Electroanalysis Of Paracetamol By A Carbon Paste Electrode Modified By Zinc: Analytical Application In Human Blood

The present work describes the catalytic effect of zinc particles for electroanalysis the paracetamol (PAR). The working electrode was prepared by mixing the zinc with the carbon powder. The voltammetric behavior of paracetamol was studied when an anodic peak to appear at 0.35 V in 0.1 M Na2SO4 solution (pH 12). The peak resulting from the irreversible oxidation of paracetamol on the zinc modified carbon paste electrode (Zn/CPE). The catalytic effect was evaluated by cyclic voltammetry (CV) and square wave voltammetry (SWV). The electrocatalytic behavior of the zinc particles is allotted to its chemical and physical properties. This electrode has a good performance for the electroanalysis of paracetamol. To obtain an electrochemical analysis of paracetamol oxidation at the surface of Zn/CPE, the voltammograms are used in a potential range of - 1.5 V to 1.5 V. More, Zn/CPE can be utilized successfully to ameliorate the electroanalysis of paracetamol at very feeble concentration and with high detection sensitivity. The limit of detection (LD) and quantification (LQ) obtained are respectively 7.52·10-8 mol L-1 and 2.6·10-7 mol L-1. Then the relative standard deviation (RSD) at 2.0·10-5 mol L-1 PAR concentration was 2.88 % for nine repetitions. Afterward, the presented method was used to electroanalysis paracetamol in human blood samples with satisfying results.

An Identification and Study of Amino Acids of Erigeron annuus Herb

Amino acids in the extract of Erigeron annuus herb were determined using an automatic precolumn derivatization with fluorenylmethyl-chloroformate and reversed-phase liquid chromatography with fluorescence and UV Vis detection. This objective is reached with automatic derivatization using o-phthalaldehyde (OPA) for primary amino acids and 9-Fluorenylmethyl chloroformate (FMOC) for secondary amino acids. Then derivatization integrates into high performance liquid chromatography (HPLC). The applied procedure is fast with easily reproduced results. The insufficient knowledge about amino acids composition of herb of Erigeron annuus is the basis for study. This work reports on content of 16 free and bound amino acids (391.41 μg/mg) in the plant raw material and influence’s evaluation of different extraction types on the amino acid profile. The total content of free amino acids was 4.66 μg/mg; proline prevailed (2.498 μg/mg). The total content of bound amino acids was 386.7 μg/mg; proline (146.8 μg/mg), arginine (67.8 μg/mg), phenylalanine (25.8 μg/mg), asparagine (24.3 μg/mg), histidine (20.4 μg/mg), alanine (18.2 μg/mg), serine (16.6 μg/mg), valine (16.0 μg/mg) were the dominant amino acids. Nine amino acids were classified as essential.

Evaluation Of QuEChERS Sample Preparation For Determination Of Benzimidazoles Residues In Meat By UPLC-MS/MS

A liquid chromatographic-tandem mass spectrometric (LC–MS/MS) multi-residue method has been used for the simultaneous quantification and identification of 9 residues and metabolites of benzimidazole derivatives that the most widely used as anthelmintic veterinary drugs of animals. The modified QuEChERS method was used for sample preparation, which was initially developed for pesticide residue analysis. This paper highlights how quick, easy, cheap, effective and rugged the QuEChERS extraction method is. The method was successfully validated according to the 2002/657/EC guidelines. Recovery of analytes was in the range 99 – 110 %. The decission limits (ССα ) were calculated at MRL level for analytes with an established permitted limit as next: 104.5 μg kg-1 (albendazole), 53.2 μg kg-1 (fenbendazole), 54.2 μg kg-1 (flubendazole), 12.1 μg kg-1 (levamisole), 53.9 μg kg-1 (cambendazole), 64.2 μg kg-1 (mebendazole), 52.5 μg kg-1 (parabendazole), 105.8 μg kg-1 (thiabendazole), 234.2 μg kg-1 (triclobendazole). The suitability of the assay has been assessed through InterVal Software by quo data GmbH (Germany). The method achieves high quality of the results, good recovery, repeatabilities, within-lab reproducibilities, and wide analytical scope and has practical benefits, low cost, high sample throughput, little labor used and few lab ware.

