Browsing by Author "Inam, Recai"

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Citation Count: 14
Determination of Ophthalmic Drug Proparacaine Using Multi-walled Carbon Nanotube Paste Electrode by Square Wave Stripping Voltammetry
(Japan Soc Analytical Chemistry, 2018) Demir, Ersin; Inam, Onur; Inam, Recai
Proparacaine, one of the most common local anesthetics to facilitate diagnosis and treatment of eye diseases, was assayed by square wave voltammetry using a paste electrode prepared with carbon nanotubes. In cyclic voltammetric studies, proparacaine has exhibited a single irreversible anodic peak at around + 900 mV vs. Ag/AgCl in pH 6.0 Britton-Robinson buffer solution. It was suggested that the peak had appeared due to the oxidation of the NH2 group on the proparacaine molecule. Prior to the determination of the proparacaine by square wave stripping voltammetry (SWSV) on the fabricated multi-walled carbon nanotube paste electrode (MWCNTPE), the accumulation potential (E-acc), accumulation time (r.c), pulse amplitude (Delta E), step potential (Delta E-s) and frequency (f) parameters were optimized. The peak currents plotted in the range of 0.5 - 12.5 mg/L proparacaine exhibited two linear sections with a detection limit of 0.11 mg/L. The results for the determination of proparacaine on a pharmaceutical local anesthetic (Alcaine) showed that relative standard deviation (RSD) and relative error (RE) were 4.1 and 2.0%, respectively. Selectivity has also been investigated and results showed recoveries of 5.0 mg/L proparacaine in the presence of 5.0 mg/L dopamine, ascorbic acid and uric acid as 106.9 +/- 0.8, 99.9 +/- 1.2 and 94.1 +/- 0.7, respectively.
Citation Count: 8
Electro-Oxidation and Determination of Benomyl by Square-Wave Adsorptive Stripping Voltammetry
(Oxford Univ Press inc, 2014) Sarigul, Tuba; Inam, Recai; Demir, Ersin; Aboul-Enein, Hassan Y.
The electro-oxidation of the benomyl fungicide was studied by square-wave adsorptive stripping voltammetry. The voltammetric current at a glassy carbon electrode was acquired within the pH range 1.0-10.0. The quantitation was performed using the peak generated at +1144 mV by scanning the potential from +0.00 to +1600 mV (versus an Ag/AgCl reference electrode, 3 M NaCl). Accumulation potential = 0.0 mV, accumulation time=45 s, frequency=75 Hz, pulse amplitude=-60 mV, and staircase step potential =7 mV were used as square-wave parameters. The peak current versus concentrations plot were rectilinear over the range from 0.081 to 1.496 mu g/mL with an LOD of 0.024 mu g/mL. Mean recovery was 99.0% (0.198 +/- 0.011 mu g/mL), which was very close to the benomyl content spiked into river water (0.20 mu g/mL). The method was efficiently applied for benomyl determination in the pesticide formulation Minelate 50WG (R), and the average determined content of 49.8 +/- 0.16 (n = 5) was consistent with the 50% benomyl (w/w) quoted by the manufacturer. The benomyl voltammograms recorded between days exhibited a negligible degradation into carbendazim metabolite, and therefore all results were given as the total benomyl concentration. The high recoveries and low RSD gave evidence of good accuracy and precision.
