One-step microwave-assisted synthesis of fluorescent carbon quantum dots for determination of ascorbic acid and riboflavin in vitamin supplements.

The synthesis of carbon quantum dots (CQDs) using chemical precursors with different organic groups is a strategy to improve optical properties and expand applications in several fields of research such as Analytical Chemistry. Ascorbic acid and riboflavin are widely used in human food supplementation, making quality monitoring of these vitamin supplements relevant and necessary. In this work, disodium ethylenediaminetetraacetic, sodium thiosulfate and urea were applied to obtain CQDs through a single-step microwave-assisted synthesis.

Simultaneous determination of methyl, ethyl, propyl, and butyl parabens in sweetener samples without any previous pretreatment using square wave voltammetry and multiway calibration.

Parabens are compounds used as chemical preservatives in cosmetics, drugs, and food. Some can cause adverse effects on human health. In this study, a square wave voltammetric method using a glassy carbon electrode was developed for simultaneous determination of methyl, ethyl, propyl, and butyl parabens in sweeteners.

A preliminary nationwide survey of the presence of emerging contaminants in drinking and source waters in Brazil.

This is the first nationwide survey of emerging contaminants in Brazilian waters. One hundred drinking water samples were investigated in 22 Brazilian state capitals. In addition, seven source water samples from two of the most populous regions of the country were evaluated.

Determination of tryptamine in foods using square wave adsorptive stripping voltammetry.

Tryptamine, a biogenic amine, is an indole derivative with an electrophilic substituent at the C3 position of the pyrrole ring of the indole moiety. The electrochemical oxidation of tryptamine was investigated using glassy carbon electrode (GCE), and focusing on trace level determination in food products by square wave adsorptive stripping voltammetry (SWAdSV). The electrochemical responses of tryptamine were evaluated using differing voltammetric techniques over a wide pH range, a quasi-reversible electron-transfer to redox system represented by coupled peaks P1-P3, and an irreversible reaction for peak P2 were demonstrated.

Electrochemical oxidation and electroanalytical determination of xylitol at a boron-doped diamond electrode.

Xylitol is a reduced sugar with anticariogenic properties used by insulin-dependent diabetics, and which has attracted great attention of the pharmaceutical, cosmetics, food and dental industries. The detection of xylitol in different matrices is generally based on separation techniques. Alternatively, in this paper, the application of a boron-doped diamond (BDD) electrode allied to differing voltammetric techniques is presented to study the electrochemical behavior of xylitol, and to develop an analytical methodology for its determination in mouthwash.