9 sonuçlar
Arama Sonuçları
Listeleniyor 1 - 9 / 9
Öğe New voltammetric strategy for determination and electrochemical behaviors of metformin by pencil graphite electrode in the NaOH(Indian Chemical Society, 2020) Altunkaynak, Yalçın; Yavuz, Ömer; Levent, AbdulkadirMetformin(MET), an oral antidiabetic drug commonly used in the treatment of diabetes, is a drug that increases insulin sensitivity in the biguanide group [1]. MET shows its pharmacological effect by lowering the glucose level in the blood. In the literature research, there are studies using electrochemical techniques for the analysis of MET in biological fluid and drug forms[1-6]. In this study, the electrochemical properties of MET, one of the drugs used in the treatment of diabetes, were performed using a pencil graphite electrode in NaOH (0.1 M) solution. This compound was recorded with an irreversible and diffusion controlled adsorption oxidation peak at approximately +1.28 V by cyclic voltammetry. With square wave stripping voltammetry, it was observed that the peak current signals of MET in the concentration range of 2.76-24.8 µM in 0.1M NaOH solution increased linearly. At a concentration of 2.76 µM (n = 9), the limit of detection and relative standard deviation were calculated as 9.03 nM (1.495 ngmL-1 ) and 3.25 %, respectively. This method has been successfully applied for MET analysis in pharmaceutical preparations and urine samples without any separation.Öğe Voltammetric behavior of acebutolol on pencil graphite electrode: highly sensitive determination in real samples by square‑wave anodic stripping voltammetry(Iranian Chemical Society, 2017-08-22) Levent, AbdulkadirIn this work, an electrochemical investigation of acebutolol (ACE), a beta-blocker drug, was carried out in alkaline medium using pencil graphite (PG) electrode. In cyclic voltammetry, the compound displayed a reversible and adsorption-controlled oxidation peak. By using squarewave anodic stripping voltammetry, the oxidation peak current observed at +0.78 V showed a linear relationship with concentration at 0.4–7 nM interval in Britton–Robinson bufer (pH 10.0) and a detection limit of 0.09 nM. The relative standard deviation of 4.72% for the concentration level of 2.0 nM (n = 11) was also calculated. The PG electrode that is used for the frst time in this method was successfully applied to determine the ACE in pharmaceutical formulations and urine.Öğe Simultaneous electrochemical evaluation of ascorbic acid, epinephrine and uric acid at disposable pencil graphite electrode: Highly sensitive determination in pharmaceuticals and biological liquids by differential pulse voltammetry(Elsevier, 2018) Levent, Abdulkadir; Önal, GünayAim and Objective: As is known, AA, EP and UA can also coexist in biological fluids. Therefore, the determination of the levels of these compounds in biological fluids is extremely important both for the diagnosis and treatment of the related diseases. In the presence of many interfering substances in biological fluids such as blood and urine samples, it is very important that these compounds can be selectively analyzed. Materials and Methods: All electrochemical experiments were performed using an Autolab PGSTAT 128N potentiostat. Before beginning the electrochemical measurements, the PGE was activated. The electrochemical pretreatment of PG was exercised by anodically +1.40 V for 60 s. Then, measurements were performed with CV (-0.4 V to 1.2 V) and DPV (-0.2 V to 0.7 V) for single and simultaneous voltammetric behaviour of AA, EP, and UA in the electrochemical method. Results: The anodic peak potentials of AA and UA were observed at about +0.32 V and +0.62 V, respectively. On the other hand, for EP, while anodic peak potential was observed at about +0.53 V, in the reverse scan, cathodic peak potentials were observed at about +0.41 V and +0.007 V. The39 reduction