Harmonized Quality Assurance/Quality Control Provisions for Nontargeted Measurement of Urinary Pesticide Biomarkers in the HBM4EU Multisite SPECIMEn Study.

A set of quality assurance/quality control (QA/QC) criteria for nontargeted measurement of pesticide exposure markers in a large-scale study of human urine has been proposed and applied across five laboratories within the HBM4EU project. Quality control material, including reference standards and fortified pooled urine samples (QC urine) were prepared in a centralized way and distributed across participants to monitor analytical performance and consistency of the liquid chromatography coupled to high-resolution mass spectrometry data generated with a harmonized workflow. Signal intensities, mass accuracy, and retention times of selected QA/QC markers covering a broad range of physicochemical properties were monitored across QC solvent standards, QC urine samples, study urine samples, and procedural blanks, setting acceptance thresholds for repeatability and accuracy. Overall, results showed high repeatability of the collected data. The RSDs of the signal intensities were typically below 20-30% in QC and study samples, with good stability of the chromatographic separation (retention time drift within 2-4 s intrabatch and 5 s interbatch) and excellent mass accuracy (average error < 2 ppm). The use of the proposed criteria allowed for the identification of handling errors, instrumental issues, and potential batch effects. This is the first elaboration of harmonized QA/QC criteria applied across multiple laboratories to assess the quality of data generated by nontargeted analysis of human samples.

Pesticide residues in Nepalese vegetables and potential health risks.

We conducted this study in order to assess the pesticide residues in vegetables and examine the related human health risk. Therefore, residues of 23 pesticides (organophosphates, organochlorines, acaricides, fungicides, and insecticides of biological origin) were analysed in the three main vegetable crops grown in Southern Nepal: 27 eggplant, 27 chilli and 32 tomato samples representing (i) conventional (N = 67) and ii) integrated pest management (IPM) fields (N = 19). Pesticide residues were found in 93% of the eggplant samples and in all of the chilli and tomato samples. Multiple residues were observed in 56% of the eggplant samples, 96% of chilli samples and all of the tomato samples. The range (µg/kg) of total detected pesticide residues in eggplants, chillies and tomatoes was 1.71-231, 4.97-507, 13.1-3465, respectively. The most frequently detected pesticides in these vegetables were carbendazim and chloropyrifos. Pesticide residues in 4% of the eggplant, 44% of the tomato and 19% of the chilli samples exceeded the EU maximum residue limits (MRLs). The residues of triazophos, omethoate, chloropyrifos and carbendazim exceeded the EU MRLs. Compared to chilli and eggplant crops, more carbendazim was sprayed onto tomato crops (p < 0.05). We assessed adolescent and adult dietary exposure using hazard quotient (HQ) and hazard index (HI) equations for the identified pesticides. HQ> 1 was observed for chloropyrifos, triazophos and carbendazim in eggplants; profenofos, triazophos, dimethoate, omethoate, chloropyrifos and carbendazim in tomatoes; and dichlorvos and chloropyrifos in chillies. Of all of the HQs, the highest acute HQ (aHQ) was for triazophos (tomato) in adolescents (aHQ=657) and adults (aHQ=677), showing the highest risks of dietary exposure. The cumulative dietary exposure showed a higher HI for organophosphates (HI>83) and a lower HI for organochlorines, acaricides and biological insecticides (HI<1). The concentration of pesticide residues in the vegetable crops from the IPM field was considerably lower, suggesting a greater ability of IPM systems to reduce the dietary risks from exposure to pesticides.

Application of Fragment Ion Information as Further Evidence in Probabilistic Compound Screening Using Bayesian Statistics and Machine Learning: A Leap Toward Automation.

In this work, we introduce an automated, efficient, and elegant model to combine all pieces of evidence (e.g., expected retention times, peak shapes, isotope distributions, fragment-to-parent ratio) obtained from liquid chromatography-tandem mass spectrometry (LC-MS/MS/MS) data for screening purposes. Combining all these pieces of evidence requires a careful assessment of the uncertainties in the analytical system as well as all possible outcomes. To-date, the majority of the existing algorithms are highly dependent on user input parameters. Additionally, the screening process is tackled as a deterministic problem. In this work we present a Bayesian framework to deal with the combination of all these pieces of evidence. Contrary to conventional algorithms, the information is treated in a probabilistic way, and a final probability assessment of the presence/absence of a compound feature is computed. Additionally, all the necessary parameters except the chromatographic band broadening for the method are learned from the data in training and learning phase of the algorithm, avoiding the introduction of a large number of user-defined parameters. The proposed method was validated with a large data set and has shown improved sensitivity and specificity in comparison to a threshold-based commercial software package.

