Cyclic Voltammetry of Retinol in Surfactant Media and Its Application for the Analysis of Real Samples

Different Aspects of the Voltammetric Detection of Vitamins: A Review

Vitamins comprise a group of organic chemical compounds that contribute significantly to the normal functioning of living organisms. Although they are biosynthesized in living organisms, some are also obtained from the diet to meet the needs of organisms, which is why they are characterized as essential chemical compounds. The lack, or low concentrations, of vitamins in the human body causes the development of metabolic dysfunctions, and for this reason their daily intake with food or as supplements, as well as the control of their levels, are necessary. The determination of vitamins is mainly accomplished by using analytical methods, such as chromatographic, spectroscopic, and spectrometric methods, while studies are carried out to develop new and faster methodologies and techniques for their analysis such as electroanalytical methods, the most common of which are voltammetry methods. In this work, a study is reported that was carried out on the determination of vitamins using both electroanalytical techniques, the common significant of which is the voltammetry technique that has been developed in recent years. Specifically, the present review presents a detailed bibliographic survey including, but not limited to, both electrode surfaces that have been modified with nanomaterials and serve as (bio)sensors as well as electrochemical detectors applied in the determination of vitamins.

Development of a simple and rapid screening method for the detection of 1-(3-chlorophenyl)piperazine in forensic samples

1-(3-chlorophenyl) piperazine (mCPP) is a synthetic drug with hallucinogenic effects that has often been found in seized samples. In this context, easy to use point-of-care tests can be of great value in preliminary forensic analysis. Herein, we proposed a simple, fast, and portable electrochemical method for the detection of mCPP in seized samples. The method is based on the use of disposable screen-printed carbon electrodes (SPCE) and rapid screening procedures by square-wave voltammetry using minimal sample sizes (100 μL). mCPP showed an irreversible electrochemical oxidation process at +0.65 V on SPCE (vs Ag) using 0.04 mol L^-1 Britton Robinson (BR) buffer solution (pH 7) as the supporting electrolyte. The proposed method exhibited a linear correlation (r = 0.998) between peak current and mCPP concentration in the range of 1-30 μmol L^-1 (LOD = 0.1 μmol L^-1). Interference studies were performed for adulterants and other classes of drugs of abuse, which can also be found in seized samples containing mCPP, such as caffeine, amphetamine, methamphetamine, 1-benzylpiperazine, 3,4-methylenedioxymethamphetamine, methylone, mephedrone, ethylone and 3, 4-methylenedioxypyrovalerone. The developed method presents great potential as a rapid and simple screening tool to detect mCPP in forensic samples.

Voltammetric determination of β-carotene in raw vegetables and berries in Triton X100 media

Electrochemical behavior of β-carotene in polar organic media and solubilized systems has been investigated. β-Carotene is irreversibly oxidized at 500 and 920 mV on glassy carbon electrode in 0.1 M LiClO(4) ethanol containing 10% of CH(2)Cl(2). Effect of surfactants (cationic, nonionic and anionic) on voltammetric characteristics of β-carotene oxidation has been evaluated. High concentrations of surfactants facilitate the electrooxidation of β-carotene independently of surfactant type. The increase of oxidation current by 7-11% has been obtained in the presence of nonionic surfactant. The best results have been observed in 10 mM Triton X100 media. The peak current showed a linear dependence with the β-carotene concentration over the range 10-380 μM. The calculated detection limit was 2.5 μM and the quantification limit was 8.3 μM. Liquid extraction of β-carotene with dichloromethane from raw vegetables and berries has been developed. Quantitative determination of β-carotene in real samples using cyclic voltammetry in Triton X100 media combined with preliminary extraction has been carried out. The results obtained are in good agreement with data of nutrient database for standard references.

Glassy carbon electrode modified with multi-walled carbon nanotubes sensor for the quantification of antihistamine drug pheniramine in solubilized systems

A sensitive electroanalytical method for quantification of pheniramine in pharmaceutical formulation has been investigated on the basis of the enhanced electrochemical response at glassy carbon electrode modified with multi-walled carbon nanotubes in the presence of sodium lauryl sulfate. The experimental results suggest that the pheniramine in anionic surfactant solution exhibits electrocatalytic effect resulting in a marked enhancement of the peak current response. Peak current response is linearly dependent on the concentration of pheniramine in the range 200–1500 μg/mL with correlation coefficient 0.9987. The limit of detection is 58.31 μg/mL. The modified electrode shows good sensitivity and repeatability.