Pesticides In Environmental Matrices Research Articles

Efficient adsorption of endocrine-disrupting pesticides from water with a reusable magnetic covalent organic framework

A magnetic covalent organic framework (COF) is applied for the first time as adsorbent for the extraction of endocrine-disrupting pesticides from water. High adsorption efficiencies were found for lipophilic chlorpyrifos and atrazine, with calculated maximum adsorption capacities of 270 mg g−1 and 54 mg g−1, respectively, outperforming reported adsorbents, such as activated carbon, graphene, or metal−organic frameworks. Polar diquat showed very poor adsorption efficiency, indicating that hydrophobic interactions play a role in the adsorption. Calculations revealed that the interactions between the COF and the pesticides are mainly based on van der Waals interactions. Finally, recycling experiments showed that both pesticides can be recovered with an efficiency of over 90% using acetonitrile as solvent, with merely minor losses in adsorption capacity after five consecutive cycles of adsorption/desorption. The present study promotes further exploration of the possible application of COFs for the extraction and pre-concentration of pesticides in environmental matrices.

The screening of organophosphorus, organochlorine and synthetic pyrethroid pesticides residues in beef fat by tandem solid-phase extraction technique

For regulatory monitoring of pesticides in environmental matrices, a multiresidue analysis through solid phase extraction (SPE) technique and using gas chromatographic determination of organochlorine(OC), organophosphorus(OP) and synthetic pyrethroid pesticides residues in beef fat was studied. The group of pesticides was added to dissolved beef fat (0.5 g) and blended with 8% de-activation florisil. The florisil/fat mixture was packed into disposable filtration columns. This column was tandem with an octadecyl SPE column and was eluted with acetonitrile. The pesticide residues were determined by gas chromatography with electron capture and flame photometric detectors. Three kinds (including OC, OP and synthetic pyrethroid) with a total of 71 pesticides (including their metabolites) were tested in this study. With the exception of isoxthion and flucythrinate with high recovery rates (122% ± 13% and 137% ± 31%, respectively), according to the correlation coefficients for the 71 extracted pesticide standard curves (ranging from 0.9915 ± 0.0176 to 0.9999 ± 0.0200, n = 5), average recovery rate (ranging from 68 ± 9% to 117 ± 11%, n = 25 for each insecticide), inter-assay variability (ranging from 3 ± 3% to 17 ± 12%, n = 25 for each insecticide), intra-assay variability(ranging from 3 to 19%, n = 5 for each insecticide) indicated that the methodology is acceptable for the extraction, determination, and screening of theses residues in beef fat. The detection limits for OCs, OPs and synthetic pyrethroid pesticides are 2-21 ng/g, 6-31 ng/g and 3-118 ng/g, respectively. Comparing with studies conducted by the National Analytical Reference Laboratory in Western Australia in the field of pesticide residue testing in beef fat, the results indicated that the present method could accurately measure commonly used pesticide chemicals.

Environmental Metabolic Footprinting (EMF) vs. half-life: a new and integrative proxy for the discrimination between control and pesticidesexposed sediments in order to further characterise pesticides' environmental impact.

Pesticides are regularly used for a variety of applications and are disseminated throughout the environment. These substances may have significant negative impacts. To date, the half-life, t1/2, was often used to study the fate of pesticides in environmental matrices (water, soil, sediment). However, this value gives limited information. First, it does not evaluate the formation of by-products, resulting in the need for additional experiments to be performed to evaluate biodegradation and biotransformation products. T1/2 also fails to consider the chemical's impact on biodiversity. Resilience time, a new and integrative proxy, was recently proposed as an alternative to t1/2, with the potential to evaluate all the post-application effects of the chemical on the environment. The 'Environmental Metabolic Footprinting' (EMF) approach, giving an idea of the resilience time, was used to evaluate the impact of botanicals on soil. The goal is to optimise the EMF to study the impact of a microbial insecticide, the Bacillus thuringiensis israelensis (Bti), on sediment. The difficulty of this work lies in the commercial solution of Bti that is really complex, and this complexity yields chromatograms that are extremely difficult to interpret; t1/2 cannot be used. No methodologies currently exist to monitor the impact of these compounds on the environment. We will test the EMF to determine if it is sensitive enough to tolerate such complex mixtures. A pure chemical insecticide, the α-cypermethrin, will be also studied. The article shows that the EMF is able to distinguish meta-metabolome differences between control and exposed (with Bti) sediments.