peak observed at +0.3 V with the oxidation peak observed at +0.53 V are the reversible peaks. In the method developed for the electrochemical simultaneous determination of AA, EP and UA using PGE with DPV technique in BR buffer solution (pH 4.0), the anodic peak potentials are sufficiently separated from each other. Conclusion: A voltammetric method was developed for the simultaneous determination of AA, EP and UA with PGE for the first time. Here, the most important thing is that the simultaneous determination of AA, EP and UA was successfully achieved with that targeted voltammetric method which was sensitive, low-cost, practical and well-repeated; and that these were proven to be selectively applicable in pharmaceutical products and biological liquids.Öğe New voltammetric strategy for determination and electrochemical behaviors of metformin by pencil graphite electrode(ICNTC, 2020) Altunkaynak, Yalçın; Yavuz, Ömer; Levent, AbdulkadirMetformin(MET), an oral antidiabetic drug commonly used in the treatment of diabetes, is a drug that increases insulin sensitivity in the biguanide group [1]. MET shows its pharmacological effect by lowering the glucose level in the blood. In the literature research, there are studies using electrochemical techniques for the analysis of MET in biological fluid and drug forms[1-6]. In this study, the electrochemical properties of MET, one of the drugs used in the treatment of diabetes, were performed using a pencil graphite electrode in NaOH (0.1 M) solution. This compound was recorded with an irreversible and diffusion controlled adsorption oxidation peak at approximately +1.28 V by cyclic voltammetry. With square wave stripping voltammetry, it was observed that the peak current signals of MET in the concentration range of 2.76-24.8 µM in 0.1M NaOH solution increased linearly. At a concentration of 2.76 µM (n = 9), the limit of detection and relative standard deviation were calculated as 9.03 nM (1.495 ngmL-1 ) and 3.25 %, respectively. This method has been successfully applied for MET analysis in pharmaceutical preparations and urine samples without any separation.Öğe Kalem grafit elektrot kullanılarak edoksaban etken maddesinin elektrokimyasal davranışları ve miktar tayini için voltametrik yöntem uygulaması(Batman Üniversitesi Lisansüstü Eğitim Enstitüsü, 2022-09-13) Kılıç, Abdulkadir; Levent, AbdulkadirBu tez çalışmasında, kan sulandırıcı etki gösteren Edoksaban etken maddesinin BR (pH 9.0) çözelti ortamında kalem grafit elektrot kullanarak kare dalga ve dönüşümlü voltametri teknikleri ile elektrokimyasal özelikleri araştırılmıştır. Edoksaban’nın dönüşümlü voltametri ile alınan ölçümlerinde yaklaşık olarak +0.97 V’ ta iyi tanımlanmış tersinmez bir yanıt vermiştir. Karakterize edilen cihaz parametreleriyle BR (pH 9.0) ortamında 0.2 µM-1.8 µM aralığında doğrusal bir çalışma aralığı sunduğu ve LOD, LOQ sırsıyla değerleri 0.073 μM (0.133 μg mL-1 ) ve 0.243 μM (0.443 μg mL-1 ) olarak saptanmıştır. Tez çalışmasında geliştirilen voltametrik tekniğin uygulama sonuçları UV/Vis tekniği sonuçları ile kıyaslanmış ve birbirlerine göre uyumlu oldukları tespit edilmiştir.Öğe Kurşun kalem elektrot ile podofilotoksin′in elektroanalitik özelliklerinin incelenmesi ve miktar tayini(Batman Üniversitesi Fen Bilimleri Enstitüsü, 2019-11-19) Özer, Mehmet; Levent, AbdulkadirBu tez kapsamında antineoplastik ilaçlar içinde yer alan bitkisel kaynaklı podofilotoksin kanser (meme kanseri, prostat kanseri, kolon kanseri, küçük hücreli akciğer kanseri, lenfomalar, ve genital tümörler) ve siğil tedavilerinde kullanılmaktadır. Podofilotoksin’in miktar tayini için tek kullanımlık olan kalem grafit elektrot (PGE) kullanılarak hassas, duyarlı ve basit bir voltametrik yöntem geliştirilmiştir. Podofilotoksin’in elektrokimyasal özellikleri PG elektrot kullanılarak kare-dalga (SW) ve dönüşümlü voltametri (CV) tekniğiyle incelenmiştir. SW voltametri tekniği kullanılarak Britton Robinson (BR) tamponunda (pH 4.0) içerisinde, podofilotoksin’in +1.242 V (vs. Ag/AgCI) gerilim değerinde (0.0 V’da ve 60 s ön-deriştirme sonrası) çok iyi voltametrik bir yanıt vermiştir. Bu işlem, gözlenebilirlik sınırı 2.55 nM (1.06 µg/L) olan 1.24x10-8 – 29.4x10-8 M (12.4-299.5 nM) derişim aralığında bileşiğin miktar tayini için kullanılmıştır. Önerilen yöntem, insan idrar örneklerinde başarılı bir şekilde uygulanmıştır.