Browsing by Author "Demir, Ersin"

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Citation Count: 31
Characterization of AlFe-pillared Unye bentonite: A study of the surface acidity and catalytic property
(Elsevier Science Bv, 2015) Caglar, Bulent; Cubuk, Osman; Demir, Ersin; Coldur, Fatih; Catir, Mustafa; Topcu, Cihan; Tabak, Ahmet
Aluminium-iron-pillared bentonite has been prepared by incorporation of the iron mixed aluminium-polyoxocation into bentonite layers and characterized by the powder X-ray diffraction, Fourier transform infrared, thermal analysis and surface area measurement techniques. The characteristic d(001) basal spacing of raw bentonite increased with the pillaring process and reached to 18.05 angstrom. The siloxane layers of bentonite were perturbed and the positions of Si-O stretching vibrations were altered by pillaring process. However, these pillars in the interlayer gallery spacing enhanced the thermal stability of bentonite. The new rnicropores were formed by the pillaring process and the specific surface area of raw bentonite increased by ca. 2-fold for aluminium iron-pillared bentonite. FTIR spectra and thermal analysis curves of pyridine adsorbed samples clearly show that the surface Lewis acidity of aluminium iron-pillared bentonite is greater than that of raw bentonite. Raw and aluminium iron-pillared bentonites have been utilized as solid catalysts for benzoylation of benzene with benzoyl chloride. The aluminium iron-pillared bentonite catalyst showed promising catalytic activity whereas raw bentonite showed no catalytic activity in benzoylation of benzene with benzoyl chloride. (C) 2015 Elsevier B.V. All rights reserved.
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: 0
Developed and characterization of a novel Cd doped CeO₂ nanofilm and application of methyl orange removed by photodegradation
(indian Assoc Cultivation Science, 2024) Söyleyici Çergel, Müge; Demir, Ersin; Kurtaran, Sema; Tıbbi Görüntüleme Teknikleri / Medical Imaging Techniques
Cerium oxide (CeO2) films doped with cadmium (Cd) were synthesized employing the ultrasonic spray pyrolysis technique (USP). The structural, surface, and optical properties of the prepared Cd-doped CeO2 films were also investigated. All films were polycrystalline, exhibiting as cubic fluorite structure. In addition, the optical bandgap obtained using the UV data ranged from 3.23 to 3.52 eV. Cd-doped CeO2 films exhibited Raman scattering, in which the multi-peak setting of the first optical longitudinal mode was observed, indicated the Raman shift of the characteristic peak in the similar to 461 cm(-1) range. In addition, the photodegradation capacities of Cd-doped CeO2 films were investigated for the removal of pesticides that pollute human and environmental health. As a result, proposed Cd-doped CeO2 thin films show very high (approximate 80%) photocatalytic activity for removing important pollutants, such as methyl orange dyestuff. Consequently, the CeO2 film doped with Cd can be readily reused for five cycles without a notable alteration in photocatalytic activity.
Citation Count: 11
The effect of the structural, optical, and surface properties of anatase-TiO₂ film on photocatalytic degradation of methylene blue organic contaminant
(Springer Heidelberg, 2019) Cergel, Muge Soyleyici; Söyleyici Çergel, Müge; Atay, Ferhunde; Tıbbi Görüntüleme Teknikleri / Medical Imaging Techniques
TiO2 film was prepared onto glass substrates with ultrasonic spray pyrolysis technique by using the less reported Ti (IV) chloride precursor, and then a highly anatase TiO2 film was successfully produced by annealing at 550 degrees C for 3 h in air. The structural, optical, and surface properties were characterized in detail by means of X-ray diffraction (XRD) patterns, UV-vis spectroscopy, spectroscopic ellipsometry, photoluminescence spectrometry, atomic force microcopy (AFM), and energy dispersive X-ray (EDX) spectroscopy. Furthermore, to investigate the application potential as a catalyst, the photocatalytic property of TiO2 film was tested by the degradation of methylene blue dye at various time intervals under UV light. It was determined that photocatalytic degradation of methylene blue using TiO2 film has the highest correlation with first-order velocity law, and the degradation efficiency was successfully achieved at 66.1% after 1 h. Consequently, an alternative, inexpensive, easily applicable, and highly efficient material was developed for the removal of organic dyes in wastewater.
