Development of an electrochemical sensor for the determina-tion of the total antioxidant capacity in berries based on boron doped diamond

Many antioxidants can be electrochemically oxidized using graphite-based electrodes; nevertheless problems arise due to the strong adsorption of redox species at the sensing area. We have demonstrated that boron doped diamond (BDD) electrodes do not show this property, which can be exploited for the design of a new amperometric sensor for the quantification of antioxidants as “total antioxidant capacity” (AOC). As reference substances hydroquinone (HQ) and 6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid (Trolox) were studied in more detail. The supporting electrolyte was a phosphate buffer solution (PBS, 0.1 mol/L, pH 7.0). The limits of detection (LOD) were 1.5 mg/L and 2.5 mg/L for HQ and Trolox, respectively. The repeatability was 3 % RSD for concentration of 200 mg/L HQ. The method could be applied for the determination of AOC in different berry samples, such as strawberry, blueberry, grape and bramble. A comparison with a standard photometric assay showed good correlation between both methods. The BDD sensor features good reproducibility without fatiguing over at least two months of operation

Supplementary data for article: Mehmeti, E.; Stanković, D. M.; Ortner, A.; Zavašnik, J.; Kalcher, K. Highly Selective Electrochemical Determination of Phlorizin Using Square Wave Voltammetry at a Boron-Doped Diamond Electrode. Food Analytical Methods 2017, 10 (11), 3747–3752. https://doi.org/10.1007/s12161-017-0935-x

Supplementary material for: [https://doi.org/10.1007/s12161-017-0935-x]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2531

Austrian pharmacy students' views, experiences and attitudes on an elective clinical pharmacy teaching event delivered in the English language.

Introduction: The World Health Organisation (WHO) and the International Pharmaceutical Federation (FIP) recommend emphasising clinical education within a balanced pharmacy curriculum. During the summer of 2016 the University of Graz (KFU), sponsored an elective English language teaching event on clinical pharmacy for undergraduate pharmacy students. This project aimed to evaluate the views, experiences and attitudes of Austrian students taking part in this clinical pharmacy teaching event. Methods: A mixed method study using a quantitative questionnaire survey followed by qualitative semi-structured, one-to-one telephone interviews. Results: The response rate to the questionnaire and telephone interview study was 67% (n=20) and 30% (n=6) respectively. Students were satisfied with the teaching event (very good: 90% (n=18); good: (10% (n=2). They felt inspired to learn more about clinical pharmacy in the future (100% (n=20)). Main themes included opportunity, relevance and the desire to shape their own future profession

Supplementary data for the article: Kunpatee, K.; Chamsai, P.; Mehmeti, E.; Stankovic, D. M.; Ortner, A.; Kalcher, K.; Samphao, A. A Highly Sensitive Fenobucarb Electrochemical Sensor Based on Graphene Nanoribbons-Ionic Liquid-Cobalt Phthalocyanine Composites Modified on Screen-Printed Carbon Electrode Coupled with a Flow Injection Analysis. Journal of Electroanalytical Chemistry 2019, 855. https://doi.org/10.1016/j.jelechem.2019.113630

Supplementary material for: [https://doi.org/10.1016/j.jelechem.2019.113630]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3821

Supplementary data for the article: Kunpatee, K.; Chamsai, P.; Mehmeti, E.; Stankovic, D. M.; Ortner, A.; Kalcher, K.; Samphao, A. A Highly Sensitive Fenobucarb Electrochemical Sensor Based on Graphene Nanoribbons-Ionic Liquid-Cobalt Phthalocyanine Composites Modified on Screen-Printed Carbon Electrode Coupled with a Flow Injection Analysis. Journal of Electroanalytical Chemistry 2019, 855. https://doi.org/10.1016/j.jelechem.2019.113630

Supplementary material for: [https://doi.org/10.1016/j.jelechem.2019.113630]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3821

A direct and sensitive electrochemical sensing platform based on ionic liquid functionalized graphene nanoplatelets for the detection of bisphenol A

A simple electrochemical sensor for bisphenol A (BPA) was developed based on a composite of graphene nanoplatelets (GNPs) and 1-butyl-2, 3-dimethylimidazolium tetrafluoroborate (ionic liquid, IL) as a modifier for glassy carbon paste electrodes (GCPEs). Scanning electron (SEM) and atomic force microscopy (AFM) were employed to characterize the morphology and surface modification. The electrochemical behavior of BPA on IL-GNP/GCPEs was investigated and the results showed that IL-GNP composites enhance the electrochemical signal toward BPA due to the synergetic effect of GNPs and IL. The experimental parameters including the amount of IL and GNPs, pH of solution, pulse potential, step potential, and scan rate were optimized. Under optimal conditions, the proposed sensor exhibited a linear relationship between signal and BPA concentrations ranging from 0.02–5.0 μM, with detection and quantification limits of 6.4 nM and 0.02 μM respectively. Moreover, the electrochemical sensor showed good repeatability (RSD = 3.3%, n = 5 measurements), good reproducibility (RSD = 3.8%, n = 5 sensors), high accuracy of 95.3–104.5% recovery, acceptable selectivity, and stability. The sensor was successfully applied to the determination of BPA in water samples in contact with plastic materials. The results were satisfactory and in agreement with reference values from a standard HPLC method.This is the peer-reviewed version of the following article: Butmee, P.; Tumcharern, G.; Saejueng, P.; Stanković, D.; Ortner, A.; Jitcharoen, J.; Kalcher, K.; Samphao, A. A Direct and Sensitive Electrochemical Sensing Platform Based on Ionic Liquid Functionalized Graphene Nanoplatelets for the Detection of Bisphenol A. Journal of Electroanalytical Chemistry 2019, 833, 370–379. [https://doi.org/10.1016/j.jelechem.2018.12.014

