Development of an impedimetric immunosensor to determine microcystin-LR: New approaches in the use of the electrochemical impedance spectroscopy was used in determining to determine kinetic parameters of immunoreactions

The development of new electrochemical immunosensors for the detection of environmental contaminants is of great interest due to their simplicity, high sensitivity, and extended analytical range. Because of the antibody is immobilized on the electrode, it is important to determine its loss of reactivity after immobilization. In this work, two aspects were addressed. First, we developed a new methodology based on electrochemical impedance (EI) to determine the kinetic parameters associated with immunoreactions carried out on the electrode. Second, an electrochemical immunosensor based on electrochemical impedance spectroscopy (EIE) was developed to determine microcystin-LR in drinking water samples. Microcystin-LR determination was based on a label-free non-competitive immunoassay. The electrochemical immunosensor shows a limit of detection (LOD) of 33 pg mL−1 (3.32 × 10−11 mol L−1 or 0.033 μg L−1) which is well below the WHO guideline recommendation of 1 μg L−1 and 40 times better than the LOD obtained using the same antibody in an optimized conventional competitive ELISA assay. In addition, an acceptable accuracy, with recovery percentages close to 100% were found. The label-free immunosensor is a valuable tool to monitor microcystin-LR in drinking water samples and the environment.Fil: Boffadossi, Micaela. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Di Tocco, Aylen. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Lassabe, Gabriel. Universidad de la República; UruguayFil: Pirez Schirmer, Macarena. Universidad de la República; UruguayFil: Robledo, Sebastian Noel. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ingeniería. Departamento de Tecnología Química; ArgentinaFil: Fernandez, Hector. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Zon, María Alicia. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: González Sapienza, Gualberto. Universidad de la República; UruguayFil: Arevalo, Fernando Javier. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentin

Development of Electrochemical Sensors/Biosensors to Detect Natural and Synthetic Compounds Related to Agroalimentary, Environmental and Health Systems in Argentina: A Review of the Last Decade

Electrochemical sensors and biosensors are analytical tools, which are in continuous development with the aim of generating new analytical devices which are more reliable, cheaper, faster, sensitive, selective, and robust than others. In matrices related to agroalimentary, environmental, or health systems, natural or synthetic compounds occur which fulfil specific roles; some of them (such as mycotoxins or herbicides) may possess harmful properties, and others (such as antioxidants) beneficial ones. This imposes a challenge to develop new tools and analytical methodologies for their detection and quantification. This review summarises different aspects related to the development of electrochemical sensors and biosensors carried out in Argentina in the last ten years for application in agroalimentary, environmental, and health fields. The discussion focuses on the construction and development of electroanalytical methodologies for the determination of mycotoxins, herbicides, and natural and synthetic antioxidants. Studies based on the use of different electrode materials modified with micro/nanostructures, functional groups, and biomolecules, complemented by the use of chemometric tools, are explored. Results of the latest reports from research groups in Argentina are presented. The main goals are highlighted.Fil: Granero, Adrian Marcelo. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Fernandez, Hector. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Zon, María Alicia. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Robledo, Sebastian Noel. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ingeniería. Departamento de Tecnología Química; ArgentinaFil: Pierini, Gastón Dario. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Di Tocco, Aylen. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Carrillo Palomino, Roodney Alberto. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Maccio, Sabrina Antonella. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Riberi, Walter Iván. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Arevalo, Fernando Javier. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentin

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Analytical determinations of luteolin

Plants, through the photosynthesis process, produce the substances necessary for all the life cycles of nature, which are called "primary metabolites." Moreover, there are some plants that synthesize, in addition to these, other substances with more specific functions, which are known as "secondary metabolites." It is inside this group that flavonoids are located, whose main function is to protect organisms from damage caused by different oxidizing agents. Luteolin (3,4,5,7-tetrahydroxy-flavone) belongs to the sub-class of flavonoids known as flavones and is one of 10,000 flavonoids currently known, being one of the most bio-active flavonoids. Its various beneficial properties for health, together with the increasing reduction in the use of synthetic antioxidants, make the study of luteolin a very active field. Within this, the quantification of this molecule has become a subject of very special interest given that it is transversal to all fields. In this review article, we aim to give the reader a broad and deep vision of this topic, focusing on the events reported in the last 5 years and covering all possible techniques related to analytical determinations. We will discuss in terms of advantages and disadvantages between techniques, selectivity, sensitivity, costs, time consumption, and reagents as well as in the complexity of operations.Fil: Tesio, Alvaro Yamil. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigación y Desarrollo en Materiales Avanzados y Almacenamiento de Energía de Jujuy - Universidad Nacional de Jujuy. Centro de Investigación y Desarrollo en Materiales Avanzados y Almacenamiento de Energía de Jujuy - Gobierno de la Provincia de Jujuy. Centro de Investigación y Desarrollo en Materiales Avanzados y Almacenamiento de Energía de Jujuy; ArgentinaFil: Robledo, Sebastian Noel. Universidad Nacional de Río Cuarto. Facultad de Ingeniería. Departamento de Tecnología Química; Argentina. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentin

