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. To overcome the strong overlap of voltammetric signals caused by calibrated and uncalibrated constituents, unfolded partial least squares with residual bilinearization (U-PLS/RBL) was used. The U-PLS/RBL calibration model was constructed and evaluated using a validation set obtained using a Taguchi design. Satisfactory and unbiased results were obtained with a linear response in the range of 0.78-4.48 μmol L^-1 and recoveries from 82.64% to 121.77%. As far as the authors know, a voltammetric method that simultaneously determines four parabens in complex samples such as sweeteners without any previous pretreatment has not yet been reported in the literature.

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. Samples were collected from June to September of 2011 and again during the same period in 2012. The study covered emerging contaminants of different classes, including hormones, plasticizers, herbicides, triclosan and caffeine. The analytical method for the determination of the compounds was based on solid-phase extraction followed by analysis via liquid chromatography electrospray triple-quadrupole mass spectrometry (LC-MS/MS). Caffeine, triclosan, atrazine, phenolphthalein and bisphenol A were found in at least one of the samples collected in the two sampling campaigns. Caffeine and atrazine were the most frequently detected substances in both drinking and source water. Caffeine concentrations in drinking water ranged from 1.8ngL^-1 to values above 2.0μgL^-1 while source-water concentrations varied from 40ngL^-1 to about 19μgL^-1. For atrazine, concentrations were found in the range from 2.0 to 6.0ngL^-1 in drinking water and at concentrations of up to 15ngL^-1 in source water. The widespread presence of caffeine in samples of treated water is an indication of the presence of domestic sewage in the source water, considering that caffeine is a compound of anthropogenic origin.