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: 13
Electrochemical Evaluation of the Total Antioxidant Capacity of Yam Food Samples on a Polyglycine-Glassy Carbon Modified Electrode
(Bentham Science Publ Ltd, 2020) Demir, Ersin; Senocak, Ahmet; Tassembedo-Koubangoye, Mouhoum F.; Demirbas, Erhan; Aboul-Enein, Hassan Y.
Background: The total antioxidant capacity of yam food grown in southern African regions was investigated by a polyglycine-glassy carbon modified electrode. The modified electrode was fabricated using glycine solution on glassy carbon electrode by electrodeposition method. The proposed modified electrode is found to be nearly 3.15-fold more sensitive than the bare electrode. For the measurement of the total antioxidants of yam, differential pulse stripping voltammetry (DPSV) was employed with standard quercetin compound. Methods: The total antioxidant capacity of yam was deduced by DPSV and cyclic voltammetry (CV) methods. The basic parameters for the stripping technique such as pH, accumulation time and accumulation potential were optimized as 20 s, 200 mV and a pH of 3 Britton-Robinson (B-R) buffer solutions in 0.5 mg quercetin/L, respectively. Results: In the optimization condition, the linear working range was determined between 5.0 mu g/L and 80.0 mu g/L for the quercetin. The detection (LOD) and quantification (LOQ) limits of quercetin were found to be 0.39 mu g/L and 1.39 mu g/L on the modified electrode by DPSV, respectively. The procedure was also applied to natural yam samples and total antioxidant capacity of 0.1 kg of yam was determined as 96.15 +/- 0.85 mu g/L of equivalent quercetin at 95% confidence level with the relative standard deviations of 0.88%. Conclusion: Sensitive and selective voltammetric method was developed for the determination of total antioxidant capacity in yam. Moreover, the modified polyglycine-glassy carbon electrode was constructed more selectively for quercetin. As a result, a simple, sensitive and rapid new voltammetric method for the determination of antioxidants has been developed using the modified electrode.
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: 3
Fe³⁺ - Ion Selective Electrode Developed as a Detector in Flow Injection Analysis
(Bentham Science Publ Ltd, 2015) Demir, Ersin; Kemer, Baris; Isildak, Ibrahim; Aboul-Enein, Hassan Y.
A new polyvinyl chloride (PVC) membrane Fe3+ - ion selective electrode was constructed as a detector for the analysis Fe3+ using a home-made low-volume flow through cell. Optimum working conditions for the flow injection analysis (FIA) measurements were examined. In addition, under optimum conditions, potentiometric performance characteristics of the Fe3+ ion-selective electrode were investigated. Electrode had a linear response in the concentration range of 1.0 x 10(-3)-1.0 x 10(-6) M (R-2=0.9961, y=24.7+772.0). Reproducibility of the electrode responses was very satisfied. The potential of Fe3+ ion selective electrode was decreased intra and inter day 0.9 % and 3.7% respectively. The designed flow-through cell system as Fe3+ detector revealed sampling rates of approximately 50 injections per hour. The obtained results in FIA were in a good agreement with AAs results at % 95 confidence level for each syrups.
Kahve çekirdeği kavurma derecelerinin Türk kahvesi, filtre kahve ve espressodaki antioksidan kapasitesine etkisinin elektrokimyasal yöntemle belirlenmesi ve gastronomik açıdan değerlendirilmesi
(2022) Gök, İlkay; Gök, İlkay; Demir, Ersin; Gastronomi ve Mutfak Sanatları / Gastronomy and Culinary Arts