Qualitative and quantitative electroanalysis of synthetic phenolic antioxidant mixtures in edible oils based on their acid-base properties

A simple electroanalytical method using square wave voltammetry at a Pt band ultramicroelectrode to perform a qualitative and quantitative analysis of different synthetic antioxidant mixtures permitted by official regulations in edible oils is proposed. The methodology was based on the comparison of voltammetric signals obtained in acetonitrile + 0.1 M (C4H 9)4NF6P with those recorded in the same reaction medium when different aliquots of (C4H9) 4NOH were added to allow a qualitative differentiation between antioxidants. Firstly, studies on solutions prepared from commercial reagents were carried out. Then, the results obtained were transferred to the analysis of a real matrix, i.e., an edible olive oil. From real samples spiked with a known amount of different synthetic antioxidant mixtures, we could deduce the presence of these antioxidants by comparing results obtained in the neutral medium with those obtained after the successive addition of base. The standard addition method was used to quantify the individually spiked synthetic antioxidants in the real sample. Recovery percentages were between 88% and 118%. The reproducibility was 1.5%, 3.1%, 4.1% and 4.1% in ACN + 0.1 M TBAHFP and 1.5%, 4.6%, 6.6% and 2.5% in Bz/EtOH (1:2) + 0.1 M H2SO4 for TBHQ, BHA, BHT and PG, respectively. The repeatability was 1% for PG in both media. These parameters show a good system performance.Fil: Robledo, Sebastian Noel. Universidad Nacional de Río Cuarto; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Zon, María Alicia. Universidad Nacional de Río Cuarto; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Ceballos, Claudio Daniel. Universidad Nacional de Río Cuarto; ArgentinaFil: Fernandez, Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto; Argentin

Electrochemical oxidation of butein at glassy carbon electrodes

The electrochemical oxidation of flavonoid butein is studied at glassy carbon electrodes in phosphate and citrate buffer solutions of different pH values, and 1M perchloric acid aqueous solutions by cyclic and square wave voltammetries. The oxidation peak corresponds to the 2e, 2H oxidation of the 3,4-dihydroxy group in B ring of butein, given the corresponding quinone species. The overall electrode process shows a quasi-reversible behavior and an adsorption/diffusion mixed control at high butein bulk concentrations. At low butein concentrations, the electrode process shows mainly an adsorption control. Butein surface concentration values were obtained from the charge associated with the adsorbed butein oxidation peaks, which are in agreement with those values expected for the formation of a monolayer of adsorbate in the concentration range from 1 to 5μM. Square wave voltammetry was used to perform a full thermodynamic and kinetics characterization of the butein surface redox couple. Therefore, from the combination of the "quasi-reversible maximum" and the "splitting of the net square wave voltammetric peak" methods, values of (0.386±0.003) V, (0.46±0.04), and 2.7×10s were calculated for the formal potential, the anodic transfer coefficient, and the formal rate constant, respectively, of the butein overall surface redox process in pH4.00 citrate buffer solutions. These results will be then used to study the interaction of butein, and other flavonoids with the deoxyribonucleic acid, in order to better understand the potential therapeutic applications of these compounds.Fil: Tesio, Alvaro Yamil. Universidad Nacional de Rio Cuarto; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Robledo, Sebastian Noel. Universidad Nacional de Rio Cuarto; ArgentinaFil: Fernandez, Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Zon, María Alicia. Universidad Nacional de Rio Cuarto; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin

Quantitative determination of tocopherols in edible vegetable oils using electrochemical ultra-microsensors combined with chemometric tools

We have developed an electroanalytical method to quantify different isomers of tocopherols in edible vegetable oils. The method uses the square wave voltammetry on a carbon fiber disk ultramicroelectrode in benzene/ethanol+0.1 mol L−1H2SO4. Because the oxidation peaks of these natural antioxidants show an important overlapping, we have used two chemometric tools to obtain the multivariate calibration model. One method was the multivariate curve resolution–alternating least square (MCR–ALS), which assumes a linear behavior, i.e., the total signal is the sum of individual signals of components, and another nonlinear method such as artificial neuronal networks (ANNs). From the accuracy and precision analysis between nominal and estimated concentrations by both methods, we could infer that the ANNs method was a good model to quantify tocopherols in edible oil samples. Recovery percentages were between 94% and 99%. In addition, we found a difference of 1.4–6.8% between the total content of tocopherols in edible oil samples and the vitamin E content declared by the manufacturers.Fil: Robledo, Sebastian Noel. Universidad Nacional de Rio Cuarto. Facultad de Ingeniería. Departamento de Tecnología Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zachetti, Vanessa Gimena Lourdes. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Microbiología e Inmunología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zon, María Alicia. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fernandez, Hector. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Simultaneous electroanalytical determination of luteolin and rutin using artificial neural networks

