Elektrohemijsko kvantitativno određivanje sertralina u farmaceutskim proizvodima na elektrod iod zlata u bikarbonatnom elektrolitu

The electrochemical characterization of sertraline standard at gold electrode was at first performed by cyclic voltammetry measurements (CV) in pH 8.4 bicarbonate buffer. Then Au electrode was evaluated for the quantitative determination of sertraline using square wave voltammetry (SWV). Namely, (2-hydroxypropyl)-β-cyclodextrin (HPβCD) sertraline inclusion complexe was employed to enhance the electrode sensitivity of the drug determination. Using the proposed SWV technique, the anodic current peak of sertraline oxidation was linear within a concentration range of 0.1–0.5 μM with a limit of detection (LOD) of 2.0 10-8 M and a limit of quantification (LOQ) of 6.7 10-8 M. In the case of inclusion complex of the sertraline with HPβCD, a good linearity range of 0.1–0.9 μM was obtained with a LOD of 2.6 10-8 M and a LOQ of 8.8 10-8 μM. Comparing the regression equations, it can be concluded that the sensitivity in the presence of inclusion complex can be up to 5 times higher. The applicability of the developed method was confirmed by the analysis of this drug in pharmaceutical formulation.Elektrohemijska karakterizacija standarda sertralina je urađena cikličnom voltametrijom(CV) u pH 8.4 bicarbonatnom puferu. Elektroda od zlata je zatim testirana za kvantitativno određivanje sertralina koristeći voltametriju sa pravougaonim impulsima (SWV). Inkluzioni kompleks (2-hydroxypropyl)-β-cyclodextrin (HPβCD) sertralina je testiran u cilju poboljšanja osetljivosti electrode za kvantitativno određivanje leka. SWV tehnikom je pokazano da je anodni strujni vrh oksidacije sertralina linearan u opsegu koncentracija 0.1–0.5 μM uz granicu detekcije (LOD) od 2.0 10-8 M i granicu kvantifikacije (LOQ) od 6.7 10-8 M. Inkluzioni kompleks sertralina sa HPβCD je ispoljio linearnost u opsegu koncentracija od 0.1–0.9 μM uz LOD of 2.6 10-8 M i LOQ od 8.8 10-8 μM. Analizom eksperimentalnih podataka može se zaklučiti da je osetljivost electrode od zlata za određivanje sertraline porasla više od pet puta kada je lek vezan u inkluzioni kompleks. Primenljivost razvijene metode je potvrđena uspešnim određivanjem leka u farmaceutskim oblicima

Elektrooksidacija smeše formaldehida i 2-propanola na monokristalima zlata orijentacije (100) i (111) u alkalnoj sredini

The effect of formaldehyde on the oxidation of 2-propanol and vice versa on gold single crystal planes (100 and 111) was studied. An activating effect in the reaction of the simultaneous oxidation of 2-propanol and formaldehyde was obtained on a gold (100) plane. In the case of a gold (111) electrode, the activation effect was not obtained. It was concluded that the adsorption of formaldehyde on the electrode surface prevents the adsorption of poisoning species formed during the electro-oxidation of 2-propanol on the Au(100) plane, while this is not the case on the Au(111) plane. The different behavior is caused by the difference in the symmetry of the surface atoms of these two Au single crystal planes. .Ispitivan je uticaj formaldehida na oksidaciju 2-propanola i vice versa na monokristalima zlata orijentacija (100) i (111). U reakciji simultane oksidacije 2-propanola i formaldehida na monokristalu zlata orijentacije (100) dobijen je aktivacioni efekat. Ovaj efekat nije dobijen na elektrodi od zlata orijentacije (111). Zaključeno je da prisustvo adsorbovanog formaldehida onemogućava adsorpciju čvrsto vezanih intermedijera formiranih tokom elektrooksidacije 2-propanola, koji se ponašaju kao otrovi za elektrodu, na ravni (100). Ovo nije slučaj na ravni (111). Različito ponašanje je uzrokovano razlikama u simetriji i energijama površinskih atoma na ove dve monokristalne ravni.

Elektroredukcija cefetameta na elektrodama od žive, platine i zlata

The electroreduction of cefetamet (CEF) using gold and platinum electrodes has been investigated in slightly alkaline medium (pH 8.40) where adsorption, previously observed at mercury electrode, was pronounced. This investigation was performed in order to determine whether the adsorption interferes with the reduction process even at solid electrodes and to compare with a mercury electrode.Redukcija cefetameta na elektrodama od zlata i platine je proučavana u slabo alkalnoj sredini (pH 8,40) gde je u prethodnim ispitivanjima na živinoj elektrodi u toku reakcije uočena adsorpcija antibiotika. Ovaj rad je posvećen ispitivanju uticaja adsorpcije na elektroredukciju cefetameta na čvrstim elektrodama i poređenju sa živom

Електрохемијска стабилност метформина у воденим растворима NaHCO3 И Na2SO4 на Au, GC и IrOx електродама

