Contaminants of emerging concern are organic compounds used in large quantities by the society for various purposes. They have shown biological activity at low concentrations, which gives great environmental relevance. The difficulty to detect and quantify contaminants of emerging concern in the environment stimulates the development of appropriate analytical methods. In this work a chemometric approach to positive and negative electrospray ionization (ESI) optimization for the simultaneous determination of contaminants of emerging concern in water samples by liquid chromatography-ion trap-time of flight-high resolution mass spectrometry (LC-IT-TOF-HRMS) was applied. Three types of phase modifiers were used: formic acid, ammonium hydroxide and formic acid/ammonium formate. The effects of operational parameters such as mobile phase modifier concentrations, mobile phase flow rate, heating block temperature and drying gas flow rate were evaluated by the 2 4 − 1 fractional factorial experimental design, resolution IV, in the screening phase and by Doehlert experimental design. Initial factorial experimental design studies indicated that the phase modifier ammonium hydroxide was more efficient compared to the other evaluated modifiers. It provided higher ion intensities to the majority of analytes. Doehlert experimental design allowed finding a region indicative of the optimum experimental conditions for most analytes. The best experimental condition observed was 3.5 mM ammonium hydroxide concentration; 0.0917 mL/min of mobile phase; 300°C heating block temperature; and drying gas at 200 kPa. These optimized parameters resulted in decreased detection limits of the method. The optimized method was applied to the evaluation of water samples coming from the Rio Doce basin -Minas Gerais/Brazil utilizing multivariate exploratory techniques such as principal component analysis and Kohonen neural network. In this way, the use of chemometric approach showed to be a promising way to optimize the simultaneous determination of twentyone contaminants of emerging concern in aqueous matrices by LC-IT-TOF-HRMS using ESI.

A new highly sensitive and environmentally friendly analytical method, using low-temperature partition extraction and ultra-high-performance liquid chromatography with tandem mass spectrometry, without the use of a labeled analyte, was developed and validated to determine and quantify urinary S-phenylmercapturic acid in urine samples. The World Health Organization, in its guidelines for air quality in Europe, recognizes that benzene is carcinogenic to humans and there is no safe level of exposure. Urinary S-phenylmercapturic acid is a sensitive and specific biological marker of exposure to benzene. The new analytical method, extraction, and analysis, were linear in the working range between 0.1 and 200.0 μg/L, precise (relative standard deviation lower than 6.0%), accurate (97.0-105.0%), and sensitive. The method's limits of detection and quantification were 0.02 and 0.084 μg/L, respectively. The recovery with the low-temperature partition extraction was 96.1%, with relative standard deviation less than 3.8%. The method is simple, accurate, and reproducible, and has been successfully applied in the evaluation of nonoccupational exposure to benzene, by urinary S-phenylmercapturic acid in urine samples.

Abstract:The benzene metabolite trans,trans-muconic acid (tt-MA) is widely used as a biological indicator of exposure to this xenobiotic. An analytical method was developed and validated for the determination of urinary tt-MA using solid phase extraction onto a Strata SAX cartridge. The analysis was performed by HPLC with an Aminex HPX-87H ion exclusion column and a UV diode array detector. The sample preparation conditions were optimized using a 2 4´1 factorial design.Comparison of the slopes of standard analytical curves prepared in aqueous solution and urine showed that the biological matrix suppressed the tt-MA signal by around 50%, so the analytical curves were prepared with tt-MA standard at low concentrations in pooled urine. The analytical curves in the range of 5-500 µg¨L´1 showed determination coefficients values (R 2 ) > 0.99 for tt-MA standard in water and R 2 > 0.98 for tt-MA standards in pooled urine. The coefficients of variation obtained using seven replicates were lower than 3.6%, and recoveries of tt-MA from solutions containing 5, 25, 50 and 100 µg¨L´1 of the analyte were in the range 85%-90%, demonstrating the satisfactory precision and accuracy of the method. The limits of detection and quantification were 0.11 and 0.36 µg¨L´1, respectively. The benefits of this new method developed is the possibility of complete chromatographic peak separation for the determination of tt-MA at baseline, without matrix components' interference as normally found in the C18 column. This is the first time that this chromatographic column has been used for the analysis of tt-MA in urine.

RESUMO Este trabalho avaliou a remoção de diclofenaco (DCF), bezafibrato (BZF) e etinilestradiol (EE2) de efluentes de sistema UASB-FBP (reator anaeróbio de manta de lodo seguido de filtro biológico percolador) em fotorreatores UV de lâmpadas imersas (FRI) e emersas (FRE). Os resultados mostram que baixa eficiência de remoção de tais compostos foi obtida em ambos fotorreatores quando se utilizou baixo tempo de contato (~10 min) e baixa concentração inicial de fármacos (0,5 µg.L-1 para EE2, e 21 µg.L-1 para DCF e BZF). O aumento da concentração inicial de DCF (para 20 mg.L-1) e do tempo de contato (para 20 min) resultaram em aumento da eficiência de remoção (de 31 para 83% no FRI e de 36 para 86% no FRE), indicando que compostos dissolvidos presentes no efluente biológico afetaram adversamente a remoção de fármacos nos fotorreatores devido a competição pela radiação UV incidente.