In this study, we propose an electroanalytical method to quantify simultaneously luteolin and rutin, two flavonoids which are present in a pharmaceutical formulation. The methodology is based on square wave voltammetry at glassy carbon electrodes modified with multiwalled carbon nanotubes dispersed in polyethylenimine. Both flavonoids show quasi-reversible surface redox couples in 10% ethanol + 1 mol L−1 HClO4 aqueous solutions, which are defined in potential regions very close to each other. The adsorption process of flavonoids on the modified electrode surface was carried out using an accumulation potential of 0.55 V (vs. Ag/AgCl, 3 mol L−1 KCl), and an accumulation time of 20 min. Considering that luteolin and rutin electrochemical responses show a high degree of overlapping, we processed the electrochemical signals using artificial neural networks. We used a supervised network, feed-forward network with Levenberg-Marquardt back propagation training. Values of 92.6 ± 0.4 and 92 ± 1 mg per tablet were determined by the artificial neural networks methodology for luteolin and rutin, respectively. According to values declared by the manufacturer, differences of 7.4 and 8.0% were calculated for luteolin and rutin, respectively. Results obtained with electroanalytical methodologies were in very good agreement with those obtained by HPLC.Fil: Tesio, Alvaro Yamil. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Robledo, Sebastian Noel. Universidad Nacional de Rio Cuarto. Facultad de Ingeniería. Departamento de Tecnología Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Granero, Adrian Marcelo. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fernandez, Hector. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zon, María Alicia. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Determination of kinetic parameters of the enzymatic reaction between soybean peroxidase and natural antioxidants using chemometric tools

The oxidation of eugenol, isoeugenol and vanillin natural antioxidants catalyzed by the soybean peroxidase enzyme was studied using uv–vis spectroscopy. An experimental design was used to optimize the different variables. The multivariate curve resolution method was used to obtain the profiles of antioxidant absorbance's as a function of time due to uv–vis absorption bands of both antioxidants and the enzymatic reaction product/s show a strong overlap. From these results, apparent Michaelis-Menten constants as well as the kinetic parameters k 1 and k 3 involved in the catalytic cycle of peroxidases were calculated. The antioxidant apparent acidity constants were also determined at different pH's from uv–vis spectrophotometric measurements. Values of k 1 were (0.6 ± 0.1) × 10 5 M −1 s −1 , (2.0 ± 0.2) × 10 5 M −1 s −1 and (7.0 ± 0.5) × 10 6 M −1 s −1 and k 3 (4.0 ± 0.2) × 10 5 M −1 s −1 , (6.0 ± 0.6) × 10 5 M −1 s −1 and (6.0 ± 0.9) × 10 6 M −1 s −1 for eugenol, isoeugenol and vanillin, respectively.Fil: López, Jimena Claudia. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Zon, María Alicia. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Fernandez, Hector. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Granero, Adrian Marcelo. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Robledo, Sebastian Noel. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ingeniería; Argentin

Square wave voltammetry with multivariate calibration tools for determination of eugenol, carvacrol and thymol in honey

The simultaneous determination of eugenol (EU), thymol (Ty) and carvacrol (CA) in honey samples, employing square wave voltammetry (SWV) and chemometrics tools, is informed for the first time. For this purpose, a glassy carbon electrode (GCE) was used as working electrode. The operating conditions and influencing parameters (involving several chemical and instrumental parameters) were first optimized by cyclic voltammetry (CV). Thus, the effects of the scan rate, pH and analyte concentration on the electrochemical response of the above mentioned molecules were studied. The results show that the electrochemical responses of the three compounds are very similar and that the voltammetric traces present a high degree of overlap under all the experimental conditions used in this study. Therefore, two chemometric tools were tested to obtain the multivariate calibration model. One method was the partial least squares regression (PLS-1), which assumes a linear behaviour. The other nonlinear method was an artificial neural network (ANN). In this last case we used a supervised, feed-forward network with Levenberg-Marquardt back propagation training. From the accuracies and precisions analysis between nominal and estimated concentrations calculated by using both methods, it was inferred that the ANN method was a good model to quantify EU, Ty and CA in honey samples. Recovery percentages were between 87% and 104%, except for two samples whose values were 136% and 72%. The analytical methodology was simple, fast and accurate.Fil: Tonello, Natalia Veronica. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Moressi, Marcela Beatriz. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Robledo, Sebastian Noel. Universidad Nacional de Río Cuarto. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: D'eramo, Fabiana. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Marioli, Juan Miguel. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin