To be able to predict reversed phase liquid chromatographic (RPLC) retention times of contaminants is an asset in order to solve food contamination issues. The development of quantitative ...structure–retention relationship models (QSRR) requires selection of the best molecular descriptors and machine-learning algorithms. In the present work, two main approaches have been tested and compared, one based on an extensive literature review to select the best set of molecular descriptors (16), and a second with diverse strategies in order to select among 1545 molecular descriptors (MD), 16 MD. In both cases, a deep neural network (DNN) were optimized through a gridsearch.
Pesticides; QSRR; Molecular descriptors; Deep neural network; Reversed-phase liquid chromatography; Selection of inputs.
Predicting chromatographic retention times of pesticides has become more and more important for suspect and non-target screening. Indeed, high-resolution mass spectrometry hyphenated (HRMS) to liquid ...chromatography (LC) are of growing interest for research and monitoring of pesticides, their metabolites and transformation products. The development of quantitative structure-retention relationship models require selecting the most adequate and best set of molecular descriptors and the best machine-learning algorithm. Here, we used seven molecular descriptor sets extracted from four well-known studies and applied them to roughly 800 pesticides and their chromatographic reversed-phase retention times. We used and optimized five different machine-learning algorithms with these descriptor sets to carry out predictions. Our results show that a support-vector machine regression algorithm with only eight molecular descriptors gave the best compromise between the number of molecular descriptors, processing time and model complexity to optimize prediction performance for this specific gradient LC method.
•Development of a QSRR model for the prediction of pesticide retention times.•Comparison of seven molecular descriptor sets selected from a literature review.•Evaluation of various algorithms with descriptor sets to determine the best model.•A support-vector algorithm with eight descriptors was the most efficient model.
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•Residue behavior/processing factors of chlordecone assessed on four cooking processes.•ID-HPLC-MS/MS or LC-HRMS/MS used for target, suspect screening or untargeted approaches.•A ...significant decrease of CLD in bovine meat observed after microwave cooking process.•Traces of 5b-hydro-CLD and mono-hydro-CLD found in the uncooked liver.•No degradation by-product of CLD observed in the cooked liver.
Chlordecone (CLD) is a toxic organochlorine pesticide frequently used in the French West Indies until 1993, resulting in a contamination of soil and food. This study assessed the behaviour of CLD residues and CLD processing factors (PFs) during four home cooking processes: cooking in a conventional oven (“oven”), frying (“pan”), cooking in a microwave oven (“microwave”) and grilling (“grill”). These four processes were applied to six types of naturally contaminated beef (kidney, liver, rib, chuck, top-sirloin and sirloin). Targeted analyses with isotopic dilution were carried out by ID-HPLC-MS/MS to determine CLD concentrations before and after each cooking process and the corresponding processing factors. HPLC-HRMS/MS was used to find potential organochlorine degradation by-products and/or CLD metabolites present in samples by target, suspect and non-target screening. Cooking processes and especially microwave cooking led to a significant decrease in the CLD contained in beef (2% < PF < 17%). Traces of 5b-hydro-CLD and of another mono-hydro-CLD were found in the uncooked liver but no CLD degradation by-product was observed in the cooked liver.
•Prioritisation for testing 24 substances of the 1 478 in the EU Pesticide Database.•A five-step workflow based on European regulations and reports is proposed.•Detailed physicochemical properties ...for the selected substances are reported.•Future needs for thermal degradation studies are discussed.
This study aims at estimating which pesticide active substances (ASs) are the best candidates to study potential further degradation of the AS above 120°C. To achieve this, a prioritisation list was built following five consecutive criteria. This first includes substances that are anthropogenic, have a carbon backbone structure, are authorized in the European Union, and have a defined maximum residue limit (MRL). Then, substances were selected according to their physicochemical and structural properties, MRL in main food commodities, standard price and degradation in hydrolysis studies below 120°C. The results showed that out of the initial 1 478 substances reported in the European pesticide database, 24 ASs were selected as the best candidates to test the assumption of degradation above 120°C. This prioritisation list could be useful for future research studies to build their own list and save time in selecting suitable candidates according to their criteria.
Water and air quality of eight seawater swimming pools using chlorine disinfection was measured during four sampling campaigns, spread on one full-year, and in four thalassotherapy centers located in ...Southeast of France. Concentrations of trihalomethanes（THMs） in air and in water as well as concentrations of parameters, including nonpurgeable organic carbon（NPOC）, free residual chlorine（Cl_f）, pH, Kjeldhal Nitrogen（KN）, salinity,conductivity, bromide ions and, water and air temperature, were measured. Water and air samples were collected in triplicates morning — at the opening of the pools —, noon and night — at the closing of the pools —, in summer and winter. Data analysis was performed by Principal Component Analysis（PCA） and rotated component matrix, from both data quality and other parameters such as TOC, aromaticity（UV_（254））, pH, hygrometry, and free residual chlorine（Cl_f）. This statistical analysis demonstrates a high correlation between TOC, Cl_fand UV_（254） and THM levels found in air and water, particularly for the major ones（CHBr_3in water：300.0 μg/L mean, 1029.0 μg/L maximum; CHBr_3 in air： 266.1 μg/m~3 mean,1600.0 μg/m~3 maximum, and CHClBr_2 in water： 18.9 μg/L mean, 81.0 μg/L maximum;CHClBr_2 in air： 13.6 μg/m~3 mean, 150.0 μg/m~3maximum）. These high levels of bromoform（CHBr_3） are particularly worrisome in such health institutions, even these levels do not exceed the Permissible Exposure Limit（PEL） of 5 mg/m~3 as an 8 hour time-weighted average currently fixed by various administrations, such as Occupational Safety and Health Administration（OSHA）.
