Donepezil and Its Voltammetric Determination at Gold Electrode. in Electroanalysis. 2014;26(5):893-897.
doi:10.1002/elan.201400034 .

Mladenović, Aleksandar R., Mijin, Dušan, Drmanić, Saša, Vajs, Vlatka, Jovanović, Vladislava M., Petrović, Slobodan, Avramov-Ivić, Milka, "Electrochemical Oxidation of Donepezil and Its Voltammetric Determination at Gold Electrode" in Electroanalysis, 26, no. 5 (2014):893-897,
https://doi.org/10.1002/elan.201400034 . .

TY  - JOUR
AU  - Mladenović, Aleksandar R.
AU  - Jovanović, Vladislava M.
AU  - Petrović, Slobodan
AU  - Mijin, Dušan
AU  - Drmanić, Saša
AU  - Avramov-Ivić, Milka
PY  - 2013
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/2351
AB  - The determination of clopidogrel, an antiplatelet agent, was performed at a gold electrode in pH 3.7 acetate buffer using cyclic voltammetry (CV) and square wave voltammetry (SWV). Each voltammogram was characterized by the well defined peak at approximately 1.0 V. The current of anodic stripping peak exhibited a linear dependence on the clopidogrel concentration in the range from 317.89 to 935.16 μg cm-3. The obtained linearity was applied to determine clopidogrel in the tablet form of the pharmaceutical preparation (Plavix®). The results were compared to the UV spectrophotometric and HPLC methods. .
AB  - Klopidogrel je antitrombotski agens iz tijenopiridinske klase, koji se koristi za inhibiranje formiranja krvnih ugrušaka pri lečenju koronarne arterijske bolesti, periferne vaskularne bolesti, i cerebrovaskularne bolesti. Elektrohemijsko ponašanje klopidogrel standarda i kao sastojka tablete Plavix® je definisano cikličnom voltametrijom. Njihovo kvantitativno određivanje na elektrodi od zlata u acetatnom puferu, pH 3,7, urađeno je voltametrijom sa pravougaonim impulsima (SWV). Pokazano je obema tehnikama da je svaki voltamogram okarakterisan dobro definisanim strujnim vrhom na 1,0 V. Na osnovu linearne zavisnosti anodnih struja od koncentracije klopidogrel standarda određena je masa klopidogrela u Plavix® tableti. Dobijeni rezultati pokazuju da SWV tehnika može biti korišćena direktno, brzo i jednostavno za određivanje klopidogrela u tabletama. Rezultati dobijeni SWV voltametrijskom tehnikom su poređeni sa rezultatima analize klopidogrela UV spektrofotometrijom i tečnom hromatografijom sa visokim performansama. Analitički rezultati pokazuju da je masa aktivne supstance u tabletama Plavix® u okviru limita specifikovanog farmakopejom. To ukazuje da voltametrija sa pravougaonim impulsima može biti uspešna alternativa hromatografskim i spektrofotometrijskim metodama. .
PB  - Serbian Chemical Society, Belgrade
T2  - Journal of the Serbian Chemical Society
T1  - Determination of clopidogrel using square wave voltammetry at a gold electrode
T1  - Određivanje klopidogrela voltametrijom sa pravouglim impulsima na elektrodi od zlata
EP  - 2140
IS  - 12
SP  - 2131
VL  - 78
UR  - https://hdl.handle.net/21.15107/rcub_technorep_2351
ER  - 

@article{
author = "Mladenović, Aleksandar R. and Jovanović, Vladislava M. and Petrović, Slobodan and Mijin, Dušan and Drmanić, Saša and Avramov-Ivić, Milka",
year = "2013",
abstract = "The determination of clopidogrel, an antiplatelet agent, was performed at a gold electrode in pH 3.7 acetate buffer using cyclic voltammetry (CV) and square wave voltammetry (SWV). Each voltammogram was characterized by the well defined peak at approximately 1.0 V. The current of anodic stripping peak exhibited a linear dependence on the clopidogrel concentration in the range from 317.89 to 935.16 μg cm-3. The obtained linearity was applied to determine clopidogrel in the tablet form of the pharmaceutical preparation (Plavix®). The results were compared to the UV spectrophotometric and HPLC methods. ., Klopidogrel je antitrombotski agens iz tijenopiridinske klase, koji se koristi za inhibiranje formiranja krvnih ugrušaka pri lečenju koronarne arterijske bolesti, periferne vaskularne bolesti, i cerebrovaskularne bolesti. Elektrohemijsko ponašanje klopidogrel standarda i kao sastojka tablete Plavix® je definisano cikličnom voltametrijom. Njihovo kvantitativno određivanje na elektrodi od zlata u acetatnom puferu, pH 3,7, urađeno je voltametrijom sa pravougaonim impulsima (SWV). Pokazano je obema tehnikama da je svaki voltamogram okarakterisan dobro definisanim strujnim vrhom na 1,0 V. Na osnovu linearne zavisnosti anodnih struja od koncentracije klopidogrel standarda određena je masa klopidogrela u Plavix® tableti. Dobijeni rezultati pokazuju da SWV tehnika može biti korišćena direktno, brzo i jednostavno za određivanje klopidogrela u tabletama. Rezultati dobijeni SWV voltametrijskom tehnikom su poređeni sa rezultatima analize klopidogrela UV spektrofotometrijom i tečnom hromatografijom sa visokim performansama. Analitički rezultati pokazuju da je masa aktivne supstance u tabletama Plavix® u okviru limita specifikovanog farmakopejom. To ukazuje da voltametrija sa pravougaonim impulsima može biti uspešna alternativa hromatografskim i spektrofotometrijskim metodama. .",
publisher = "Serbian Chemical Society, Belgrade",
journal = "Journal of the Serbian Chemical Society",
title = "Determination of clopidogrel using square wave voltammetry at a gold electrode, Određivanje klopidogrela voltametrijom sa pravouglim impulsima na elektrodi od zlata",
pages = "2140-2131",
number = "12",
volume = "78",
url = "https://hdl.handle.net/21.15107/rcub_technorep_2351"
}

Mladenović, A. R., Jovanović, V. M., Petrović, S., Mijin, D., Drmanić, S.,& Avramov-Ivić, M.. (2013). Determination of clopidogrel using square wave voltammetry at a gold electrode. in Journal of the Serbian Chemical Society
Serbian Chemical Society, Belgrade., 78(12), 2131-2140.
https://hdl.handle.net/21.15107/rcub_technorep_2351

Mladenović AR, Jovanović VM, Petrović S, Mijin D, Drmanić S, Avramov-Ivić M. Determination of clopidogrel using square wave voltammetry at a gold electrode. in Journal of the Serbian Chemical Society. 2013;78(12):2131-2140.
https://hdl.handle.net/21.15107/rcub_technorep_2351 .

Mladenović, Aleksandar R., Jovanović, Vladislava M., Petrović, Slobodan, Mijin, Dušan, Drmanić, Saša, Avramov-Ivić, Milka, "Determination of clopidogrel using square wave voltammetry at a gold electrode" in Journal of the Serbian Chemical Society, 78, no. 12 (2013):2131-2140,
https://hdl.handle.net/21.15107/rcub_technorep_2351 .