Significant improvements in the voltammetric determination of β-carotene (BCA) have been achieved, mainly by the replacement of toxic dichloromethane with acetone and using non-mercury electrode. The respective procedure is based on anodic oxidation of BCA at a gold electrode in the disc configuration, when using square-wave voltammetry in pure acetone (99.8%) with 0.1 mol L-1 LiClO4 as the supporting electrolyte. The method comprises extraction of the analyte from the sample with acetone, thus avoiding the usually used highly toxic solvents. Analytically, it can be characterized by a linear range from 6.0 × 10-6 to 5.9 × 10-4 mol L-1 with regression equation Ipa = 0.0184c -0.1631 and correlation coefficient, R2 = 0.9998, limits of detection and quantification LOD = 1.6 × 10-6 mol L-1 and LOQ = 5.4 × 10-6 mol L-1, respectively; both being obtained at a potential step of 5 mV, with the pulse amplitude of 25 mV, and a frequency of 80 Hz. After optimization, the method was evaluated in series of analyses; namely, with two samples of vegetables and two pharmaceutical preparations (capsules), when the results could be compared to those of a reference spectrophotometric method. Due to a simple instrumentation, including sample preparation, the voltammetric method for the determination of BCA can be recommended as a quick screening assay in food and pharmaceutical analysis.

• MeSH
• beta-karoten MeSH
• elektrochemie MeSH
• elektrody MeSH
• tobolky MeSH
• zelenina * MeSH
• zlato * MeSH
• Publikační typ
• časopisecké články MeSH

Tento učební text je určen studentům specializace Elektroanalytické chemie, během magisterského studia na Fakultě chemicko-technologické Univerzity Pardubice. Impulsem i hlavním důvodem pro jeho sepsání byla potřeba nabídnout studujícím komplexní materiál, který spolu s příslušnými přednáškami budou mít k dispozici pro přípravu ke zkoušce. Může však posloužit i těm, kdo se více zajímají o obor, jenž proslavil československou a českou vědu doslova po celém světě a který tvořil významnou část vědecko-výzkumného odkazu Prof. Heyrovského, našeho dosud jediného laureáta Nobelovy ceny za přírodní vědy.

A novel sensor based on a modification of glassy carbon electrode (GCE) with NH2-functionalized multi-walled carbon nano-tubes (NH2fMWCNTs) is reported and its applicability to the electrochemical sensing of Propafenone (PPF) demonstrated. The electrochemical catalytic activity was also utilized as a sensitive detection method for the investigation of the detailed redox mechanism of PFF using cyclic and and differential pulse voltammetry. The surface morphology of the sensor was investigated by SEM armed with EDX probe. Electrochemical impedance spectroscopy was employed as well to define the electron transfer capability of modified and bare electrodes. Key experimental and instrumental conditions related to electrochemical determination by cyclic, differential pulse, and square wave voltammetry, such as amount of modifier, pH, scan rate, accumulation time and potential were studied and optimized. The results have shown a significant enhancement of the peak current after modifying the electrode; the calibration curves of PPF offering good linearity from 0.1 to 10 μM, limit of quantification (LOQ) being 0.03 μM and limit of detection (LOD) 0.01 μM, both when using DPV technique. The proposed sensor was successfully applied to the determination of PFF in dosage form without any special purification, separation or pre-treatment steps. The results of analyses obtained with the proposed sensor were satisfactory and fully statistically relevant.

• MeSH
• antiarytmika MeSH
• elektrody MeSH
• farmaceutická technologie přístrojové vybavení   metody   MeSH
• impedanční spektroskopie MeSH
• kalibrace MeSH
• koncentrace vodíkových iontů MeSH
• kyslík chemie   MeSH
• lékové formy * MeSH
• limita detekce MeSH
• mikroskopie elektronová rastrovací MeSH
• nanomedicína MeSH
• nanotrubičky uhlíkové chemie   MeSH
• propafenon aplikace a dávkování   MeSH
• uhlík chemie   MeSH
• Publikační typ
• časopisecké články MeSH

• MeSH
• elektrody MeSH
• glukosa analýza   MeSH
• oxidace-redukce MeSH

• MeSH
• elektrody klasifikace   MeSH
• potenciometrie metody   přístrojové vybavení   MeSH

• MeSH
• elektrochemie metody   MeSH
• jodidy analýza   MeSH
• kuchyňská sůl analýza   MeSH
• techniky in vitro MeSH

• MeSH
• arsen analýza   MeSH
• elektrody metody   normy   MeSH
• potenciometrie metody   MeSH