Ülkelere, kültürlere ve yaşam şekillerine göre değişen birçok pişirme/demleme tekniği ile insanların hayatlarında önemli bir yeri olan kahve, dünyadaki içecek tüketiminin %75'ini oluşturmaktadır. Yapılan araştırmalar, dünya genelinde günde 2.25 milyar fincan kahve içildiğini göstermektedir. Kahvenin insan hayatındaki yerinin bu denli büyük olmasının sağlık üzerindeki etkileri hakkında birçok çalışma yapılmış olsa da kahve tüketiminin gün geçtikçe artması ve farklı demleme/pişirme tekniklerinin de ortaya çıkması nedeniyle yeni yapılacak olan çalışmalara ihtiyaç vardır. Kahve, serbest radikal süpürme özelliğine sahip ve insan sağlığı için yararlı bileşikleri barındırması bakımından oldukça zengin bir besin kaynağıdır. Biyolojik olarak aktif bileşiklerin bol miktarda bulunması hem doğal yapısındaki bileşiklerden hem de geçirmiş olduğu işlemlerden sonra oluşan kahve içeceklerinin antioksidan kapasitesinden geldiği bilinmektedir. Bu çalışmanın amacı farklı kavurma derecelerindeki kahve çekirdeklerinin farklı teknikler ile demlenmesi sonucunda antioksidan kapasitelerindeki değişimlerin incelemesidir. Çalışmada; Kolombiya, Guatemala ve Kosta Rika'da yetişen çekirdeklerden oluşturulan karışım kahve çekirdeği; açık, orta ve koyu kavurma şekline kavrulmuş ve espresso, filtre kahve ve Türk kahvesi yöntemleri ile demlenmiş/pişirilmiştir. Demlenen kahve çeşitlerinin içerisindeki antioksidan kapasitelerinin değişimleri, kare dalga sıyırma (SWSV), diferansiyel puls sıyırma (DPSV) ve dönüşümlü voltametrik (CV) elektrokimyasal yöntemleri ile incelenmiştir. Kahve numunelerinin eşdeğer miktarlar açısından antioksidan kapasiteleri, optimum koşullar altında pH 4.0'da yaklaşık 0.4 V'de pik potansiyelinde rutin ve kafeik asidin standart oksidasyon elektrot tepkimesine göre belirlenmiştir. Maksimum antioksidan kapasite, espresso ile hazırlanan açık kavurma kahve örneğinde elde edilmiştir. Toplam antioksidan miktarı camsı karbon elektrot (GCE) üzerinde SWSV ile rutin ve kafeine eşdeğer miktar olmak üzere sırasıyla 9.358±0.166 g/L ve 19.700±0.746 g/L olarak hesaplanmıştır. Bununla birlikte, filtre kahvenin orta derecede antioksidan aktivite içerdiği ve Türk kahvesinin ise en düşük antioksidan aktiviteye sahip olduğu SWSV, DPSV ve CV yöntemleri ile belirlenmiştir.
Citation Count: 15
A Novel all Solid-State Contact PVC-Membrane Beryllium-Selective Electrode Based on 4-Hydroxybenzo-15-Crown-5 Ether Ionophore
(Bentham Science Publ Ltd, 2018) Isildak, Ibrahim; Attar, Azade; Demir, Ersin; Kemer, Baris; Aboul-Enein, Hassan Y.
Aim: A novel all solid-state contact PVC-membrane beryllium-selective electrode based on 4-hydroxybenzo-15-crown-5 ether as an ionophore is described. Results: The best performance was obtained with a membrane composition of 4% ionophore, 67% dioctyl sebacate (DOS), 28% poly(vinyl chloride) (PVC), and 1% potassium tetrakis (p-chloro) phenylborate (KTClPB) (w/w). The all solid-state contact PVCmembrane beryllium-selective electrode together with an Ag/AgCl reference electrode exhibited sub-Nernstian response with a slope of 22 +/- 1 mV/decade to beryllium ions from 1.0x10(-6) to 1.0x10(-1) M, and resulted a considerably low detection limit of 6.2x10(-7). The electrode had a good performance in selectivity over a wide range of interfering cations tested. It showed a working pH range between 4.0-8.2 with fast response time (< 10 s) and a good reproducibility. Conclusion: The all solid-state contact PVC-membrane beryllium-selective electrode developed was successfully applied in potentiometric titration of Be2+ ions with EDTA.
Citation Count: 11
A Novel Iron(III)-Selective Membrane Potentiometric Sensor Based on 5-Chloro-3-[4-(trifluoromethoxy) phenylimino] Indolin-2-one
(Bentham Science Publ Ltd, 2015) Demir, Ersin; Kemer, Baris; Bekircan, Olcay; Aboul-Enein, Hassan Y.
A novel polyvinyl chloride (PVC) membrane sensor that is highly selective to Fe3+ ions was prepared by using 5-chloro-3-[4-(trifluoromethoxy) phenylimino] indolin-2-one (CFMEPI) ionophore. The sensor exhibits a Nernstian response for Fe3+ ions over a wide concentration range (1.0 x10(-2) -1.0x10(-6)M) with a slope of 46.7 +/- 0.5 mV per decade. The sensor has a response time of 20s and can be used for at least 3 months without any measurable divergence in potential. It was concluded that the sensor response was pH independent in the range of 4.0-8.61. The sensor has some advantages such as short analysis time, particularly high selectivity towards iron (III). The sensor was used successfully for direct determination of Fe3+ in several synthetic and real samples with satisfactory results.
