Browsing by Author "Pinar, Pinar Talay"

Now showing 1 - 20 of 28

Adsorptive Stripping Voltammetric Determination of Higenamine on a Boron-Doped Diamond Electrode Improved by the Use of an Anionic Surfactant
(Elsevier Science Sa, 2020) Allahverdiyeva, Shabnam; Pinar, Pinar Talay; Keskin, Ertugrul; Yunusoglu, Oruc; Yardim, Yavuz; Senturk, Zuhre
The present work describes the first electroanalytical investigation and a new voltammetric method for a cheap, rapid and simple determination of higenamine at a surface of mildly-oxidized boron-doped diamond electrode (at +1.6 V during 180 s). The oxidation of compound was strongly dependent on pH. The sensitivity of method was significantly improved in the presence of anionic surfactant, sodium dodecyl sulfate (SDS). The first oxidation peak was chosen for the electroanalytical determination of higenamine due to its higher sensitivity compared to the other two ones. By employing square-wave stripping mode, there was a linear dependence of the oxidation peak current at +0.75 V and higenamine concentration in the range of 0.5-30.0 mg L-1 (1.84 x 10(-6)-1.11 x 10(-4) M), with a detection limit of 0.13 mg L-1 (4.79 x 10(-7) M) in BR buffer pH 2.0 containing 2 x 10(-4) M SDS (after 30 s accumulation at open-circuit condition). As an example, the practical applicability of the proposed method was tested with the quantification of higenamine in the commercial dietary supplement formulations, with results in good agreement to those obtained declared by high-performance liquid chromatography with diode-array detection as a reference method.
Analytical Determination of the Oxazolidinone Antibiotic Linezolid at a Pencil Graphite and Carbon Paste Electrodes
(Wiley-v C H verlag Gmbh, 2019) Aydin, Ilknur; Akgun, Hilal; Pinar, Pinar Talay
Electrochemical properties of linezolid, an antibiotic drug, using unmodified renewable pencil graphite and carbon paste electrodes, were investigated from pH 2 to 10 in Britton-Robinson buffer solution. Experimental studies were examined by square-wave (SW) and cyclic voltammetry (CV). Firstly, parameters affecting the performance of both electrode, such as electrode activation, support electrolyte selection, pH effect, interval of potentials, scan rates and voltammetric method parameters were investigated in detail by using square wave voltammetry. Linezolid was not reversibly oxidized in supporting electrolytes solutions, yielding well-defined peaks in the oxidation potential interval. Using the pencil graphite electrode (PGE), a linearity range between peak current and concentration was obtained between 0.01 and 0.2 mu g mL(-1) (2.96x10(-8)-5.93x10(-7) M), other one, at carbon paste electrode (CPE), a linearity range between 0.1 and 7.5 mu g mL(-1) (2.96x10(-7)-2.22x10(-5) M) was obtained by SWV. The selectivity, sensitivity, precision, and other validation parameters of the developed voltammetric method was evaluated. Lastly, the concentration of linezolid was examined in pharmaceutical and biological samples with standard addition technique.
Development of a Novel Electrochemical Method for the Quantitative Analysis of Vandetanib in the Presence of Anionic Surfactant Utilizing a Bare Carbon Paste Electrode
(Marmara Univ, 2024) Pinar, Pinar Talay; Mete, Cihat; Senturk, Zuhre
In this investigation, a novel electrochemical approach employing a bare carbon paste electrode (CPE) has been devised for the sensitive and expeditious quantification of the tyrosine kinase inhibitor vandetanib (VAN). VAN, a pivotal anti-tumor agent employed in various cancer types, notably medullary thyroid cancer, manifested an irreversible oxidation peak at approximately +1.17 V (vs. Ag/AgCl, 3 M NaCl) in 0.1 M HNO3, 3 , elucidated through cyclic voltammetry. The electrode reaction was determined to proceed via controlled adsorption. The study meticulously examined the influence of anionic surfactant sodium dodecyl sulfate (SDS), instrumental parameters, pH fluctuations, and the composition of the supporting electrolyte on the oxidation peak of VAN. Remarkably, the sensitivity of stripping voltammetric measurements markedly augmented upon the inclusion of 9 x 10-4 - 4 M SDS. Employing optimized parameters for SW-AdSV (square-wave adsorptive stripping voltammetry), the bare CPE demonstrated exceptional linearity within the dynamic ranges of 1.05x10-7 - 7 - 1.6x10-5 - 5 M for VAN. The limit of detection and limit of quantification were established at 2.7x10-8 - 8 and 9.0x10-8 - 8 M for VAN, respectively. Furthermore, the developed electrochemical methodology was effectively applied for the detection of VAN in spiked model serum samples.
