Evaluation of a multiresidue method for measuring fourteen chemical groups of pesticides in water by use of LC-MS-MS

Fast and simplified quantitative multiresidue analytical method for pesticides in surface waters by UHPLC-MS/MS with online sample preparation

A quantitative multiresidue analytical method for the simultaneous analysis of current-use agricultural pesticides in surface waters is reported. The method involves minimal sample manipulation and small sample collection volumes (for 1 mL and 5 mL injections) with online sample clean-up and analyte preconcentration on a hydrophilic-lipophilic balance (HLB) column. To our knowledge, this online approach with the use of an HLB column has not yet been reported for multiresidue pesticide analysis in surface waters. Chromatographic separations of isomeric pesticides were achieved through the sequential coupling of C8 and polar endcapped C18 analytical columns. High resolution accurate mass (HRAM) quadrupole Orbitrap spectrometry was performed in full scan mode followed by data-dependent MS/MS fragmentation (FS-ddMS²) with concurrent electrospray ionization in both positive and negative modes. The method was validated for thirty-one (31) diverse current-use pesticides and demonstrated strong linearity (R² > 0.9912) and precision (% RSD <8.4%) with low quantitation limits (average LOQ of 41 ng L^-1). The majority of target analytes experienced minimal matrix effects (<±20%) in fortified environmental water samples. When applied to surface water samples, the method detected fourteen of the target analytes, including twelve herbicides, one insecticide, and one fungicide. This method offers a fast, simple, and reliable approach for the quantitative analysis of diverse current-use pesticides in surface water samples within hours of sample collection in the field. The robust nature of the method may allow for potential application to other types of water and the targeted or untargeted screening of other emerging contaminants.

Water contamination by endocrine disruptors: Impacts, microbiological aspects and trends for environmental protection

Hormone active agents constitute a dangerous class of pollutants. Among them, those agents that mimic the action of estrogens on target cells and are part of the group of endocrine-disruptor compounds (EDCs) are termed estrogenic EDCs, the main focus of this review. Exposure to these compounds causes a number of negative effects, including breast cancer, infertility and animal hermaphroditism. However, especially in underdeveloped countries, limited efforts have been made to warn people about this serious issue, explain the methods of minimizing exposure, and develop feasible and efficient mitigation strategies at different levels and in various environments. For instance, the use of bioremediation processes capable of transforming EDCs into environmentally friendly compounds has been little explored. A wide diversity of estrogen-degrading microorganisms could be used to develop such technologies, which include bioremediation processes for EDCs that could be implemented in biological filters for the post-treatment of wastewater effluent. This review describes problems associated with EDCs, primarily estrogenic EDCs, including exposure as well as the present status of understanding and the effects of natural and synthetic hormones and estrogenic EDCs on living organisms. We also describe potential biotechnological strategies for EDC biodegradation, and suggest novel treatment approaches for minimizing the persistence of EDCs in the environment.

DNA as an environmental sensor: detection and identification of pesticide contaminants in water with fluorescent nucleobases

Environmental contaminants pose a substantial health risk in many areas of the world. One of these risks is contamination of water with toxic organic species, such as herbicides and insecticides. Here we describe the discovery and properties of a set of fluorescent chemosensors that respond to micromolar concentrations of a broad range of common organic pesticides. The chemosensors are short DNA-like oligomers with fluorophores replacing DNA bases that are assembled via a DNA synthesizer. We screened a library of 1296 tetrameric compounds on polystyrene microbeads, and identified a set of chemosensor sequences that respond strongly to a set of structurally varied pesticide analytes. We show that ten chemosensors on beads can be used to detect and identify 14 different common pesticides at 100 μM, using the pattern of fluorescence intensity and wavelength changes. Limits of detection for two analytes were as low as 2 μM. The chemosensors are shown to function successfully in a practical setting, correctly identifying unknown pesticide contaminants in water from Felt Lake, California. The results establish a simple, low cost strategy for sensing environmental spills of toxic organics.