Anodic Stripping Voltammetric Determination Of Copper In Multivitamin-Mineral Formulations Using Iodine-Coated Platinum Electrode

In this work, the utilization of the modified iodine-coated polycrystalline platinum electrode as a voltammetric sensor for copper determination in pharmaceutical formulations was reported. The optimized experimental parameters for the determination of copper were using 0.1M KCl as a supporting electrolyte with a scan rate of 50 mV/s, deposition potential of - 0.2 V, and a deposition time of 2 minutes. The anodic peak related to Copper oxidation is centered at about + 0.05 V. The extended detected linear range for the developed method was between 1 ppm and 100 ppm. The anodic current showed excellent linearity with R2 = 0.9986. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.115 ppm and 0.346 ppm, respectively, which attests to the sensitivity of the method. The investigation for the effect of potential interferences from multivitamins tablet ingredients indicated a specific selectivity toward copper and the absence of any electrochemical response toward these components. The developed method was successfully applied to analyze copper and the obtained results were in good agreement with the labeled values, besides that, the statistical tests indicated no significant difference at p = 0.05 with 95 % confidence level.

Determination of Polycyclic Aromatic Hydrocarbons in Agricultural Products

The procedure for the determination of polycyclic aromatic hydrocarbons (PAH) in agricultural products on the example of five crops (rapeseed, sunflower, flax, corn, soybeans) by gas chromatography mass spectrometry (GC-MS) was developed. It was showed the advantage of using binary mixtures of organic solvents "hexanedichloromethane" for PAH extraction. The time of Soxhlet extraction is from 6 to 8 hours at optimized conditions. The fractionation and purification of extracts by column chromatography on deactivated alumina was optimized. The article presents the optimization of sample injection in the programmed temperature vaporization (PTV) mode, parameters of gas chromatographic separation and mass spectrometric detection in determining 16 priority PAH in agricultural products. The recoveries, correctness and accuracy of the proposed method were checked by “spikes” with concentrations 0.5, 1.0, 2.5, 5.0 μg kg-1. The linearity of the method was determined by calibration curves obtained for three measurements of calibration solutions with concentrations of 0.5-100 ng mL-1. The effectiveness of the proposed combination of sample preparation and analysis by PTV-GC-MS was studied for linearity, accuracy, matrix effects and reproducibility. The method was validated by linearity, accuracy, matrix effect and reproducibility.

Mesoporous Silica With Covalently Immobilized Anthracene As Adsorbent For SPE Recovery Of PAHs Pollutants From Highly Lipidic Solutions

Two samples of functionalized mesoporous silica containing anchored anthrylmethylamine groups (SiO2-Ant) have been prepared by surface assembling (1) and one step silane immobilization (2). Both adsorbents can be attributed to bimodal balanced hydrophobic-hydrophilic adsorbents with loading of anthracene groups about 15-33 %. The adsorbents have been used for solid-phase extraction (SPE) of anthracene from organic solvents (acetonitrile, acetone and heptane) and model solutions of lipids (myristic acid and vegetable oil). The obtained results were compared with commercial C18 SPE cartridge. While C18 cartridge recovers anthracene from water-containing media (acetonitrile/water, 1/1), SiO2-Ant cartridges much more efficient in extraction of anthracene from non-polar solvent (heptane). Lipids macrocomponents such as myristic acid and vegetable oil do not decrease the dynamic adsorption capacity and recovery of the model polycyclic aromatic hydrocarbon (PAH) on SiO2-Ant. It was demonstrated that π-π stacking interaction with the analyte determine the selectivity of SiO2-Ant towards of anthracene. This makes SiO2-Ant attractive for selective preconcentration of PAHs from high lipid content objects, such as vegetable oils.

