Classifying micropollutants by environmental risk in groundwater using screening analysis associated to a hybrid multicriteria method combining (Q)SAR tools, fuzzy AHP and ELECTRE.

This study aimed to evaluate and monitor pesticides in groundwater of the Serra Geral aquifer, located in the Paraná Basin 3 (southern Brazil), using Liquid Chromatography coupled with a Quadrupole-Time-of-Flight Mass Spectrometer (LC-QTOF MS). A total of 117 samples, collected in three different moments, were analyzed over 36 months. Groundwater samples from 35 wells and four surface water points were monitored in each sampling campaign. A pesticide screening methodology was proposed with the tentative identification of 1607 pesticides and pesticide metabolites. The application of the proposed methodology resulted in the verification of 29 pesticides and pesticide metabolites, 7 as confirmed analytes and 22 as suspect compounds. (Q)SAR in silico predictions and GUS index calculation provided data on the potential environmental risk of the identified compounds, with eight endpoints considered. After in silico predictions, an alternative hybrid multicriteria method was applied, combining the weighting of endpoints of fuzzy AHP and micropollutants classification by environmental risk using ELECTRE. The fuzzy AHP results indicated the greatest importance of mutagenicity among the eight evaluated indicators, while the scarce influence of the physicochemical properties on the environmental risk suggested their exclusion from the model. Accordingly, the ELECTRE results highlighted the prevalence of thiamethoxam and carbendazim as the most dangerous for the environment. The application of the proposed method enabled the selection of the compounds that must be monitored, considering mutagenicity and toxicity predictions for environmental risk analysis.

Simultaneous multi-residue pesticide analysis in southern Brazilian soil based on chemometric tools and QuEChERS-LC-DAD/FLD method.

A simple and straightforward QuEChERS extraction method was proposed for the simultaneous determination of atrazine (ATZ), desethylatrazine (DEA), desisopropylatrazine (DIA), carbaryl (CBL), carbendazim (CBD), and diuron (DIU) in soil with high agricultural activity from southeastern Brazil, using high-performance liquid chromatography-diode-array detection/fluorescence detection. Screening studies carried out by 24 factorial design indicate better recoveries when less sample (1.0 g) and the volume of solvent (2.0 mL of ACN) were applied, compared to the original QuEChERS method. Furthermore, interactions between factors were not negligible in the experimental set, except for ATZ and DIU, in which only water volume influenced their recovery. The influence of the type (primary secondary amine (PSA), C18, and Florisil) and the sorbent amount ratio to the compounds' concentration were also considered. PSA (25 mg) was selected as the best sorbent without losing analytical response. The limits of quantification (LOQ) were estimated to be 5.0 to 15 µg kg-1 in the soil matrix. Analytical performances were consistent with linearity (R2 ≥ 0.998), recovery from 74.7 to 108%, and relative standard deviations (RSD) between 2.6 and 20.2%. Robustness was assessed by fractional factorial Plackett-Burman design. The method is recommended for chemicals that are soluble in water, and it was successfully applied in the analysis of real soil samples containing the analytes in the range of µg kg-1, proving to be suitable for the study of soils strongly impacted by agricultural activity.

Evaluation of a Hollow-Fiber Liquid-Phase Microextraction Technique for the Simultaneous Determination of PPI Drugs in Human Plasma by LC-DAD.

This study involved the development, validation and application of a three-phase hollow-fiber liquid-phase microextraction (HF-LPME) and liquid chromatography with diode array detection (LC-DAD) method for the simultaneous determination of the proton pump inhibitor (PPI) drugs omeprazole, pantoprazole and lansoprazole in human plasma. The evaluation of the HF-LPME parameters was crucial for the determination of the drugs and the conditions selected were: 1-octanol as solvent; phosphate buffer at pH 5 as donor phase; borate buffer at pH 10 as acceptor phase; extraction time of 15 min; stirring at 750 rpm and NaCl was added at 5% (w/v). Validation of the method according to US-FDA recommendations showed a good linear range (0.2-2.0 µg/mL) for all analytes, with a determination coefficient >0.9910. Precision was evaluated using intra- and inter-day assays, which showed relative standard deviations (RSD), <15% for all concentrations, with a limit of quantification (LOQ) of 0.2 µg/mL. Accuracy was also assessed at these concentration levels and was in the range from 80 to 130%. Finally, the sensitive, selective and reproducible HF-LPME/LC-DAD developed method was successfully applied to human plasma samples from patients undergoing therapy with the PPI drugs.

New insight into monitoring degradation products during the TiO2-photocatalysis process by multivariate molecular spectroscopy.

This study focuses on the feasibility of a spectroscopic multivariate method for monitoring the concentration of phenol and its main degradation products during heterogeneous photocatalysis. Phenolic compounds were chosen as model to evaluate the degradation process due to their toxicity and persistence in the environment and also their well-known degradation pathway. The predictive capability of the multivariate method developed by partial least squares regression (PLSR) over the spectral range of 200-350 nm was satisfactory, allowing mean predicted errors below 5.0 % in the simultaneous determination of the target compounds using six latent variables and smoothing spectra. Suitable results were reported for the simultaneous determination of hydroquinone, resorcinol, pyrocatechol, and p-benzoquinone in accordance to the chromatographic method. Characteristics such as simplicity, low cost, and fast data acquisition are remarkable in this procedure, which makes it appropriate for this type of analytical control.