Priority Substances and Emerging Organic Pollutants in Portuguese Aquatic Environment: A Review

Aquatic environments are among the most noteworthy ecosystems regarding chemical pollution due to the anthropogenic pressure. In 2000, the European Commission implemented the Water Framework Directive, with the aim of progressively reducing aquatic chemical pollution of the European Union countries. Therefore, the knowledge about the chemical and ecological status is imperative to determine the overall quality of water bodies. Concerning Portugal, some studies have demonstrated the presence of pollutants in the aquatic environment but an overall report is not available yet. The aim of this paper is to provide a comprehensive review about the occurrence of priority substances included in the Water Framework Directive and some classes of emerging organic pollutants that have been found in Portuguese aquatic environment. The most frequently studied compounds comprise industrial compounds, natural and synthetic estrogens, phytoestrogens, phytosterols, pesticides, pharmaceuticals and personal care products. Concentration of these pollutants ranged from few ng L(-1) to higher values such as 30 μg L(-1) for industrial compounds in surface waters and up to 106 μg L(-1) for the pharmaceutical ibuprofen in wastewaters. Compounds already banned in Europe such as atrazine, alkylphenols and alkylphenol polyethoxylates are still found in surface waters, nevertheless their origin is still poorly understood. Beyond the contamination of the Portuguese aquatic environment by priority substances and emerging organic pollutants, this review also highlights the need of more research on other classes of pollutants and emphasizes the importance of extending this research to other locations in Portugal, which have not been investigated yet.

Four-year advanced monitoring program of polar pesticides in groundwater of Catalonia (NE-Spain)

Pesticide contamination of groundwater is of paramount importance because it is the most sensitive and the largest body of freshwater in the European Union. In this paper, an isotopic dilution method based on on-line solid phase extraction-liquid chromatography (electrospray)-tandem mass spectrometry (SPE-LC(ESI)-MS/MS) was used for the analysis of 22 pesticides in groundwater. Results were evaluated from monitoring 112 wells and piezometers coming from 29 different aquifers located in 18 ground water bodies (GWBs), from Catalonia, Spain, for 4 years as part of the surveillance and operational monitoring programs conducted by the Catalan Water Agency. The analytical method developed allows the determination of the target pesticides (6 triazines, 4 phenylureas, 4 organophosphorous, 1 anilide, 2 chloroacetanilides, 1 thiocarbamate, and 4 acid herbicides) in groundwater with good sensitivity (limits of detection <5 ng/L), accuracy (relative recoveries between 85 and 116%, except for molinate), and repeatability (RSD<23%), and in a fully automated way. The most ubiquitous compounds were simazine, atrazine, desethylatrazine and diuron. Direct relation between frequency of detection of each target compound and Groundwater Ubiquity Score index (GUS index) is observed. Desethylatrazine and deisopropylatrazine, metabolites of atrazine and simazine, respectively, presented the highest mean concentrations. Compounds detected in less than 5% of the samples were cyanazine, molinate, fenitrothion and mecoprop. According to the Directive 2006/118/EC, 13 pesticides have individual values above the requested limits (desethylatrazine, atrazine and terbuthylazine lead the list) and 14 samples have total pesticide levels above 500 ng/L. The GWB with the highest levels of total pesticides is located in Lleida (NE-Spain), with 9 samples showing total pesticide levels above 500 ng/L. Several factors such as regulation of the use of pesticides, type of activities in the area, and irrigation were discussed in relation to the observed levels of pesticides.

Biodegradability enhancement of a pesticide-containing bio-treated wastewater using a solar photo-Fenton treatment step followed by a biological oxidation process