In this study the electrochemical behavior of metformin (MET), oral antihyperglycaemic agent, was assayed at three different electrodes. The drug standard was investigated by cyclic voltammetry (CV) and square wave volta-mmetry (SWV) via its electrooxidation at Au and glassy carbon (GC) electrode in 0.05 M NaHCO3. Under these conditions transformation of MET to corresponding N-carbonyl guanidine via oxime intermediate is suggested. The stability of MET was tested under directed stress conditions using IrOx elec-trode with sodium sulphate as an electrolyte and cyclic 4-amino-2-imino-1-me-thyl-1,2-dihydro-1,3,5-triazine (4,2,1-AIMT) appeared as the main end-product. The courses of the electrochemical processes at three electrodes are followed by UV spectroscopy and evaluated by total organic carbon (TOC) analysis.У оквиру рада изучавано је електрохемијско понашање метформина, лека са антихипергликемијским дејством, на три различите електроде. Стандард лека испитан је цикличном волтаметријом и волтаметријом са правоугаоним импулсима у 0,05 М раствору NaHCO3 на елекроди од злата и електроди од стакластог угљеника. Под овим условима, предложена је трансформација лека до одговарајућег N-карбонил гуанидина преко оксима као интермедијера. Стабилност метформина тестирана је и под условима електрохемијске оксидације на IrOx електроди у присуству натријум сулфата као електолита. У овом случају, предложено је настајање цикличног 4-амино-2-имино-1- метил-1,2-дихидро-1,3,5-триазина као главног производа. Ток електрохемијских процеса на све три електроде праћен је УВ спектроскопијом. Степен минерализације утврђен је анализом укупног органског угљеника.This is the peer-reviewed version of the article: Lović Jelena, Lađarević Jelena, Mijin Dušan, Jadranin Milka, Petrović Slobodan D., Avramov-Ivić Milka, Electrochemical stability of metformin in NaHCO3 and Na2SO4 water solution at Au, GC and IrOx electrodes, Journal of the Serbian Chemical Society 2019 Volume 84, Issue 11, Pages: 1319-1327 [https://doi.org/10.2298/JSC190731091L]The published version: [http://cer.ihtm.bg.ac.rs/handle/123456789/3383

Voltammetric Investigation of Inclusion Complexes of the Selected Succinimides with β-Cyclodextrin and (2-Hydroxypropyl)-β-Cyclodextrin

The inclusion complexes of the selected, potentially biologically active, succinimides with β-cyclodextrin (βCD) and (2-hydroxypropyl)-β-cyclodextrin (HPβCD) were prepared. the formation of the inclusion complexes of the investigated monophenyl and diphenyl succinimide derivatives was confirmed using attenuated total reflection (ATR) study. Their electrochemical behavior was examined by cyclic voltammetry (CV) and square wave voltammetry (SWV) in 0.05 M NaHCO3 on a gold electrode. The stability constants for compound 1 were determined by cyclic voltammetry and calculated as KβCD = 350.87 M–1 and KHPβCD = 250.67 M–1. The SWV measurements reveal well defined peak at potential Ep = ~ 60 mV and the higher currents at Ep for both inclusion complex of the succinimides compared to the free compounds. The impact of chlorine atom in the phenyl moiety of succinimide derivatives on the activity in electrooxidation reaction is presented. Among the studied succinimides, according to SWV measurements, the most active is the monophenyl succinimide derivative (compound 1) in complex with βCD. The difference of peak current of compound 1 + βCD compared to compound 1 + HPβCD and free compound is 6.3 and 35.2 μA cm–2, respectively

Electrochemical Characterization of Oxaprozin on Bare Gold Electrode and Electrode Modified with Bovine Serum Albumin

As the very first electrochemical investigation of oxaprozin, nonsteroidal anti-inflammatory drug, using cyclic voltammetry on gold electrode in 0.05 mol dm(-3) NaHCO3, the synthesized drug, its analytical standard and its content in Duraprox (R) tablets were characterized with one oxidation reaction and the three reduction reactions. All they exhibited the linear concentration dependency of anodic currents at 0.83V for the analytical standard and 0.85V for Duraprox (R) tablets in the range of concentrations 8.44 - 32.78x10(-6) mol dm(-3). The strong adsorption of bovine serum albumin (BSA) on gold electrode in 0.1 mol dm(-3) phosphate buffer solution (pH 7.4) is shown and concentration dependency of anodic currents of oxaprozin standard on BSA/Au is studied. Following the Langmuir adsorption thermodynamic equation, the binding constants of oxaprozin on BSA/Au electrode was calculated with the results 1.23x10(5) dm(3) mol(-1)

