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During the last years, declines in honey bee colonies are being registered worldwide. Cholinergic pesticides and their extensive use have been correlated to the decline of pollinators and there is evidence that pesticides act as neuroendocrine disruptors affecting the metabolism of neuropeptides. However, there is a big absence of studies with quantitative results correlating the effect of pesticide exposure with changes on neuropeptides insects, and most of them are conducted under laboratory conditions, typically with individual active ingredients. In this study, we present an analytical workflow to evaluate pesticide effects on honey bees through the analysis of (neuro)peptides. The workflow consists of a rapid extraction method and liquid chromatography with triple quadrupole for preselected neuropeptides. For non-target analysis, high resolution mass spectrometry, multivariate analysis and automatic identification of discriminated peptides using a specific software and protein sequence databases. The analytical method was applied to the analysis of target and non-target (neuro)peptides in honey bees with low and high content of a wide range of pesticides to which have been exposed in field conditions. Our findings show that the identification frequency of target neuropeptides decreases significantly in honey bees with high concentration of pesticides (pesticide concentrations ≥ 500 μg kg −1 ) in comparison with the honey bees with low content of pesticides (pesticide concentrations ≤ 20 μg kg −1 ). Moreover, the principal component analysis in non-target search shows a clear distinction between peptide concentration in honey bees with high level of pesticides and honey bees with low level. The use of high resolution mass spectrometry has allowed the identification of 25 non-redundant peptides responsible for discrimination between the two groups, derived from 18 precursor proteins. [ABSTRACT FROM AUTHOR]

The present work is focused on evaluating the main operational parameters for multiresidue screening of an Orbitrap mass spectrometer for pesticide residue analysis in fruits and vegetables. Operational parameters such as resolution, software for the automatic detection, mass tolerance and retention time extraction window, along with the analytical performance, were evaluated in an updated UHPLC-Orbitrap-mass spectrometer working in full scan mode. The evaluation was performed using QuEChERS extracts of tomato, pepper, orange and green tea. The extracts were spiked with 170 selected pesticides at four concentration levels (10 μg/kg, 50 μg/kg, 100 μg/kg and 500 μg/kg). Extracts were diluted 5 fold before injection. Three different resolution settings (17,500, 35,000 and 70,000) were evaluated at various concentration levels. At 10 μg/kg, using a resolution of 17,500 and 5 ppm of mass tolerance, the detected pesticide rates were from 91% in tomato, to 83% in green tea. These percentages increased at higher resolution values. A resolution of 70,000 was adequate for such analysis even when a small percentage of false detect at low concentration was obtained. The rates of detected compounds increased and were from 98% in tomato to 88% in green tea. Mass tolerance of 5 ppm was the most adequate for screening purposes. The observed false negative detects were mainly a consequence of a lack of compound sensitivity exacerbated by ion suppression effects in the experimental conditions applied. With reporting limits of 10 μg/kg, reproducibility improved with resolution levels of 35,000 or higher. Linearity was investigated in the 2–100 ng/mL (equivalent to 10–500 μg/kg in the sample) range. Particularly good automatic screening effectiveness was obtained using the selected settings in the analysis of real samples where no false negatives detects and 5% of false positives detects were obtained. [ABSTRACT FROM AUTHOR]

Abstract: This work studied the elimination paths of the sulfonamide antibiotic sulfamethoxazole by ozonation in fast kinetic regime. The ozonation runs were performed in conditions favouring either the direct attack of the ozone molecule or the indirect attack by ozone-generated radical species with initial concentration of 0.150mM. When doses of ozone were transferred to the liquid phase 0.2mM, in no case did sulfamethoxazole remain in solution. Two main transformation pathways were found involving the preferential attack of molecular ozone or radical pathway and leading to the formation of six intermediates, which were identified by LC-ESI-QTOF-MS. Both routes took place simultaneously in the different conditions tested, leading to a hydroxylation reaction of the benzene ring, oxidation of the amino group on the benzene ring, oxidation of the methyl group and the double bond in the isoxazole ring and S–N bond cleavage. The most abundant reaction intermediate was that resulting from S–N bond cleavage. The toxicity of partially ozonated samples for Daphnia magna and Pseudokirchneriella subcapitata revealed the formation of toxic by-products during the early stages of reaction and the persistence of considerable toxicity after the total depletion of sulfamethoxazole. [Copyright &y& Elsevier]