Electroanalytical Investigation and Determination of Hepatitis C Antiviral Drug Ledipasvir at a Non-Modified Boron-Doped Diamond Electrode
(Elsevier Science Sa, 2020) Allahverdiyeva, Shabnam; Keskin, Ertugrul; Pinar, Pinar Talay; Yunusoglu, Oruc; Yardim, Yavuz; Senturk, Zuhre
This study is about the use of the boron-doped diamond electrode pretreated electrochemically (anodic and subsequent cathodic) in the voltammetric determination of hepatitis C antiviral drug ledipasvir. Cyclic voltammetric measurements revealed that the compound yielded two well-separated irreversible oxidation peaks (P-A1 and P-A2) in acidic medium. The dependence of intensities of currents and potentials on electrode pretreatment, pH and nature of the supporting electrolyte, and other variables was investigated by square-wave voltammetry. Determination of ledipasvir was performed in Britton-Robinson buffer (pH 2.0) on the basis of both P-A1 and P-A2, which offered linear concentration ranges 0.5-60.0 mu g mL(-1) (5.6 x 10(-7)-6.8 x 10(-5) mol L-1) and 5.0-60.0 mu g mL(-1) (5.6 x 10(-6)-6.8 x 10(-5) mol L-1), respectively, with detection limits of 0.12 mu g mL(-1) (1.4 x 10(-7) mol L-1) and 0.76 mu g mL(-1) (8.6 x 10(-7) mol L-1). The practical applicability of developed methodology was tested by the assay of a fixed-dose combination tablet with sofosbuvir.
Electrochemical and Analytical Performance of Cathodically Pretreated Boron-Doped Diamond Electrode for the Determination of Oxazolidinone Antibiotic Linezolid in Cationic Surfactant Media
(Elsevier Science Sa, 2020) Pinar, Pinar Talay; Senturk, Zuhre
The electrochemical oxidation of an oxazolidinone class of antibiotic, Linezolid (LNZ) was studied in aqueous as well as aqueous/surfactant media on a commercially available boron-doped diamond (BDD) electrode pretreated cathodically. By using cyclic voltammetry, LNZ showed two couples of oxidation/reduction peak in aqueous solutions. The electrode process is pH-dependent and controlled by diffusion. The compound yielded two well-separated oxidation steps in acidic, neutral and alkaline media by employing square-wave voltammetry. The sensitivity of the voltammetric measurements was improved when the cationic surfactant, cetyltrimethylammonium bromide (CTAB) was present in the electrolyte solution at pH 4.0. In Britton-Robinson buffer containing 0.9 mM CTAB, the calibration curves were linear for both oxidation peaks (Ia and IIa) over concentration ranges of 0.25-6.41 mu g mL(-1) (0.74-19.27 mu M), with detection limits of 0.05 mu g mL(-1) (0.15 mu M) for Ia, and 0.12 mu g mL(-1) (0.34 mu M) for IIa. The practical applicability of developed methodology was tested in pharmaceutical formulations.