Citation Count: 45
Electrochemical behavior of tadalafil on TiO₂ nanoparticles-MWCNT composite paste electrode and its determination in pharmaceutical dosage forms and human serum samples using adsorptive stripping square wave voltammetry
(Springer, 2014) Demir, Ersin; Inam, Recai; Ozkan, Sibel A.; Uslu, Bengi
A sensitive and selective electroanalytical method for the determination of tadalafil (TAD) using adsorptive stripping square wave voltammetry at multiwalled carbon nanotube paste electrode (MWCNTPE) and modified TiO2-multiwalled carbon nanotube paste electrode (TiO2-MWCNTPE) was presented. The calibration curves were linear in the concentration range of 3.6-8.1 and 12.7-61.1 mu M on MWCNTPE, 0.27-15.2 mu M on TiO2-MWCNTPE. The recommended method was successfully applied to the determination of the drug in tablets and human serum samples with good recoveries. The selectivity of the proposed method was considered in the presence of Ca2+, K+, Na+, 2-mercapto benzimidazole, thiourea, and dopamine by means of recovery tests. Interfering agents did not show considerable effect on TAD determination. No electroactive interferences from the tablet excipients and endogenous substances from biological material were detected. The possible electrooxidation pathway and the number of transferred electrons were also investigated.
Citation Count: 14
Electrochemical behaviour and determination of rimsulfuron herbicide by square wave voltammetry
(Taylor & Francis Ltd, 2014) Demir, Ersin; Inam, Recai
The voltammeric behaviour of rimsulfuron herbicide has been studied by square wave stripping voltammetry on static hanging mercury drop electrode. It exhibited a well-defined peak within the pH range of 1.0-6.0, having a maximum peak response at -600mV (vs.Ag/AgCl) at pH 3.0. The factors such as accumulation potential (E-acc), accumulation time (t(acc)), frequency (f), pulse amplitude (Delta E) and step potential (Delta E-s) have been optimised. The calibration plot was a straight line in the range of 4.4-134.4 mu gL(-1) with a detection limit of 1.3 mu gL(-1). The validity of the method was assessed from the recoveries of spiked lake water, tomato juice and agrochemical formulation of Doncep((R)). The results of the experiments conducted for five recoveries were 48.8 +/- 1.7 and 49.7 +/- 1.0 mu gL(-1), which are very close to the rimsulfuron spiked to lake water and tomato juice (50 mu gL(-1)), with a relative error of -2.4% and -0.6%, respectively. The electrode reaction mechanism was also postulated.
Citation Count: 6
Electrooxidation and determination of methacetin (p-acetanisidide) by square wave voltammetry using multiwalled carbon nanotube electrode
(Royal Soc Chemistry, 2013) Inam, Recai; Can, Eda; Demir, Ersin
A multiwall carbon nanotube paste electrode (MWCNTPE) was fabricated to investigate the detailed electrochemical behavior of methacetin and achieve its sensitive electroanalytical determination. The sensitive and selective square wave anodic peak seen at +1.06 V was linearly related to methacetin concentration in the range of 0.11 to 22.3 mg L-1 [0.665 to 135 mu M]. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.032 mg L-1 [0.193 mu M] and 0.11 mg L-1 [0.665 mu M], respectively. The percentage recovery of methacetin calculated from natural lake water samples spiked at the 5.0 mu g mL(-1) [30.3 mu M] level was 94.2% with a relative standard deviation of 0.21%. The considerably high recoveries and low standard deviations were evidence for the high accuracy and precision of the recommended method. The recovery of 10.0 mu g mL(-1) [60.5 mu M] methacetin in the presence of the same concentrations of other pesticides such as benzanilide, propanil, tribenuron methyl, rimsulfuron, metsulfuron methyl and chlorsulphuron ranged from 89.2% to 98.3%. The oxidation peak of 10 mg L-1 [65.3 mu M] dopamine appeared at +0.740 V(vs. Ag/AgCl) and did not display a significant interfering effect, therefore methacetin and dopamine could be simultaneously determined.