Citation Count: 3
A novel potentiometric pH electrode based on sulfated natural Fe₃O₄ and analytical application in food samples
(Springer, 2018) Kemer, Baris; Demir, Ersin
A novel solid state potentiometric pH electrode based on sulfated natural Fe3O4 silicone was fabricated. The optimum potentiometric performances such as Nernstian response, response time, selectivity, life-time and reproducibility of pH electrodes were investigated by using a computer-controlled potentiometric device. Moreover, the potentiometric performance of the solid state pH electrodes was studied with different mixtures sulfated natural Fe3O4, silicone and graphite powder. The best potentiometric behavior of proposed pH electrode was obtained with a composition of 20% (w/w) sulfated natural Fe3O4, 40% (w/w) graphite powder and 40% (w/w) silicone. The sub-Nernstian response for pH electrode was exhibited with a slope of 30.8 +/- 1.4mV/pH (r=0.9963) from pH 2 to pH 12. In addition, the dynamic response time was found as 10s in acidic medium and further the proposed pH electrode can be used for at least 1year without any significant slope of the pH-potential curve. The selectivity coefficient of pH electrode was interpreted according to fixed interference method in the presences of Na+, Li+, K+, NH4+, SO42, CH3COO and NO3 ions. The reproducibility of pH electrode was calculated in pH 4 and pH 6 phosphate buffers and it was found as 0.24 RSD (%) and 0.27 RSD (%) respectively. The proposed pH electrode was used to determine of pH in acidbases titration compared with glass pH electrode and is highly stable in corrosive systems including HF solution. Terminally, the pH value was successfully determined in some soft drinks and milk samples by proposed solid state pH electrode at 95% confidence level with satisfactory agreement compared with glass pH electrode.
Citation Count: 2
RETRACTED: Use of electrochemical methods to determine the effect of brewing techniques (Espresso, Turkish and Filter coffee) and roasting levels on the antioxidant capacity of coffee beverage (Retracted Article)
(Springer india, 2023) Yildirim, Sevinc; Gök, İlkay; Gök, İhsan; Aboul-Enein, Hassan Y.; Gastronomi ve Mutfak Sanatları / Gastronomy and Culinary Arts
Coffee is a complex mixture of chemicals, which provide biologically active compounds with various health benefits. The some biologically active compounds arising from both its natural structure and formed after processing were determined as an antioxidant capacity of coffee beverages. In this study, we aimed to determine how roasting levels of Arabica coffee seed (light, medium, dark) and three brewing techniques-decoction methods (Turkish coffee), infusion method (filter coffee) and pressure methods (Espresso)-affect total antioxidant capacity in a cup of coffee beverage by electrochemical methods such as square wave stripping voltammetry (SWSV), differential pulse stripping voltammetry (DPSV) and cyclic voltammetry (CV). Antioxidant capacities of the coffee samples in terms of the equivalent amounts were determined according to standard oxidation peaks of rutin and caffeic acid. The highest antioxidant capacity was found in espresso coffee prepared at light roasting coffee seeds as equivalent the routine and caffeic at 9.4 +/- 0.2 g/L and 19.7 +/- 0.7 g/L, respectively with SWSV on a carbon paste electrode. As a result, SWSV, DPSV and CV voltammetric methods, fast, reliable, fully validated and without any pretreatment are alternative to conventional analytical methods to evaluation antioxidant values in any food samples.
Citation Count: 0
RETRACTION: Use of electrochemical methods to determine the effect of brewing techniques (Espresso, Turkish and Filter coffee) and roasting levels on the antioxidant capacity of coffee beverage (Retraction of Vol 60, Pg 1933, 2023)
(Springer india, 2024) Yildirim, Sevinc; Demir, Ersin; Gök, İhsan; Gok, Ilkay; Aboul-Enein, Hassan Y.