OPCW Proficiency Test: A Practical Approach Also for Interlaboratory Test on Detection and Identification of Pesticides in Environmental Matrices

An overview of general strategy, standard procedures, and critical points, which may be found during carrying out an OPCW Proficiency Test concerning detection and identification of scheduled compounds relevant to Chemical Weapon Convention, has been presented. The observations have been illustrated following the case of the Eight OPCW Designated Laboratories Proficiency Test, which was performed in the OPCW Laboratory in Rijswijk in November and December 2000. Various useful hints, comments, and practical observations concerning the case study have been included as well. The same methodology and procedures may be also applied for detection, identification, and environmental analyses of pesticides and biocides, especially organophosphorus compounds.

Time of flight mass spectrometry applied to the liquid chromatographic analysis of pesticides in water and food

Liquid chromatography coupled to mass spectrometry (LC-MS) is an excellent technique to determine trace levels of polar and thermolabile pesticides and their degradation products in complex matrices. LC-MS can be equipped with several mass analyzers, each of which provides unique features capable to identify, quantify, and resolve ambiguities by selecting appropriate ionization and acquisition parameters. We discuss in this review the use of LC coupled to (quadrupole) time-of-flight mass spectrometry (LC-(Q)ToF-MS) to determine the presence of target and non-target pesticides in water and food. This technique is characterized by operating at a resolving power of 10,000 or more. Therefore, it gives accurate masses for both parent and fragment ions and enables the measurement of the elemental formula of a compound achieving compound identification. In addition, the combination of quadrupole-ToF permits tandem mass spectrometry, provides more structural information, and enhances selectivity. The purpose of this article is to provide an overview on the state of art and applicability of liquid chromatography time-of-flight mass spectrometry (LC-ToF-MS), and liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF-MS) for the analysis of pesticides in environmental matrices and food. The performance of such techniques is depicted in terms of accurate mass measurement, fragmentation, and selectivity. The final section is devoted to describing the applicability of LC-(Q)ToF-MS to routine analysis of pesticides in food matrices, indicating those operational conditions and criteria used to screen, quantify, and identify target and "suspected" pesticides and their degradation products in water, fruits, and vegetables. The potential and future trends as well as limitations of LC-(Q)ToF-MS for pesticide monitoring are highlighted.

Quantitative LC-ESI-MS Analysis for Pesticides in a Complex Environmental Matrix Using External and Internal Standards

Quantitative liquid chromatography electrospray mass spectrometry (LC-MS) analysis for pesticides in a complex environmental matrix using external and internal standard calibration was investigated. Various approaches to introducing different internal standard compounds to address quantitative errors associated with signal suppression were also examined. The study involved the analysis of pesticides in wheat hay matrix samples using three kinds of internal standard compounds: deuterium labeled (D3), carbon-13 (singly labeled), and structural analogs (derivatives) of the target analytes. Introduction of the internal standard by volumetric addition and direct post-column infusion were also studied and compared. Isotopically labeled internal standards (i.e. D3- 13C-) were found to be effective in correcting quantitative errors associated with signal suppression. The application of singly labeled 13C compounds may result in nonlinear calibration due to mass interference with the target analyte species. The interference may be compensated by using quadratic curve-fitting or subtraction of the interfering component. Although ineffective as volumetric internal standards, structural analogs can be effective in compensating for signal suppression when introduced into the LC effluent by continuous post-column infusion. Furthermore, the post-column introduction method allows the application of a single internal standard compound for the quantification of each analyte in a multi-component mixture. The use of internal standards can be effectively incorporated into residue analysis development methods for pesticides in environmental matrices. High accuracy and reproducibility can be achieved while improving method efficiency by reducing the need for comprehensive sample clean-up.

Screening of organophosphorus pesticides in environmental matrices by various gas chromatographic techniques

Gas chromatography with nitrogen-phosphorus detection (GC-NPD) using three different capillary columns, DB-1701, RSL-300 and DB-5, was employed for the identification of 25 organophosphorus pesticides and various transformation products. Spectral information on and typical fragment ions of the different compounds were obtained by gas chromatography-mass spectrometry with electron impact and negative-ion chemical ionization. Clean-up methods involving Florisil, Empore C 18 extraction discs, C 18 cartridges and gel permeation chromatography using Bio-Beads S-X3 were evaluated for the isolation of selected organophosphorus pesticides from water and biota samples. Recoveries for water samples varied from 77 to 120% with a relative standard deviation of 2–8% whereas recoveries of 30–130% were obtained with biota samples. Applications are reported for the determination of pyridafenthion in water samples from the Ebro delta (Tarragona, Spain).