Electrochemical Behavior of Janus Kinase Inhibitor Ruxolitinib at a Taurine-Electropolymerized Carbon Paste Electrode: Insights Into Sensing Mechanisms
(Amer Chemical Soc, 2024) Subak, Hasret; Pinar, Pinar Talay
Ruxolitinib (RXL) is a Janus kinase inhibitor used for treating intermediate- or high-risk myelofibrosis. This study presents an electrode modified with electrochemically polymerized taurine on a carbon paste electrode via cyclic voltammetry (CV). The surface characterization of the poly(taurine)-CP electrode was evaluated by using electrochemical (electrochemical impedance spectroscopy-EIS, CV), morphological (scanning electron microscope-SEM), and spectroscopic (Fourier-transform infrared spectroscopy-FT-IR) techniques. Under optimized conditions, RXL exhibited good linearity within the 0.01-1.0 mu M concentration range, with a limit of detection (LOD) of 0.005 mu M. The proposed electrochemical sensor demonstrated excellent selectivity, accuracy, precision, and repeatability. Furthermore, it effectively detected RXL in human urine and pharmaceutical samples.
Electrochemical Determination of Anti-Cancer Drug Dabrafenib With High Sensitivity Using Multi-Walled Carbon Nano Tubes Modified Glassy Carbon Electrode
(Wiley-v C H verlag Gmbh, 2024) Mete, Cihat; Pinar, Pinar Talay
Dabrafenib (DAB) is an organofluor compound and a protein kinase inhibitor used as the mesylate salt in the treatment of metastatic melanoma. For the first time, the electrochemical investigation of the anticancer drug DAB in human serum was conducted using a glassy carbon electrode modified with multi-walled carbon nanotubes (MWCNTs), employing cyclic voltammetry and square wave voltammetry (SWV) techniques. Electrochemical impedance spectroscopy, cyclic voltammetry, and scanning electron microscopy (SEM) techniques were utilized to analyze the surface morphology and structure of the MWCNT/GC electrode. In the proposed method using optimized experimental conditions, two different linearities were obtained for DAB in the concentration range of 0.04-0.8 mu M and 1.0-10.0 mu M. The LOD value obtained is 0.014 mu M. In this study, the resulting electrochemical sensor was applied for the first time to investigate the electrochemical behavior of DAB with high sensitivity and reproducibility, as well as the possible electrochemical oxidation mechanism. Dabrafenib, a organofluor compound and a protein kinase inhibitor, was electrochemically analyzed for the first time on a MWCNT-modified GCE, proposing an oxidation mechanism. Surface morphology and structure were examined using electrochemical impedance spectroscopy, cyclic voltammetry, and scanning electron microscopy. The electrode reaction was irreversible and diffusion-controlled, accompanied by a -2e-/2H+ oxidation reaction. Under optimized experimental conditions, two different linear ranges were obtained for DAB in 0.2 M H2SO4 solution, ranging from 0.04 to 0.8 mu M and 1.0 to 10.0 mu M, with a LOD value of 0.014 mu M. This developed method was applied to biological samples. image
Electrochemical Determination of Fluoroquinolone Antibiotic Norfloxacin in the Presence of Anionic Surfactant Using the Anodically Pretreated Boron-Doped Diamond Electrode
(Wiley-v C H verlag Gmbh, 2020) Karahan, Fatih; Basi, Zehra; Keskin, Ertugrul; Pinar, Pinar Talay; Yardim, Yavuz; Senturk, Zuhre
In this article, a simple, fast and inexpensive methodology has been developed for the determination of fluoroquinolone class antibiotic norfloxacin (NFX) in anionic surfactant media (sodium dodecyl sulphate, SDS) using an anodically pretreated boron-doped diamond (APT-BDD) electrode. Cyclic voltammetric studies showed that the NFX gave an irreversible and adsorption controlled anodic oxidation signal at a potential of about +1.32 V on the APT-BDD electrode. The effects of parameters such as the electrode pre-treatment procedure, SDS concentration, and instrumental variables on the electrochemical sensitivity of NFX were evaluated. Under optimized conditions, the linearity was achieved in the range of 0.05 to 4.0 mu g mL(-1) (1.57x10(-7)-1.25x10(-5) mol L-1), with a detection limit of 0.013 mu g mL(-1) (4.07x10(-8) mol L-1) by using square-wave adsorptive stripping voltammetry (SW-AdSV). The feasibility of the developed approach for the quantification of NFX in urine samples was tested.