[No Abstract Available]
Citation Count: 8
Sensitive and Selective Pathway of Total Antioxidant Capacity in Commercially Lemon, Watermelon and Mango-pineapple Cold Teas by Square Wave Adsorptive Stripping Voltammetry
(Gazi Univ, 2019) Demir, Ersin
The present work describes a convenient method for the sensitive and selective pathway of total antioxidant capacity (TAC) in lemon, watermelon and mango-pineapple cold teas by square wave adsorptive stripping voltammetry (SWAdSV) that is major electroanalytical methods on a carbon paste electrode. Anodic peak current of p-coumaric acid exhibited a well oxidation peak at 780 mV was used as a standard to evaluate TAC in tea samples. In addition, the very well-resolved and reproducible anodic processes, such as accumulation time, frequency, step potential etc. were optimized for the SWAdSV method. The potential applicability of the proposed SWAdSV was illustrated in commercial teas samples. SWAdSV proved to be a faster and easier method to calculate TAC compared to other conventional methods. Furthermore, total antioxidant amounts of commercially lemon, watermelon and mango-pineapple cold teas were found in optimum condition as equivalent to a concentration of 2050 +/- 15mg/L, 705 +/- 10 mg/L and 808 +/- 14 mg/L p-coumaric acid (n=3, 95% confidence level), respectively.
Citation Count: 13
A Simple and Sensitive Square Wave Stripping Pathway for the Analysis of Desmedipham Herbicide by Modified Carbon Paste Electrode Based on Hematite (α-Fe₂O₃ Nanoparticles)
(Wiley-v C H verlag Gmbh, 2019) Demir, Ersin
In the present study, desmedipham, used as an herbicide to control broad leaf weed in commonly sugar beet crops, was analyzed at the first time by cyclic voltammetry (CV) and square wave stripping voltammetry (SWSV) with the modified carbon paste electrode based on hematite nanoparticles (alpha-Fe2O3-CPE). The modified alpha-Fe2O3-CPE prepared by hematite (alpha-Fe2O3 nanoparticles), which is very sensitive to carbon paste electrode (CPE) and glassy carbon electrode (GCE). Morphology of electrode surface detailed by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The oxidation of desmedipham created irreversible well-done two peaks at nearly +1.1 and +1.3 V. In order to obtain the best calibration graph, various important parameters such as pH, accumulation time, puls amplitude and frequency etc. were investigated. Under the optimum conditions, electrochemical behavior of desmedipham presented two linear working ranges at 0.15-1.20 mg/L and 1.20-4.50 mg/L. The limits of detection (LOD) for the desmedipham were calculated as 41.00 and 50.00 mu g/L for the peak I and II, respectively. Furthermore, desmedipham was analyzed at high recovery in the presence of rizolex, fluometuron, teflubenzuron and some heavy metal ions. Consequently, the developed SWSV was successfully applied to evaluate desmedipham in spiked commercial strawberry juices at recoveries of 96.00-104.00 % with satisfactory relative standard deviations.
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: 2
Use of electrochemical techniques for determining the effect of brewing techniques (espresso, Turkish and filter coffee) and roasting levels on total antioxidant capacity of coffee beverage
(Wiley, 2022) Yildirim, Sevinc; Gök, İlkay; Gök, İhsan; Tokusoglu, Ozlem; Gastronomi ve Mutfak Sanatları / Gastronomy and Culinary Arts
In this study, we determined how roasting levels (light, medium, and dark) of Arabica coffee seed and three brewing techniques-decoction methods (Turkish coffee), infusion method (filter coffee), and pressure methods (Espresso)-affect the total antioxidant capacity in a cup of coffee beverage by electrochemical methods such as square wave stripping voltammetry (SWSV), differential pulse stripping voltammetry (DPSV), and cyclic voltammetry (CV). The highest antioxidant capacity was found in espresso coffee prepared with light roasted coffee seeds, as equivalent of rutin and caffeic acid at 9.4 +/- 0.2 g/L and 19.7 +/- 0.7 g/L, respectively with SWSV on a carbon paste electrode (CPE). The antioxidant capacity of coffee beverages was influenced by the roasting degree, extraction time, and brewing methods, significantly. SWSV, DPSV, and CV voltammetric methods, fast, reliable, fully validated and without any pretreatment, are alternatives to conventional analytical methods for evaluation of antioxidant values in coffee brews. Practical applications This research will contribute to the literature considerably since we have established that the antioxidant capacity can be measured by electrochemical methods rapidly with high reliable results. According to the study, the brewing method and roasting temperature significantly affected the antioxidant capacity, and thus, it is important to know how brewing methods, roasting temperatures, and other conditions changes the coffee quality. The results can be used to prepare healthy coffee beverages.