Adsorptive transfer cyclic square-wave voltammetry and HPLC with tandem electrochemical detection - Two novel methods for determination of chili peppers pungency.

The pungency of chili peppers, the most popular hot spice used worldwide, is caused by capsaicinoids (CPDs), the content of which can vary greatly due to varietal differences and growing conditions. For the first time, a novel simple method for the fast determination of CPDs in chili peppers and chili products was developed based on adsorptive transfer cyclic square-wave voltammetry (AdTCSWV), using adsorption of lipophilic CPDs on an unmodified glassy carbon electrode surface from methanolic extracts of chili pepper samples. The CSWV is based on short oxidation of adsorbed CPDs to quinoid products, and their subsequent reduction and re-oxidation to provide specific analytical signals with a linear range from 0.

A novel device for the determination of liposome/water partition coefficients.

A novel, cheap and easy-to-construct device and a simple method for partition coefficient determination in liposome/water system based on modified equilibrium dialysis have been developed. The device consists of two vials separated by a semi-permeable membrane, through which the free form of a low molecular weight substance is transported by shaking assisted diffusion. Five test substances, eugenol, carvacrol, thymol, 4-hydroxybenzyl alcohol (4-HBA) and butylparaben were analyzed after equilibration in aqueous phase by three methods, HPLC-UV, GC-MS and DPV with comparable results.

Non-enzymatic electrochemical determination of cholesterol in dairy products on boron-doped diamond electrode.

Determination of cholesterol in food matrices is essential for quality control concerning the health of consumers. Herein, a simple electrochemical approach for cholesterol quantitation in dairy products is evaluated. The newly developed differential pulse voltammetric method using acetonitrile-perchloric acid mixture as a supporting electrolyte is statistically compared to GC-MS and HPLC-UV.

Novel Screen-Printed Sensor with Chemically Deposited Boron-Doped Diamond Electrode: Preparation, Characterization, and Application.

New screen-printed sensor with a boron-doped diamond working electrode (SP/BDDE) was fabricated using a large-area linear antenna microwave chemical deposition vapor system (LA-MWCVD) with a novel precursor composition. It combines the advantages of disposable printed sensors, such as tailored design, low cost, and easy mass production, with excellent electrochemical properties of BDDE, including a wide available potential window, low background currents, chemical resistance, and resistance to passivation. The newly prepared SP/BDDEs were characterized by scanning electron microscopy (SEM) and Raman spectroscopy.

Electroanalysis of Fentanyl and Its New Analogs: A Review.

The review describes fentanyl and its analogs as new synthetic opioids and the possibilities of their identification and determination using electrochemical methods (e.g., voltammetry, potentiometry, electrochemiluminescence) and electrochemical methods combined with various separation methods.

Carbon fiber brush electrode as a novel substrate for atmospheric solids analysis probe (ASAP) mass spectrometry: Electrochemical oxidation of brominated phenols.

A carbon fiber brush electrode (CFBE) was newly designed and used as a substrate for both controlled potential electrolysis and atmospheric solids analysis probe (ASAP) mass spectrometry. Electropolymerized and strongly adsorbed products of electrolysis were directly desorbed and ionized from the electrode surface. Electrochemical properties of the electrode investigated by cyclic voltammetry revealed large electroactive surface area (23 ± 3 cm) at 1.

Kinetic and structural investigation of the cytokinin oxidase/dehydrogenase active site.

Cytokinins are hormones that regulate plant development and their environmental responses. Their levels are mainly controlled by the cytokinin oxidase/dehydrogenase (CKO), which oxidatively cleaves cytokinins using redox-active electron acceptors. CKO belongs to the group of flavoproteins with an 8α-N1-histidyl FAD covalent linkage.

Structural and functional characterization of a plant S-nitrosoglutathione reductase from Solanum lycopersicum.

S-nitrosoglutathione reductase (GSNOR), also known as S-(hydroxymethyl)glutathione (HMGSH) dehydrogenase, belongs to the large alcohol dehydrogenase superfamily, namely to the class III ADHs. GSNOR catalyses the oxidation of HMGSH to S-formylglutathione using a catalytic zinc and NAD(+) as a coenzyme. The enzyme also catalyses the NADH-dependent reduction of S-nitrosoglutathione (GSNO).

Electrochemical behavior of quinoxalin-2-one derivatives at mercury electrodes and its analytical use.

Derivatives of quinoxalin-2-one are interesting compounds with potential pharmacological activity. From this point of view, understanding of their electrochemical behavior is of great importance. In the present paper, a mechanism of electrochemical reduction of quinoxalin-2-one derivatives at mercury dropping electrode was proposed.

Electrochemical behavior and determination of rutin on modified carbon paste electrodes.

The performances of ionic liquid (1-hexyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imide, IL/CPE) and iron phthalocyanine (IP/CPE) modified carbon paste electrodes in electroanalytical determinations of rutin were evaluated and compared to the performance of unmodified carbon paste electrode (CPE). Cyclic voltammetry (CV), differential pulse voltammetry (DPV), differential pulse adsorptive stripping voltammetry (DPAdSV), and amperometry were used for rutin analysis. The best current responses of rutin were obtained at pH 4.

Electrochemical oxidation of berberine and mass spectrometric identification of its oxidation products.

Electrochemical oxidation of the isoquinoline alkaloid berberine in aqueous medium was studied by cyclic and differential pulse voltammetry at a glassy carbon electrode (GCE). Two anodic peaks of the quaternary form of berberine were observed at +1.2V and +1.

A novel fused-silica capillary dropping mercury electrode with long drop-time and its application on determination of critical micelle concentration.

A novel long drop time mercury electrode has been constructed from common fused-silica capillary (50 μm I.D., 360 μm E.

Electrochemical characterization of repaglinide and its determination in human plasma using liquid chromatography with dual-channel coulometric detection.

A simple, fast and sensitive HPLC method employing dual-channel coulometric detection for the determination of repaglinide in human plasma is presented. The assay involved extraction of repaglinide by ethyl acetate and isocratic reversed-phase liquid chromatography with dual-channel coulometric detection. The mobile phase composition was 50mM disodium hydrogen phosphate/acetonitrile (60:40, v/v), pH of the mobile phase 7.

Determination of antihyperglycemic drugs in nanomolar concentration levels by micellar electrokinetic chromatography with non-ionic surfactant.

A method for the separation of six selected antihyperglycemic (antidiabetic) drugs (tolbutamide, gliclazide, glimepiride, glibenclamide, repaglinide, and glipizide) was developed with use of micellar electrokinetic chromatography. Two non-ionic poly(ethylene glycol)-based surfactants Genapol X-080 and Triton X-114 (reduced) were studied as neutral pseudostationary phases. High alkaline pH 10.