Catarina Mansilha

Quantification of endocrine disruptors and pesticides in water by gas chromatography–tandem mass spectrometry. Method validation using weighted linear regression schemes

A multi-residue methodology based on a solid phase extraction followed by gas chromatography-tandem mass spectrometry was developed for trace analysis of 32 compounds in water matrices, including estrogens and several pesticides from different chemical families, some of them with endocrine disrupting properties. Matrix standard calibration solutions were prepared by adding known amounts of the analytes to a residue-free sample to compensate matrix-induced chromatographic response enhancement observed for certain pesticides. Validation was done mainly according to the International Conference on Harmonisation recommendations, as well as some European and American validation guidelines with specifications for pesticides analysis and/or GC-MS methodology. As the assumption of homoscedasticity was not met for analytical data, weighted least squares linear regression procedure was applied as a simple and effective way to counteract the greater influence of the greater concentrations on the fitted regression line, improving accuracy at the lower end of the calibration curve. The method was considered validated for 31 compounds after consistent evaluation of the key analytical parameters: specificity, linearity, limit of detection and quantification, range, precision, accuracy, extraction efficiency, stability and robustness.

Monitoring pesticide residues in greenhouse tomato by combining acetonitrile-based extraction with dispersive liquid-liquid microextraction followed by gas-chromatography-mass spectrometry.

A multiclass and multiresidue method for pesticide analysis in tomato was validated. Extraction and pre-concentration of the pesticide residues from acetonitrile extracts was performed by using dispersive liquid-liquid microextraction (DLLME) technique, followed by gas chromatography-mass detection. DLLME was performed using carbon tetrachloride as extractive solvent and acetonitrile extract as dispersive solvent, in order to increase enrichment factor of the extraction procedure. Validation parameters indicated the suitability of the method for routine analyses of thirty pesticides in a large number of samples. In general, pesticide recoveries ranged between 70% and 110% and repeatability ranged between 1% and 20%. The proposed method was applied to the monitoring of pesticides in tomatoes grown during winter in greenhouses. Among the compounds considered in this work, cyprodinil was found in tomato at concentrations of 0.33mg/kg, other pesticides like azoxystrobin, fenhexanid, tolyfluanid, λ-cyhalothrin and trifloxystrobin were also detected, but, not quantified.

Optimization of Conditions for Anthocyanin Hydrolysis from Red Wine Using Response Surface Methodology (RSM)

Optimization of conditions for anthocyanin hydrolysis from red wine was investigated using response surface methodology. The aglycon forms of the anthocyanins were quantified by high-performance liquid chromatography with diode array detection. The combined effects of three independent variables, HCl amount, heating temperature, and hydrolysis time, were studied using a 2(3) full-factorial central composite design. Anthocyanin hydrolysis yield depended mainly on the heating temperature and time of hydrolysis. HCl amount was the factor that least influenced the hydrolysis of anthocyanins. From experimental results, the maximum yield of anthocyanidins was reached with 9.8 mL of HCl (32% v/v), a heating temperature of 166.2 °C, and a hydrolysis time of 46.6 min. Five anthocyanidins, namely, delphinidin, cyanidin, petunidin, peonidin, and malvidin, were quantified in red wine. The reliability of the method was confirmed by recovery experiments, performed under optimal conditions. Recoveries indicated that anthocyanidins resisted the hydrolysis conditions.

Bathing waters: New directive, new standards, new quality approach

Bathing water quality is an important public health issue, mainly because of fecal contamination. In 2006, the European Commission (EC) adopted a new directive with respect to recreational bathing waters that calls for stricter standards and reduces the number of laboratory tests done in routine beach monitoring from nineteen to two bacterial indicators, namely, Escherichia coli and intestinal enterococci, replacing policies of the EC Bathing Water Directive that have existed since 1976. Our practice in Portugal is in line with this international development, and this study demonstrates the equivalency of the new bacteriological parameters with the old. The water quality of 25 coastal beaches was surveyed using both new and old microbiological indicators of fecal contamination. Statistical analysis demonstrated equivalency of the results obtained for fecal coliforms with Escherichia coli and for fecal streptococci with intestinal enterococci.

Water Quality Concerns Due to Forest Fires: Polycyclic Aromatic Hydrocarbons (PAH) Contamination of Groundwater From Mountain Areas

Water quality alterations due to forest fires may considerably affect aquatic organisms and water resources. These impacts are cumulative as a result of pollutants mobilized from fires, chemicals used to fight fire, and postfire responses. Few studies have examined postfire transport into water resources of trace elements, including the polycyclic aromatic hydrocarbons (PAH), which are organic pollutants produced during combustion and are considered carcinogenic and harmful to humans. PAH are also known to adversely affect survival, growth, and reproduction of many aquatic species. This study assessed the effects of forest wildfires on groundwater from two mountain regions located in protected areas from north and central Portugal. Two campaigns to collect water samples were performed in order to measure PAH levels. Fifteen of 16 studied PAH were found in groundwater samples collected at burned areas, most of them at concentrations significantly higher than those found in control regions, indicating aquifer contamination. The total sum of PAH in burned areas ranged from 23.1to 95.1 ng/L with a median of 62.9 ng/L, which is one- to sixfold higher than the average level measured in controls (16.2 ng/L). In addition, in control samples, the levels of light PAH with two to four rings were at higher levels than heavy PAH with five or six rings, thus showing a different profile between control and burned sites. The contribution of wildfires to groundwater contamination by PAH was demonstrated, enabling a reliable assessment of the impacts on water quality and preparation of scientifically based decision criteria for postfire forest management practices.

Interlaboratory validation of an environmental monitoring method for trace analysis of endocrine disrupting compounds

Environmental pollution continues to be an emerging study field, as there are thousands of anthropogenic compounds mixed in the environment whose possible mechanisms of toxicity and physiological outcomes are of great concern. Developing methods to access and prioritize the screening of these compounds at trace levels in order to support regulatory efforts is, therefore, very important. A methodology based on solid phase extraction followed by derivatization and gas chromatography-mass spectrometry analysis was developed for the assessment of four endocrine disrupting compounds (EDCs) in water matrices: bisphenol A, estrone, 17β-estradiol and 17α-ethinylestradiol. The study was performed, simultaneously, by two different laboratories in order to evaluate the robustness of the method and to increase the quality control over its application in routine analysis. Validation was done according to the International Conference on Harmonisation recommendations and other international guidelines with specifications for the GC-MS methodology. Matrix-induced chromatographic response enhancement was avoided by using matrix-standard calibration solutions and heteroscedasticity has been overtaken by a weighted least squares linear regression model application. Consistent evaluation of key analytical parameters such as extraction efficiency, sensitivity, specificity, linearity, limits of detection and quantification, precision, accuracy and robustness was done in accordance with standards established for acceptance. Finally, the application of the optimized method in the assessment of the selected analytes in environmental samples suggested that it is an expedite methodology for routine analysis of EDC residues in water matrices.

Application of a fast and cost-effective in situ derivatization method prior to gas chromatography with mass spectrometry to monitor endocrine disruptors in water matrices.

This work deals with the optimization of a rapid, cost-effective, and eco-friendly gas chromatography with mass spectrometry method for the simultaneous determination of four endocrine disruptor compounds in water matrices: estrone, 17β-estradiol, 17α-ethinylestradiol, and bisphenol A, that are currently considered to be of main concern in the field of water policy and that could became candidates for future regulations. The method involves simultaneous derivatization and extraction of compounds by dispersive liquid-liquid microextraction followed by gas chromatography with mass spectrometry analysis. Derivatization and extraction parameters were optimized with the aid of experimental design approach. An excellent linear response was achieved for all analytes (r(2) ≥ 0.999). Limits of detection and quantification are 0.003-0.005 and 0.0094-0.0164 μg/L, respectively. Intraday precision ranged between 1.1 and 12.6%, whereas interday precision ranged between 0.5 and 14.7%. For accuracy, bias values varied between -15.0 and 13.7%. Recoveries at three concentration levels ranged from 86.4 to 118.2%. The proposed method can be applied to the routine analysis of groundwater, river, sea, tap, and mineral water samples with excellent sensitivity, precision, and accuracy.

Impact of Freezing on Flavonoids/Radical-Scavenging Activity of Two Onion Varieties

Pinho C., Soares M.T., Almeida I.F., Aguiar A.A.R.M., Mansilha C., Ferreira I.M.P.L.V.O. (2015): Impact of freezing on flavonoids/radical-scavenging activity of two onion varieties. Czech J. Food Sci., 33: 340–345. Flavonols, anthocyanins, and radical-scavenging activity of two Portuguese onion cultivars (Branca da Povoa, white; and Vermelha da Povoa, red) were evaluated simulating domestic freezing conditions (–18°C). Frozen portions of onions with different periods of domestic storage at ambient temperature presented increased flavonoid content when compared with the respective composition before freezing. No significant differences were observed on radicalscavenging activity. Domestic freezing of onion portions extended its shelf life. Thus, domestic freezing can be a good alternative to prevent the loss of unused fresh onions, preserving its antioxidant capacity, since frozen onions can be a useful natural antioxidant source.

Groundwater resources in a Mediterranean mountainous region: environmental impact of road de-icing

Water from mountainous regions is a strategic natural resource. In Mediterranean mountainous regions, which, in many cases, correspond to protected areas, high-altitude roads are often the main threat to the sustainability of water resources. In these regions, the regular socioeconomic functioning requires frequent road de-icing operations which normally consist of spreading NaCl and other chemicals, such as CaCl2, in pavements. The main purpose of this research is to assess the environmental impact of road de-icing on groundwater resources in a Mediterranean mountainous region and to describe it by means of a hydrogeological conceptual model. The research focused in a cross-sectional sector located in Serra da Estrela (Central Portugal), where a hydrogeological inventory was carried out, followed by hydrogeochemical and hydrogeophysical studies. The results clearly identify different hydrogeochemical signatures in polluted (Cl–Na facies and higher EC) and unpolluted (HCO3–Na, Cl–Na, and very low EC). The relation of hydrogeochemistry and altitude is complex and depends on both natural processes (namely, water–rock interaction) and anthropic processes (de-icing operations). The hydrogeophysical survey systematically identified the presence of a pollution plume migrating downstream from roads.

Occurrence of Trihalomethanes in Chlorinated Waters from Different Sources Used for Urban Supply

This work received financial support from the European Union (FEDER funds POCI/01/0145/FEDER/007265) and National Funds (FCT/MEC, Fundacao para a Ciencia e Tecnologia and Ministerio da Educacao e Ciencia) under the Partnership Agreement PT2020 UID/QUI/50006/2013. One of the authors (A. Melo) wishes to thank the Fundacao Ciencia Tecnologia grant SFRH/BPD/86898/2012.