Racism and Patriarchy in the Meaning of Motherhood

The catalytic abilities of a gold electrode were tested for the quantitative determination of amphetamine (A) and 3,4-methylenedioxy-N-methylamphetamine (MDMA) standards by their oxidation using cyclic voltammetry (CV). The values of the oxidative currents of A and MDMA standards at 0.80 V vs. SCE in 0.05 M NaHCO3 at a scan rate of 50 mV s-1 were linear functions of the concentration in range of 110.9-258.9 μM and 38.7-229.2 μM, respectively. Square wave voltammetry (SWV) revealed a linear increase of current with the concentration of MDMA (range 30.9-91.6 μM), which enabled the quantitative determination of amphetamine derivates. SWV analysis was also successfully performed in spiked urine samples. A and MDMA in the presence of sucrose and as a content in illegally produced tablets were also determined. The voltammetric determinations of A and MDMA derivatives using CV and SWV at gold a electrode are rapid, selective and simple procedures and their accuracy was confirmed with a reference method, high performance liquid chromatography (HPLC). The analysis of spiked urine samples offers an additional possibility for the rapid detection of A and MDMA in human urine.Katalitička svojstva elektrode od zlata su testirana za kvantitativno određivanje amfetamina (A) i 3,4-metilendioksi-N-metilamfetamina (MDMA) standarda. Elektroksidacija A i MDMA je praćena cikličnom voltametrijom (CV). Vrednost oksidativnog pika A i MDMA standarda je linearna funkcija koncentracija u opsegu 110,9-258,9 μM (A) i 38,7-229,2 μM (MDMA). Voltametrija sa pravougaonim impulsima (SWV) je pokazala linearnu zavisnost struja od koncentracija za MDMA standard (u opsegu: 30,9-91,6 μM) kao i u spajkovanim uzorcima humanog urina. Uspešno je analiziran i sadržaj A i MDMA u ilegalno proizvedenim tabletama. Voltametrijsko određivanje A i MDMA derivata uz pomoć CV i SWV na elektrodi od zlata je brza, selektivna i jednostavna procedura. Analiza spajkovanih uzoraka urina nudi dodatnu mogućnost za brzu detekciju A i MDMA u humanom urinu

Voltammetric and Square-Wave Anodic Stripping Determination of Amlodipine Besylate on Gold Electrode

The oxidative behaviour of amlodipine besylate was studied. The gold electrode and Au/o-MWCNT (oxidized multi-wall carbon nanotubes) were used for determination of amlodipine besylate standard and as a content of Alopres tablet, in 0.05 M NaHCO3 and in phosphate buffer (pH=11) by cyclic voltammetry and square-wave anodic stripping voltammetry. Electrode surfaces were characterized by AFM in the presence of amlodipine and the concentrations of drugs in electrolytes were simultaneously followed by HPLC. The linear dependency of the anodic currents of amlodipine besylate as standard and in Alopres tablet vs. concentration was observed in both electrolytes, but in phosphate buffer for the higher concentrations. The peak currents obtained in all experiments are more than fifty-fold higher comparing to all previously published results concerning the glassy carbon electrode and the carbon paste electrode. The gold electrode is better catalyst for anodic oxidation of amlodipine besylate than glassy carbone. The results obtained with Au/o-MWCNT show lower anodic activity comparing to previously published GC/o-MWCNT. GC/o-MWCNT is better catalyst than Au/o-MWCNT under similar experimental conditions

The electrochemical investigation of inclusion complexes of nifedipine and amlodipine with ß-cyclodextrin and (2-hydroxypropyl)-ß-cyclodextrin

The electrochemical behavior of inclusion complexes of nifedipine (Nif) and amlodipine (Aml), a long-acting calcium channel blockers dihydropyridine (DHP) class, with ß-cyclodextrin (ßCD) and (2-hydroxypropyl)-ß-cyclodextrin (HPßCD), is examined using cyclic and square wave voltammetry in 0.05 M NaHCO3 and phosphate buffer (pH=11) on a gold electrode. The voltammograms show a single irreversible anodic wave with the current controlled by adsorption. It was found that phosphate buffer favorites the electrochemical activity of both complexes of Nif with the linear dependency of the oxidative currents on their concentrations. In phosphate buffer, only HPßCD-Aml complex showed linear dependency of the oxidative currents on the concentration. In 0.05 M NaHCO3 as electrolyte only HPßCD-Nif exhibited apparent activity. The initial potential of the anodic reaction as well as the value of the potential for anodic currents maximum of all the examined complexes in both electrolytes were shifted to the positive direction compared to their standards. In addition, the value of anodic currents decreased

Electrochemical determination of duloxetine hydrochloride at gold electrode

Duloxetine hydrochloride ( D U L ) , a naphth) I ether amine, inhibits the uptake of serotonin and norepinephrine. The electrochemical behavior of D U L was determined by cyclic voltammetry ( C V ) in phosphate buffer solution at gold electrode by varying pH and scan rate. The electroanalytical application was studied with the aid of differential pulse voltammetry (DPV) in sodium bicarbonate solution. A linear response ranged from 5x10'^ M to 10'" M. The validation of the DPV method was carried out by determine of the limit of detection (LOD) and limit of quantitation (LOQ) and the calculate values were 4.6 X 10"'' and 2 x 10'^' M, respective!). The proposed DPV method has been successfully applied to assessment DUL as standard and in Taita® tablets and standard spiked with human serum