This work proposes an efficient combined treatment for the decontamination of a pesticide-containing wastewater resulting from phytopharmaceutical plastic containers washing, presenting a moderate organic load (COD=1662-1960 mg O₂ L⁻¹; DOC=513-696 mg C L⁻¹), with a high biodegradable organic carbon fraction (81%; BOD₅=1350-1600 mg O₂ L⁻¹) and a remaining recalcitrant organic carbon mainly due to pesticides. Nineteen pesticides were quantified by LC-MS/MS at concentrations between 0.02 and 45 mg L⁻¹ (14-19% of DOC). The decontamination strategy involved a sequential three-step treatment: (a) biological oxidation process, leading to almost complete removal of the biodegradable organic carbon fraction; (b) solar photo-Fenton process using CPCs, enhancing the bio-treated wastewater biodegradability, mainly due to pesticides degradation into low-molecular-weight carboxylate anions; (c) and a final polishing step to remove the residual biodegradable organic carbon, using a biological oxidation process. Treatment performance was evaluated in terms of mineralization degree (DOC), pesticides content (LC-MS/MS), inorganic ions and low-molecular-weight carboxylate anions (IC) concentrations. The estimated phototreatment energy necessary to reach a biodegradable wastewater, considering pesticides and low-molecular-weight carboxylate anions concentrations, Zahn-Wellens test and BOD₅/COD ratio, was only 2.3 kJ(UV) L⁻¹ (45 min of photo-Fenton at a constant solar UV power of 30 W m⁻²), consuming 16 mM of H₂O₂, which pointed to 52% mineralization and an abatement higher than 86% for 18 pesticides. The biological oxidation/solar photo-Fenton/biological oxidation treatment system achieved pesticide removals below the respective detection limits and 79% mineralization, leading to a COD value lower than 150 mg O₂ L⁻¹, which is in agreement with Portuguese discharge limits regarding water bodies.

New indexes for compound prioritization and complexity quantification on environmental monitoring inventories

INTRODUCTION

Lists of compounds resulting from environmental monitoring may be conveniently represented in a very general way using Pareto distributions, after ranking them on descending order according to their concentration or hazard quotient expressed as percentages, depending on whether the objective of the monitoring is focussed on mass load occurrence or risk assessment respectively.

MATERIALS AND METHODS

Ranked distributions are characterized using appropriate indexes, such as h (Hirsch), well known in other disciplines like bibliometry. Furthermore, to such ordered distributions, simple numerical power type equations relating rank order and occurrence probability can be fitted, following the so-called power or Zipf law. Both h indices and the characteristic power law exponents are interpreted as measures of complexity of the overall mixture. On the other hand, compounds included within the h index may be seen as the most relevant in the mixture, thus providing a reasonable indication of what is worth analyzing. These concepts have been applied, as case study, to the characterization of the pharmaceutical compounds found in the input and output streams of wastewater treatment plants.

RESULTS AND DISCUSSION

Whereas both the concentration load and ecotoxicity of pharmaceuticals in WWTPs obviously decrease in the output of the treatment (influent > effluent, sludge), complexity quantified using the proposed indexes does not follow the same trend, being this behaviour common to the three plants examined.

CONCLUSION

The joint combination of h compounds of the three plants studied allowed optimizing the list of compounds to be analyzed, which must be considered the key ones for the scenario under study.

Current mass spectrometry strategies for the analysis of pesticides and their metabolites in food and water matrices

Analysis of pesticides and their metabolites in food and water matrices continues to be an active research area closely related to food safety and environmental issues. This review discusses the most widely applied mass spectrometric (MS) approaches to pesticide residues analysis over the last few years. The main techniques for sample preparation remain solvent extraction and solid-phase extraction. The QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) approach is being increasingly used for the development of multi-class pesticide residues methods in various sample matrices. MS detectors-triple quadrupole (QqQ), ion-trap (IT), quadrupole linear ion trap (QqLIT), time-of-flight (TOF), and quadrupole time-of-flight (QqTOF)-have been established as powerful analytical tools sharing a primary role in the detection/quantification and/or identification/confirmation of pesticides and their metabolites. Recent developments in analytical instrumentation have enabled coupling of ultra-performance liquid chromatography (UPLC) and fast gas chromatography (GC) with MS detectors, and faster analysis for a greater number of pesticides. The newly developed "ambient-ionization" MS techniques (e.g., desorption electrospray ionization, DESI, and direct analysis in real time, DART) hyphenated with high-resolution MS platforms without liquid chromatography separation, and sometimes with minimum pre-treatment, have shown potential for pesticide residue screening. The recently introduced Orbitrap mass spectrometers can provide high resolving power and mass accuracy, to tackle complex analytical problems involved in pesticide residue analysis.