From Colour Catcher® to colorimetric sensors: disposable and cheap devices for inorganic ions determination

We describe disposable and cheap colorimetric devices obtained by fixing classical dyes on the commercial paper sheet known as "Colour Catcher®" (here named under the acronym CC), the product used to prevent color runs in washing machines cycles. These devices can be used as colorimetric sensors for different analytes of environmental and biological interest since the indicator dye, fixed on the solid material, changes its spectral properties (color and hence UV-vis spectrum) upon contact with the analyte. The relationship between the analyte content and the UV-vis spectrum (or RGB values) change of each sensor is provided using a chemometric tool: the Partial Least Squares regression (PLS). Promising results were obtained when applying these sensors to actual samples, so because of their simple preparation with low-cost reagents, they can be effective for application in environmental and food analysis.

Pharmacokinetics Of Chitosan-Ethacridine Adduct In Rats

The objective of this study is to investigate the pharmacokinetics of the chitosan-ethacridine adduct in white rats. It was demonstrated that the kinetics of ethacridine release from adduct are significantly different from that for intraperitoneally introduced ethacridine. When free ethacridine was introduced, 80% of the administered amount was detected in blood of rats in 30 min. This quantity decreased gradually until 20 h, when 1.25% of the administered amount was detected. Contrary, for chitosan-ethacridine adduct, the ethacridine content in the blood slowly increased for 8 h and then decreased. Even after 72 h of the injection, 3% of the injected amount of ethacridine was detected. The experiment demonstrates a significant delay in the release of ethacridine from the chitosan-ethacridine adduct in the blood of treated rats. Thus, a possibility of using chitosan for prolongation of action of the ethacridine as an antiseptic agent was shown.

Voltammetric bienzymatic sensor for sucrose determination in honey

An electrochemical sensor based on nanostructured planar carbon electrodes (nanoSPCE) modified with a SiO2 biocomposite film containing MnO2 particles and enzymes glucose oxidase and invertase was developed. MnO2 particles obtained by electrochemical deposition possessed electrocatalytic activity toward hydrogen peroxide. Glucose oxidase (GOx) and invertase (Inv) were encapsulated into SiO2 film by method of electroassisted deposition. The electrode modified with biocomposite film nanoSPCE/MnO2/GoX/Inv/SiO2 was electroactive toward sucrose. The indicator reaction was oxidation of H2O2 – the product of bienzymatic reaction which was catalyzed by MnO2 on the electrode surface. The linearity range of the calibration graph for the voltametric determination of sucrose using developed modified electrode is 0.017-0.342 mg/ml, the detection limit is 0.006 mg/ml. The obtained nanoSPCE/MnO2/GoX/Inv/SiO2 electrode demonstrated satisfactory stability of the analytical signal during one month of operation. The developed method was used for sucrose determination in the honey samples. The 50-fold molar excess of glucose and fructose does not interfere the determination of sucrose.

Development and Validation of HPLC-MS Method of Determination of Memantine Hydrochloride for Study of Dissolution Profiles

A method for quantitative determination of memantine hydrochloride by HPLC with mass spectrometric detection (HPLC-MS), suitable for the study of dissolution profiles of tablets "Mematon IС" was developed. Chromatographic determination was performed using a mobile phase of methanol - 0.1% (v/v) aqueous solution of formic acid (55:45) on a column of Zorbax Eclipse Plus C18 size 10 cm Ч 4.6 mm (3.5 μm) at a flow rate of 1 ml/min. The linearity interval in the appropriate dissolution media is 35 - 150 % of the normalized content of memantine hydrochloride in the tablet. The method is validated on the parameters of specificity, accuracy, correctness, linearity in the studied range of concentrations, robustness. The stability of the tested solutions and reference solutions in the case of their storage at room temperature for 24 hours was confirmed. It is established that in the case of the study of solutions prepared in a dissolution medium of 0.1 M hydrochloric acid solution pH 1.2, there is a need to preneutralize hydrochloric acid before analysis, because it, as stronger than formic acid, almost completely ionizes all dissolved molecules, which leads to a significant deviation of the linear dependence of the analytical signal on the concentration of the analyte. Neutralization is performed with 0.1 M sodium hydroxide solution, which is added to the sample of the test solution. The release of more than 85 % of memantine hydrochloride in 15 min in all dissolution media indicates the similarity of the dissolution profiles and does not require the calculation of the similarity factor f2.