Electrooxidation and Low-Tech Determination of Pantoprazole on a Disposable Pencil Graphite Electrode by the Use of Cationic Surfactant
(Slovensko Kemijsko Drustvo, 2020) Pinar, Pinar Talay
The electrochemical oxidation of pantoprazole, a selective proton pump inhibitor, was studied in aqueous as well as aqueous/surfactant media at a disposable pencil graphite electrode using cyclic and adsorptive stripping voltammetric techniques. The sensitivity of the stripping voltammetric measurements was significantly improved when the cationic surfactant, cetyltrimethylammonium bromide (CTAB) was present in the neutral electrolyte solution. For analytical purposes, well resolved voltammetric peaks at +1.05 V (versus Ag/AgCl) were obtained in Britton-Robinson buffer at pH 7.0 containing 3 x 10(-4) M CTAB using square-wave stripping mode (after 30 s accumulation at open-circuit condition). The process could be used to determine pantoprazole concentrations in the range of 2.4 x 10(-8) -7.1 x 10(-7) M (9.2-272 mu g L-1) with a detection limit of 7.0 x 10 -9 M (2.7 mu g L-1). The proposed method was applied to the determination of pantoprazole in pharmaceutical formulation and in the spiked human urine samples with acceptable recoveries.
The First Approach for the Simultaneous Quantification of Isoproturon, Carbendazim, and Carbofuran at the Surface of a Mil-101(cr) Metal-Organic Framework-Based Electrode
(Elsevier, 2023) Pinar, Pinar Talay; Yardim, Yavuz; Gulcan, Mehmet; Senturk, Zuhre
A novel approach has been proposed for the simultaneous detection of isoproturon (ISO), carbendazim (CAR), and carbofuran (CRF) pesticides. This is achieved by employing an electrochemical sensor modified with nano- MIL-101(Cr) on a glassy carbon electrode, providing high selectivity and sensitivity. Structural and morpho-logical analysis of the nanomaterial was conducted using SEM, SEM/EDX, SEM Elemental Mapping, P-XRD, and FT-IR techniques. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and square wave voltammetry (SWV) techniques were utilized to characterize nano-MIL-101(Cr) and assess its suitability as an electrode material for sensing purposes. The electrochemical sensor demonstrated strong linearity in simultaneously determining ISO (+0.98 V, vs. Ag/AgCl), CAR (+1.19 V, vs. Ag/AgCl), and CRF (+1.34 V, vs. Ag/AgCl) across concentration ranges of 0.25-2.50 mu M, 0.1-2.0 mu M, and 1.0-20.0 mu M, respectively, under optimized conditions. Detection limits for ISO, CAR, and CRF were determined as 0.015 mu M, 0.02 mu M, and 0.32 mu M, respectively. The proposed electrochemical sensor was effectively employed for analyzing real samples, such as soil and river water, for pesticide detection.
First Electroanalytical Methodology for the Determination of Hordenine in Dietary Supplements Using a Boron-Doped Diamond Electrode
(Wiley-v C H verlag Gmbh, 2019) Allahverdiyeva, Shabnam; Keskin, Ertugrul; Pinar, Pinar Talay; Yardim, Yavuz; Senturk, Zuhre
The present work describes the first electrochemical investigation and a simple, rapid and modification-free electroanalytical methodology for quantification of hordenine (a potent phenylethylamine alkaloid) using a boron-doped diamond electrode. At optimized square-wave voltammetric parameters, the observed oxidation peak current in 0.1 M HClO4 at +1.33 V (vs. Ag/AgCl) increased linearly from 5.0 to 100 mu g mL(-1) (3.0x10(-5)-6.1x10(-4) M), with detection limit of 1.3 mu g mL(-1) (7.8x10(-6) M). The applicability of the developed method was tested with the determination of hordenine in the commercial dietary supplement formulations.
First Report for the Electrochemical Determination and Proposed Mechanism of Poly(Adp Ribose) Polymerase Inhibitor and New Smart Anticancer Drug Olaparib
(Springer Wien, 2023) Goktas, Dicle; Pinar, Pinar Talay
A sensitive, rapid, and inexpensive electrochemical method with an unmodified carbon paste electrode (CPE) was developed for the first time for voltammetric determination of poly(ADP-Ribose) polymerase (PARP) inhibitor olaparib (OLA) used in the treatment of advanced ovarian cancer, metastatic breast, and prostate cancer. OLA showed an irreversible oxidation peak at physiological pH (pH 7.4) at approximately + 1.31 V by the cyclic voltammetry technique. Using the suitable values of square-wave voltammetric parameters, the CPE showed good linearity in the concentration ranges of 5.8 x 10(-7)-4.6 x 10(-5) mol dm(-3) for OLA. The limit of detection and limit of quantification were determined to be 2.9 x 10(-8) and 9.7 x 10(-8) mol dm(-3) for OLA, respectively. Besides its high stability and reproducibility, the response of OLA at CPE was not affected in the presence of dopamine, uric acid, and ascorbic acid. The developed electrochemical method has been successfully applied for the detection of OLA in the spiked human urine sample.{GRAPHICAL ABSTRACT}
First Report for the Electrochemical Investigation of a New Hiv Integrase Inhibitor Dolutegravir: Its Voltammetric Determination in Tablet Dosage Forms and Human Urine Using a Boron-Doped Diamond Electrode
(Elsevier Science Sa, 2021) Allahverdiyeva, Shabnam; Pinar, Pinar Talay; Yardim, Yavuz; Senturk, Zuhre
In this paper, for the first time, the study of electrochemical investigation and voltammetric determination of HIV integrase inhibitor dolutegravir was described. The effect of pretreatment (anodically or cathodically) of borondoped diamond electrode was investigated in detail on the stripping voltammetric performance for this compound. Dolutegravir presented one or two oxidation peaks within the pH range 2.0-12.0 by using both pretreated electrodes. Employing square-wave stripping mode on the surface of cathodically pretreated boron-doped diamond electrode (after 60 s accumulation at +0.3 V) in Britton-Robinson buffer at pH 10.0, there was a linear dependence of the peak current at +0.79 V (vs. Ag/AgCl, 3 M NaCl) and dolutegravir concentration in the range of 1.0-50.0 mu g mL(-1) (2.38 x 10(-6) -1.19 x 10(-4) M), with a detection limit of 0.26 mu g mL(-1) (6.20 x 10(-7) M). The applicability of the developed approach for the quantification of dolutegravir was tested in the commercial tablet formulations and model human urine samples.
Highly Selective Electrochemical Sensor for New Generation Targeted-Anticancer Drug Ibrutinib Using Newly Synthesized Nanomaterial Go-Nh Modified Glassy Carbon Electrode
(Elsevier Sci Ltd, 2023) Amudi, Karina; Yigit, Aybek; Menges, Nurettin; Pinar, Pinar Talay
Ibrutinib (IBR) is a small molecule new generation smart anti-cancer drug that is Bruton's tyrosine kinase (BTK) inhibitor. In this study, the sensitive and selective electrochemical sensor based on a modification of a glassy carbon electrode with a new GO-NH-B(OH)2 (graphene oxide boramidic acid) nanoparticles and Ag nano -particles (AgNPs) is proposed for IBR determination. GO-NH-B(OH)2@AgNPs/GCE was characterized by scan-ning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The performance of the electrode was evaluated with the parameters of electrode surface area (A), heterogeneous rate constant (ket), standard exchange current density (I0). The electrochemical determination of IBR in 0.1 M HNO3 solution was investigated at the surface of GO-NH-B(OH)2@AgNPs/GCE. Under optimized square wave voltammetric (SWV) conditions, peaks current at GO-NH-B(OH)2@AgNPs/GCE showed good linearity with the concentration of IBR in the operating range of 0.025-1.00 mu g mL-1 (5.7 x 10-8 - 2.3 x 10-6 M) with a detection limit (LOD) of 0.006 mu g mL-1 (1.36 x 10-8 M). Besides its high stability and reproducibility, the response of IBR at GO-NH-B (OH)2@AgNPs/GCE was not influenced by the presence of dopamine, uric acid, and ascorbic acid. The sensor has successfully caught IBR in pharmaceutical and human urine samples.
Individual and Simultaneous Electroanalytical Sensing of Epinephrine and Lidocaine Using an Anodically Pretreated Boron-Doped Diamond Electrode by Square-Wave Voltammetry
(Elsevier Science Sa, 2020) Pinar, Pinar Talay; Yardim, Yavuz; Senturk, Zuhre
In this study, the individual and simultaneous determination of lidocaine (LID) and epinephrine (EP) were examined using an anodically pretreated boron-doped diamond (APT-BDD) electrode. The results of cyclic voltammograms of the binary mixtures of EP and LID were manifested by two irreversible and diffusion-controlled peaks at about +0.91 V (for EP) and +1.67 V (for LID) in Britton-Robinson buffer at pH 2.0. The dependence of oxidation peak potential and current on experimental and instrumental parameters was also investigated at the surface of the APT-BDD electrode. Under the optimal conditions, employing square-wave voltammetric mode, the APT-BDD electrode was used for determination of LID and EP simultaneously in the ranges of 0.1-20.0 mu mol L-1 and 1.0-100.0 mu mol L-1, with detection limits of 0.03 mu mol L-1 and 0.27 mu mol L-1, respectively. The proposed approach could be used for their determination individually and selectively (in the case of EP) in pharmaceutical dosage forms with acceptable recoveries.
Nanomolar Detection and Electrochemical Mechanism of Nintedanib Via Square-Wave Voltammetry Using a Mwcnt-Modified Glassy Carbon Electrode
(Elsevier Science Sa, 2025) Subak, Hasret; Bas, Halime; Pinar, Pinar Talay
This study focuses on the electrochemical analysis of Nintedanib (NTD), a therapeutic agent used to treat idiopathic pulmonary fibrosis (IPF), employing a glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes (MWCNT). The electrochemical modified electrode was comprehensively characterized using techniques such as electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and field emission scanning electron microscopy (FE-SEM). Afterward, the MWCNT-modified GCE was optimized to enhance its performance for detecting NTD. For the first time, an electrochemical oxidation mechanism of NTD was suggested using this sensor. The optimized sensor showed excellent linearity within the concentration range of 0.01 to 0.40 mu M and achieved a detection limit as low as 0.0037 mu M. Moreover, the sensor proved to be effective in analyzing NTD in biological samples. These results underline the strong potential of the MWCNTmodified GCE as a highly sensitive platform for NTD electrochemical analysis.
Nanotube-Boramidic Acid Derivative for Dopamine Sensing
(Wiley-v C H verlag Gmbh, 2021) Yigit, Aybek; Pinar, Pinar Talay; Akinay, Yuksel; Alma, Mehmet Hakki; Menges, Nurettin
A new sensor, based on boramidic acid-bounded MWCNTs (Multi-walled carbon nanotubes), was synthesized in three simple steps. Modification of the sensor surface was accomplished using boric acid in which the boron atom is adjacent to the NH group. Characterization, electrochemical behaviors, and stability of newly modified nanosensor were completed using SEM (scanning electron microscope), TEM (Transmission electron microscope), CV (cyclic voltammetry), EIS (electron impedance), DTA (Differential thermal analysis), and XPS (X-ray photoelectron spectroscopy). SEM and TEM analysis were confirmed the modified surface of the nanosensor. The stability of the newly synthesized sensor was also designated that the initial weight loss occurred between 50-145 degrees C was corresponded to the degradation of both ethylene diamine and boric acid. According to the EIS study, the Nyquist plot of the MWCNTs-NH-B (OH)(2)/GC electrode displayed a 0.435 k omega Rct with a smaller semicircle than the bare GC (6.57 k omega). The electrochemical behavior of dopamine was investigated using cyclic and square wave voltammetry (0.1 M phosphate buffer solution-pH 7.4). The diffusion-controlled process was determined when the oxidation of dopamine was studied. The detection limit of dopamine was found to be 5.1 nM. An actual sample study was done using the developed analytical method, and the detection of dopamine in urine was successfully performed. This study is the first example of boramidic acid-modified multi-walled carbon nanotubes