Citation Count: 15
Square Wave Voltammetric Determination of Fomesafen Herbicide Using Modified Nanostructure Carbon Paste Electrode as a Sensor and Application to Food Samples
(Springer, 2017) Demir, Ersin; Inam, Recai
Cyclic and square wave voltammetric measurements were performed to deduce the electrochemical behavior of fomesafen herbicide on the prepared carbon nanotube paste electrodes. Fomesafen has created a well-defined cathodic peak at -540 mV (vs. Ag/AgCl), but no corresponding oxidation peak has appeared on the reverse scan. The influence of the pH on the electro-reduction peak was tested at various pH values, and the E (p) versus pH plot suggested that protons are involved in reduction process. Electrochemical studies showed that -NO2 group was responsible for the reduction process. A linear relationship has been constructed in the concentration range of 0.30-40 mg/L. The limits of detection and quantification values were obtained as 0.089 and 0.297 mg/L, respectively. Fomesafen was determined in the presence of some well-known pesticides, and the extent of recoveries of 5 mg/L fomesafen in the presence of equal amounts of pesticides anilazine, pymetrozine, and triflumizole was 103.7 +/- 0.9, 94.3 +/- 0.4, and 97.9 +/- 0.5 %, respectively (n = 3). The accuracy of the recommended method was further proved by the determination of fomesafen in spiked real samples such as apricot juice, cherry juice, and lake water with a relative error of -4.2, -2.8, and -1.8 %, respectively. The obtained results suggest that the recommended method is sufficiently accurate, selective, and precise.
Citation Count: 3
Voltammetric behavior of bupirimate fungicide and its square wave voltammetric determination
(Springer Heidelberg, 2016) Demir, Ersin; Inam, Recai
The voltammeric behavior of bupirimate fungicide has been studied by square wave stripping voltammetry (SWSV). The insoluble R-HgS salt (where R is the bupirimate frame excluding sulfur) formed on the static hanging mercury drop electrode (SHMDE) was electrochemically reduced by giving a fairly well defined cathodic peak within the pH range of 1.0 to 8.0. The peak potentials (E (p)) were shifted toward more negative values with increasing pH, and a maximum peak response appeared at -1320 mV (vs. Ag/AgCl) at a pH 6.0. The calibration plot was a straight line in the range of 0.013 to 9.43 mg L-1. The detection limit at pH 6.0 was measured as 4.0 mu g L-1 under the conditions of E (acc) = -700 mV and t (acc) = 10 s. The validity of the recommended method was assessed from the recoveries of spiked tap water, natural peach juice, and commercial peach juice.
Citation Count: 16
Voltammetric Determination of Ophthalmic Drug Dexamethasone Using Poly-glycine Multi Walled Carbon Nanotubes Modified Paste Electrode
(Bentham Science Publ Ltd, 2018) Demir, Ersin; Inam, Onur; Inam, Recai; Aboul-Enein, Hassan Y.
Background: Dexamethasone has been used in ophthalmology for the treatment of different eye diseases and it is a powerful synthetic member of the glucocorticoid class of steroid medicament having anti-inflammatory and immunosuppressant characteristics. The aim of this study is to develop a rapid, sensitive and selective voltammetric method for its determination using polygylcine-multi walled carbon nanotubes (polyglycine-MWCNTs) modified paste electrode. Methods: The electro-activity and the voltammetric behavior of dexamethasone on the polyglycine-MWCNTs electrode were deduced by cyclic voltammetry (CV), square wave stripping voltammetry (SWSV), differential pulse voltammetry (DPV) and linear sweep voltammetry (LSV). The method permits accurate and sensitive detection of the ophthalmic drug dexamethasone in the presence of ascorbic acid, dopamine and uric acid from the generated anodic peaks at +950 mV, +740 mV and +700 mV, respectively. Results: The cyclic voltammetric study indicates that dexamethasone created a single anodic peak at about +1100 mV in pH 3 B-R solution and none of the cathodic peak appeared in the subsequent reverse scan. The detection and quantification limits measured for LSV were 0.087 mg/L and 0.29 mg/L, respectively. The extent of recoveries in the presence of equal amounts (1: 1 mass ratio) of ascorbic acid, dopamine and uric acid were calculated as 98.28 +/- 0.45, 94.46 +/- 1.77 and 98.57 +/- 0.60%, respectively. The voltammetric procedure was also applied to dexamethasone spiked urine samples(5.0 mg/L) and the percent recovery was determined as 95.2% with the relative standard deviations of 3.29%. Conclusion: Sensitive and selective voltammetric method was proposed for the direct determination of dexamethasone. The modified polyglycine-MWCNTs paste electrode enabled the direct determination of dexamethasone in the presence of biological molecules such as ascorbic acid, dopamine and uric acid.