Öğe Application of a pencil graphite electrode for voltammetric simultaneous determination of ascorbic acid, norepinephrine, and uric acid in real samples(TÜBİTAK, 2018-04-27) Levent, Abdulkadir; Önal, GünayA pencil graphite electrode (PGE) was used for the simultaneous detection of ascorbic acid (AA), norepinephrine (NE), and uric acid (UA) by differential pulse voltammetry and cyclic voltammetry. The anodic peaks of AA, NE, and UA in their mixture can be well separated in 0.1 M Britton–Robinson buffer solution at pH 4.0. The effects of various experimental parameters such as pH, scan rate, and voltammetric parameters on the voltammetric response of these compounds were investigated. Under optimum conditions, linear calibration graphs were obtained from the AA, NE, and UA concentration ranges, which were 100–800 nM, 20–170 nM, and 40–175 nM, respectively. The detection limits for AA, NE, and UA were 27 nM, 4 nM, and 10 nM in the form of a mixture at the PGE. This electrode shows great analytical performance characteristics, corresponding repeatability and recovery for the simultaneous determination of these compounds. PGE, which was used for the first time in this method, has been successfully applied for the assay of UA in human urine samples with the aim of determining AA and NE in pharmaceutical drugs.Öğe Electrooxidation of thiourea and its square-wave voltammetric determination using pencil graphite electrode(Walter de Gruyter, 2011-04-01) Levent, Abdulkadir; Keskin, Ertuğrul; Yardım, Yavuz; Şentürk, ZühreThe electrochemical properties of thiourea (TU) were investigated in pH range 2.0-12.0 by cyclic and square-wave voltammetry. The compound was irreversibly oxidized at a pencil graphite electrode in one or two oxidation steps which are pH-dependent. Based on the voltammetric peak for the second oxidation process of TU in phosphate buffer at pH 12.0, a square-wave voltammetric method was proposed for the determination of the compound in the range 6.3-30μm, with a detection limit of 1.29μm. The applicability to direct assays of wastewaters was also tested.Öğe Electrochemical oxidation of vildagliptin on pencil graphite electrode: Extremely sensitive determination in drugs and human urine with square wave voltammetry(ICNTC, 2020) Altunkaynak, Yalçın; Yavuz, Ömer; Levent, AbdulkadirVildagliptin (VLDG), one of the antidiabetic agents, is a dipeptidyl peptidase 4 inhibitor. It is a drug developed for oral administration[1]. In the literature, there is only one study in which electrochemical methods were used for the analysis of Vildagliptin in biological fluid and drug forms[2]. In this study, the electrochemical properties of VLDG, which is one of the drugs used as an antidiabetic agent, were determined by using pencil graphite electrode in phosphate buffer solution (PBS/pH 9.0). The irreversible and diffusion controlled adsorption oxidation peak was measured by cyclic voltammetry at approximately +1.13 V for this compound. Using square wave stripping voltammetry, the current showed a linear correlation in PBS buffer at pH 9.0, with a concentration range of 2.94 to 49.98 µM. At a concentration of 2.94 µM (n=9), the limit of detection of 8.20 nM (2.48 ng mL-1 ) and a relative standard deviation of 2.95 % were calculated. This method was successfully applied for VLDG analysis without any separation in pharmaceutical preparations and urine samples