Quantification of Ferulic Acid Using Square-Wave Voltammetric Method at an Unmodified Boron-Doped Diamond Electrode
(Springer Wien, 2023) Pinar, Pinar Talay; Barzani, Hemn A. H.; Ali, Hoshyar Saadi; Yardim, Yavuz
For the first time, a boron-doped diamond electrode was employed in square-wave voltammetry for the sensitive and selective measurement of ferulic acid (FA). The impact of the electrode's pretreatment procedure on the current response was investigated, leading to the discovery that the consecutive pretreatment approach yielded the most optimal signal results. This determination was made upon observing that the highest quality signal could be obtained through this method. The electrochemical oxidation of FA was studied in aqueous media on a cathodically pretreated boron-doped diamond electrode. FA was shown to have two sets of oxidation/reduction peaks when tested in aqueous solutions using cyclic voltammetry. Diffusion governs the electrode process, which is pH-dependent. In 0.1 mol dm-3 H2SO4, the calibration curves were linear for FA peak over dynamic ranges of 5.1 x 10-7-4.1 x 10-5 mol dm-3, via a detection limit of 1.5 x 10-7 mol dm-3. The practical applicability of the developed methodology was tested in the commercial ampoule formulation of FA. The method can be used instead of other analytical methods because it is fast, easy to use, and cheap, has a wide calibration range, and gives consistent results.
Simple and Sensitive Electrochemical Determination of Higenamine in Dietary Supplements Using a Disposable Pencil Graphite Electrode
(Springer Wien, 2020) Pinar, Pinar Talay; Yardim, Yavuz; Senturk, Zuhre
In this study, a cheap, rapid, simple, and modification-free electroanalytical methodology based on the disposable pencil graphite electrode is described for the quantification of higenamine (isoquinoline-type alkaloid having three phenolic OHs). At first, the electrochemical oxidation of higenamine was investigated in aqueous solutions by cyclic voltammetry. The electrode process is pH-dependent and controlled by a mixture of diffusion and adsorption processes. Higenamine yielded two well-separated oxidation steps in acidic, neutral, and alkaline media by using square-wave voltammetry. By using the first oxidation peak due to its higher sensitivity, there was an excellent correlation between oxidation peak current at + 0.44 V and higenamine concentration (as hydrochloride salt) in the range of 0.05 to 2.0 mu g cm(-3) (1.63 x 10(-7)-6.5 x 10(-6) mol dm(-3)), with a detection limit of 0.014 mu g cm(-3) (4.55 x 10(-8) mol dm(-3)) in Britton-Robinson buffer at pH 4.0. As an example, the developed approach can be used for the quantification of higenamine in the commercial dietary supplement formulations. Graphic abstract
Simultaneous Voltammetric Determination of Vanillin and Caffeine in Food Products Using an Anodically Pretreated Boron-Doped Diamond Electrode: Its Comparison With Hplc-Dad
(Elsevier Science Bv, 2017) Ali, Hoshyar Saadi; Abdullah, Abdullah A.; Pinar, Pinar Talay; Yardim, Yavuz; Senturk, Zuhre
This paper describes an electroanalytical method for the simultaneous determination of vanillin (VAN) and caffeine (CAF) using an anodically pretreated boron-doped diamond electrode. Selective determination of one compound in the presence of other one was also realized. Both compounds yielded a single irreversible oxidation peak using cyclic voltammetry. The nature of the electrode reaction was found to be diffusion controlled with contribution of adsorption. By using square-wave adsorptive stripping voltammetry after 60 s accumulation under open-circuit voltage, method allowed simultaneous determination of VAN and CAF in phosphate buffer, pH 2.5, with detection limits of 0.234 g (1.54x10(-6) M) and 0.071 mu g mL(-1) (3.66x10(-7)M), respectively. The proposed method was successfully applied in the selective and simultaneous determination of VAN and CAF in commercial food and beverage samples. In addition, for the comparison, high-performance liquid chromatographic method with diode-array detection was developed for the first time for their simultaneous determination.