Citation Count: 3
Voltammetric determination of phenmedipham herbicide using a multiwalled carbon nanotube paste electrode
(Tubitak Scientific & Technological Research Council Turkey, 2018) Demir, Ersin; Inam, Recai
Phenmedipham is an herbicide used especially in the sugar beet harvest to fight against broad-leaved weeds and studies of its voltammetric behavior and detection have not been done before. The superior properties of carbon nanotubes such as electrical conductivity, mechanical strength, and wide potential ranges make them attractive for chemical sensors and the phenmedipham compound gave an oxidation peak at +1320 mV (vs. Ag/AgCl) on the nanostructured multiwalled carbon nanotube paste electrode. Square wave voltammetric measurements recorded for phenmedipham showed that the peak current increased linearly between 0.02 and 2.0 mg/L with a regression coefficient of r = 0.9989, and the limit of detection and limit of quantification were calculated as 6.96 mu g/L and 23.2 mu g/L, respectively. The applicability and the selectivity of the improved square wave voltammetric method for the phenmedipham assay were investigated in the presence of certain herbicides and fungicides such as carbendazim, benomyl, aclonifen, ethofumesate, metamitron, and p-acetamsidide (methacetin) Phenmedipham at 1 mg/L with the same amount of these pesticides was determined to have recoveries of 103.5 +/- 0.07, 94.5 +/- 2.8, 104.3 +/- 1.8, 101.9 +/- 3.1, 93.8 +/- 1.7, and 101.3 +/- 1.8, respectively (n = 3). The method was also applied to the phenmedipham assay in saturated tea sugar prepared as a spiked natural sample and 1.0 g/L phenmedipham in the sugar solution was successfully determined with a relative error of -5.0% and a relative standard deviation of 3.16%.
Citation Count: 6
VOLTAMMETRIC DETERMINATION OF VARDENAFIL ON MODIFIED ELECTRODES CONSTRUCTED BY GRAPHITE, METAL OXIDES AND FUNCTIONALIZED MULTI-WALLED CARBON NANOTUBES
(Editura Acad Romane, 2019) Demir, Ersin; Bozal-Palabiyik, Burcin; Uslu, Bengi; Inam, Recai
The voltammetric behavior of the vardenafil was investigated by means of square wave stripping voltammetry (SWSV), differential pulse stripping voltammetry (DPSV) and cyclic voltammetry (CV) on the modified electrodes constructed by graphite, metal oxide and functionalized multi-walled carbon nanotubes (MWCNT).Different experimental conditions were optimized such as pH and electrolyte type, accumulation potential and accumulation time for both techniques and step potential, pulse amplitude and frequency for SWSV. In the optimum conditions a linear relationship has been constructed in the concentration range of 0.02 to 1.0 mg/L and 0.01 to 0.5 mg/L for SWSV and DPSV in pH 3.0 phosphate buffer solution, respectively. Limit of detection (LOD) values for vardenafil determinations were13.6 mu g/L and 4.38 mu g/L for SWSV and DPSV, respectively. Quantifications were performed on commercial pharmaceutical tablets and synthetic blood serum using both techniques. The relative errors were +5.0% and -3.0% for SWSV and DPSV, respectively in the determination of vardenafil active ingredient in Levitra (R) tablet. SWS and DPS voltammetric determination of synthetic blood serum spiked with 50.0 mu g/L vardenafil exhibited 100.8% and 104.4% recovery, respectively. Interference effects of some organic species such as ascorbic acid, uric acid, dopamine, glucose have also been investigated.