RESUMEN
This review approaches how aqueous two-phase systems (ATPS), in their various compositions (e.g., polymer + salt, copolymer + salt, ionic liquid + salt, acetonitrile + salt), can be efficiently used for extraction, preconcentration, and clean-up of analytes in aqueous samples to determine the compounds classified as emerging contaminants (ECs). In the literature, there are some studies using ATPS applied to ECs, like pesticides, pharmaceuticals, illicit drugs, personal care products, alkaloids, and hormones, even when in trace concentrations. The ATPS is an alternative to the conventional liquid-liquid extraction technique. However, it is predominantly composed of water and do not generally use organic solvents and, therefore, is based on the principles of green chemistry. An ATPS approach has a unique advantage because it can extract neutral, anionic, cationic, polar, and nonpolar compounds, even when present simultaneously in the same sample. This review covers how this simple and low environmental impact technique has been employed for the analysis of different classes of emerging contaminants.
RESUMEN
A method of direct analysis for quantification of 15 inorganic elements (P, S, Cl, K, Ca, Mn, Fe, Ni, Cu, Zn, Br, As, Rb, Sr and Pb) in beers by Total Reflection X-Ray Fluorescence (TXRF) was developed. The experimental conditions were optimized. Direct analysis was compared with the acid digestion procedure to evaluate the effect matrix and the results were satisfactory. The evaluation of the accuracy and precision was realized by analysis of two certified reference materials of natural and waste water. For the majority of the elements, good agreement was achieved between the certified value and the value measured in the CRM´s. Low detection limits were obtained and it was adequate to determine trace elements in beers and to quality control Pb and As, whose maximum limits are 200 and 100µgL-1, respectively. The relative standard deviation (RSD%) ranged from 2.4% to 10%. The method was applied to 30 beer samples collected in several regions of Brazil. The concentration ranges (mgL-1) for the studied analytes were: P: (37.40-140.85); S (10.32-50.73); Cl (82.74-281.7); K (183.8-418.5); Ca (9.82-96.0); Mn (0.06-1.42); Fe (0.07-1.57); Ni (< LLD-1.13); Cu (< LLD-0.32); Zn (0.02-1.98); As (< LLD-0.10); Br (0.01-2.04); Rb (< LLD-0.52); Sr (< LLD-0.41) and Pb (< LLD-0.18). Some beer samples showed As and Pb concentrations above the levels established by Brazilian legislation. The developed method is simple, fast, consumes low amounts of reagents and allows the determination of a large number of analytes simultaneously. TXRF proved to be attractive and useful for routine analysis.