A direct and sensitive electrochemical sensing platform based on ionic liquid functionalized graphene nanoplatelets for the detection of bisphenol A

A simple electrochemical sensor for bisphenol A (BPA) was developed based on a composite of graphene nanoplatelets (GNPs) and 1-butyl-2, 3-dimethylimidazolium tetrafluoroborate (ionic liquid, IL) as a modifier for glassy carbon paste electrodes (GCPEs). Scanning electron (SEM) and atomic force microscopy (AFM) were employed to characterize the morphology and surface modification. The electrochemical behavior of BPA on IL-GNP/GCPEs was investigated and the results showed that IL-GNP composites enhance the electrochemical signal toward BPA due to the synergetic effect of GNPs and IL. The experimental parameters including the amount of IL and GNPs, pH of solution, pulse potential, step potential, and scan rate were optimized. Under optimal conditions, the proposed sensor exhibited a linear relationship between signal and BPA concentrations ranging from 0.02–5.0 μM, with detection and quantification limits of 6.4 nM and 0.02 μM respectively. Moreover, the electrochemical sensor showed good repeatability (RSD = 3.3%, n = 5 measurements), good reproducibility (RSD = 3.8%, n = 5 sensors), high accuracy of 95.3–104.5% recovery, acceptable selectivity, and stability. The sensor was successfully applied to the determination of BPA in water samples in contact with plastic materials. The results were satisfactory and in agreement with reference values from a standard HPLC method. © 201

Supplementary data for article: Mehmeti, E.; Stanković, D. M.; Ortner, A.; Zavašnik, J.; Kalcher, K. Highly Selective Electrochemical Determination of Phlorizin Using Square Wave Voltammetry at a Boron-Doped Diamond Electrode. Food Analytical Methods 2017, 10 (11), 3747–3752. https://doi.org/10.1007/s12161-017-0935-x

Supplementary material for: [https://doi.org/10.1007/s12161-017-0935-x]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2531

Highly Selective Electrochemical Determination of Phlorizin Using Square Wave Voltammetry at a Boron-Doped Diamond Electrode

A boron-doped diamond electrode was used as an electrochemical sensor for the determination of phlorizin (aka phloridzin, phlorrhizin) using square wave voltammetry (SWV). Phlorizin (Phl) exhibited a well-defined oxidation peak at +0.9 V (versus Ag/AgCl electrode 3 M KCl) in solutions with a pH value of 6.0. Parameters such as pH value and scan rate were optimized for cyclic voltammetry as well as amplitude and frequency for SWV. The sensor gave excellent response with a wide linear dynamic range for concentrations of phlorizin from 3 to 100 mu M with a detection limit of 0.23 mu M and a good repeatability (+/- 0.9%, n = 7 measurements, c = 10 mu M). The effect of interferences by most common compounds was tested, and the method was successfully applied to the determination of the title compound in apple root extracts and urine samples with satisfactory recovery

Hydrothermal synthesis of novel Sm2(MoO4)3 for selective electrochemical detection of pesticide metol in water samples

The rapid advancement of technology over the past decade has resulted in significant transformations within the photography sector. In photographic processes, photosensitive materials are used by photographers to convert latent images into visible ones. Among other photographic developers, Metol has been used as a monochrome photographic chemical for more than 100 years in Europe. Metol (MTL), chemically N-methyl-p-aminophenol sulphate with formula [HOC6H4NH2(CH3)]2SO4, is also used as a corrosion inhibitor, antioxidant, and antimicrobial, and it serves as an intermediary for the medication diloxanide and dyes for fur and hair [1]. Since it is used in the photographic industry, it is released into the water, contaminating ground, and household water. It can be easily found in different water bodies such as rivers, lakes, ponds, and seas. MTL was found to be a cancerogenic organic pollutant with a significant impact on human health, the environment, animals, plants, and water sources [2]. MTL is non-biodegradable and can accumulate in biotic organisms. It is also related to numerous environmental issues, even in low concentrations. Nevertheless, a larger dose of MTL is necessary to have a substantial effect on several health problems, such as cancer, irritable eyes, slowed heartbeat, skin allergies, and harm to the body's internal blood supply [3]. Therefore, developing a straightforward, quick, affordable, sensitive, and practical method for ML detection in aquatic bodies is imperative. In this study, a susceptible and selective sensor for the detection and quantification of nitrogen-organic pollutant Metol (MTL) was developed. For this purpose, samarium-molybdate (Sm2(MoO4)3 nanoparticles were synthesized by organic solvent-free, eco-friendly, low-cost hydrothermal method and used as an excellent modifier with high catalytic efficiency for implementation into the carbon paste. Electrochemical measurements indicate that the developed electrode facilitates electron transfer processes and enriches the catalytic response. The fabricated Sm2(MoO4)3/CPE sensor has a wide linear range of 0.1 to 100 and 100 to 300 μM of MTL with a low detection and quantification limit of 0.047 µM and 0.156 µM at pH 3 in a BRBS, as supporting electrolyte. The results of using this sensor to analyze real water samples from various sources were satisfactory, indicating that this approach can offer an inexpensive, quick, sensitive sensor for ambient MTL monitorin