In forensic environmental investigations the main issue concerns the inference of the original source of the pollutant for determining the liable party. Isotope measurements in geochemistry, combined ...with complimentary techniques for contaminant identification, have contributed significantly to source determination at polluted sites. In this work we have determined the intramolecular 13C profiles of several molecules well-known as pollutants. By giving additional analytical parameters, position-specific isotope analysis performed by isotope ratio monitoring by 13C nuclear magnetic resonance (irm-13C NMR) spectrometry gives new information to help in answering the major question: what is the origin of the detected contaminant? We have shown that isotope profiling of the core of a molecule reveals both the raw materials and the process used in its manufacture. It also can reveal processes occurring between the contamination site ‘source’ and the sampling site. Thus, irm-13C NMR is shown to be a very good complement to compound-specific isotope analysis currently performed by mass spectrometry for assessing polluted sites involving substantial spills of pollutant.
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•Isotope ratio monitoring by 13C NMR for a unique intramolecular isotope composition.•Better inference of the pollution source by intramolecular 13C profiles.•Contribution to environmental forensic studies.
The high-resolution mass spectrometry is a powerful analytical tool for improving food safety and authenticity, but still underused in official control laboratories. The present work is a ...proof-of-concept study overviewing how liquid-chromatography coupled to high-resolution mass spectrometry could be used simultaneously for large-scale screening of contaminants and differentiation of honey samples. Within this study, the samples were extracted using all-in-one QuEChERS-based protocol that allowed for analysis of various anthropogenic contaminants and endogenous compounds. First, targeted-analysis of 52 honey samples led to unequivocal identification of 23 chemicals, including neonicotinoids, triazole fungicides and synergist. Then, suspect-screening using MSDial software allowed for tentative identification of 30 chemicals including plasticizers, flame-retardants and additives. Suspect-screening also made it possible to highlight tentative markers of chestnut honey (deoxyvasicinone, 2-quinolone, indoleacrylic acid and kynurenic acid) and citrus honey (caffeine, 2-oxindole and indole-3-carbinol). Lastly, non-targeted analysis enabled to separate honeys by their type, floral and geographical origins.
•Validation of HRMS method for the screening of 204 pesticides in baby foods.•Impact of detection criteria thresholds on false negatives and false positives rates.•Impact of a PIL and different MS/MS ...algorithms for identification.•Unequivocal identification of a pesticide in two samples using targeted screening.•A flame retardant TCEP identified in two samples using suspect-screening approach.
A screening method was developed for the multi-residue analysis of pesticides in baby foods using QuEChERS and UHPLC-Q-TOF. For sample preparation, the two-buffered versions of QuEChERS and different purification procedures were studied. False negatives and false positives were determined using different thresholds mentioned in the literature on the retention time and accurate mass measurement detection criteria. To reach unequivocal identification, the fragmentation spectra of the pesticides were used. The information-dependant-acquisition (IDA) mode was optimized with a precursor-inclusion list (PIL) to limit the loss of MS/MS data. Then, the experimental fragmentation spectra were compared to those included in a homemade library, by assessing different MS/MS algorithms and similarity scores. The optimised method was validated according to SANTE/11312/2021 guidelines. 95% and 73% of the pesticides presented a screening detection limit (SDL) and a limit of identification (LOI) ≤ 0.1 mg.kg−1. One plasticizer was found in the investigated samples by a suspect-screening approach.
The development of quantitative structure-retention relationship (QSRR) models has, until recently, required an adequate selection of molecular descriptors necessarily obtained based on a known ...chemical structure. However, these complex descriptors are not always available nor calculable when the high-resolution mass spectrometry (HRMS) annotation process is underway. Depending on the level of annotation, many structures or even various molecular formulas could be candidates. To secure and improve the annotation process and to save time, a QSRR model (using only 0D molecular descriptors) to predict retention times in reverse-phase liquid chromatography (RPLC) based on the molecular formula was developed, and a general QSRR annotation-based methodology was also proposed.
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•Development of QSRR model for the prediction of pesticide retention times.•QSRR model based only on molecular formula.•A methodology based on QSRR models to secure and improve annotation process.
•First screening of 694 contaminants in sweet products by UHPLC-Q/ToF.•A Taguchi orthogonal array was used to optimise the QuEChERS technique.•The validated method was used on 50 honey, jam, jelly ...and syrup samples.•It was found that 46% of the samples were positive to pesticide residues and/or TPs.•Concentrations of detected contaminants were estimated through semi-quantification.
A screening and semi-quantitative method was developed for the analysis of 694 various contaminants in honey, jam, jelly and syrup samples by ultrahigh-performance liquid chromatography and quadrupole time-of-flight mass spectrometry. Sample preparation, which was optimised using split factorial design, was based on acetate-buffered version of QuEChERS, followed by a clean-up step and a concentration step to enhance sensitivity of analytes. The method was validated according to SANTE/11312/2021 guidelines. The screening detection and limits of identification were established as being less than or equal to 0.05 mg.kg−1 for 89% and 74% of the contaminants, respectively. The validated screening method was applied to 50 concentrated sugary products. Overall, 46% of the samples were positive to pesticide residues. Most of the positive samples (78%) contained mixtures of pesticide residues. Three time-and-cost saving convenient strategies suitable for high-throughput analysis were proposed for the targeted semi-quantification of the previously contaminants identified in samples.
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