Rapid detection of pesticides not amenable to multi-residue methods by flow injection-tandem mass spectrometry.

Flow injection combined with tandem mass spectrometry (MS/MS) was investigated for the rapid detection of highly polar pesticides that are not amenable to multi-residue methods because they do not partition into organic solvents and require dedicated chromatographic conditions. The pesticides included in this study were amitrole, chlormequat, cyromazine, daminozide, diquat, ethephon, fosetyl-Al, glufosinate, glyphosate and its metabolite aminomethylphosphonic acid, maleic hydrazide, mepiquat and paraquat. The composition of the flow-injection solvent was optimized to achieve maximum MS/MS sensitivity. Instrumental limits of detection varied between <0.05 and 1 pg. Fruit, vegetable, cereal, milk and kidney samples were extracted with water (1% formic acid in case of paraquat/diquat) and ten times diluted in either methanol/0.1% formic acid, methanol/0.1% ammonia or acetonitrile/0.1% ammonia, depending on the pesticide. The ion suppression observed depended strongly on both the matrix and the pesticide. This could be largely compensated for by matrix-matched calibration, but more accurate quantification was obtained by using isotopically labelled standards (commercially available for most of the pesticides studied). The method detection limits ranged from 0.02 mg/kg for chlormequat and mepiquat to 2 mg/kg for maleic hydrazide and were 0.05-0.2 mg/kg for most other pesticide/matrix combinations. This was sufficiently low to test compliance with EU maximum residue limits for many relevant pesticide/commodity combinations. The method substantially reduces the liquid chromatography-MS/MS capacity demand which for many laboratories is prohibitive for inclusion of these pesticides in their monitoring and surveillance programmes.

Development and validation of a confirmative LC-MS/MS method for the determination of ß-exotoxin thuringiensin in plant protection products and selected greenhouse crops.

Bacterial products based on Bacillus thuringiensis are registered in many countries as plant protection products (PPPs) and are widely used as insecticides and nematocides. However, certain B. thuringiensis strains produce harmful toxins and are therefore not allowed to be used as PPPs. The serotype B. thuringiensis thuringiensis produces the beta-exotoxin thuringiensin (ßeT) which is considered to be toxic for almost all forms of life including humans (WHO 1999). The use of a non-registered PPP based on B. thuringiensis thuringiensis called bitoxybacillin was established through the determination of ßeT. First, an analytical reference standard of ßeT was characterized by nuclear magnetic resonance, liquid chromatography-high-resolution mass spectrometry and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Then, a confirmatory quantitative method for the determination of ßeT in PPPs and selected greenhouse crops based on LC-MS/MS was developed and validated. A limit of quantitation of 0.028 mg/kg was established, and average recoveries ranged from 85.6 % to 104.8 % with repeatability (RSDr) of 1.5-7.7 % and within-lab reproducibility (RSD(WLR)) of 17 %. The method was used for analysis of >100 samples. ßeT was found in leaves of ornamentals, but no evidence was found for use in edible crops.

External Quality Assurance Schemes (EQUASs) and Inter-laboratory Comparison Investigations (ICIs) for human biomonitoring of polycyclic aromatic hydrocarbon (PAH) biomarkers in urine as part of the quality assurance programme under HBM4EU.

Polycyclic aromatic hydrocarbons (PAHs) were included as priority substances for human biomonitoring (HBM) in the European Human Biomonitoring Initiative (HBM4EU), which intended to harmonise and advance HBM across Europe. For this project, a specific Quality Assurance and Quality Control (QA/QC) programme applying Inter-laboratory Comparison Investigations (ICIs) and External Quality Assurance Schemes (EQUASs) was developed to ensure the comparability and accuracy of participating analytical laboratories. This paper presents the results of four ICI/EQUAS rounds for the determination of 13 PAH metabolites in urine, i.e. 1-naphthol, 2-naphthol, 1,2-dihydroxynaphthalene, 2-, 3- and 9-hydroxyfluorene, 1-, 2-, 3-, 4- and 9-hydroxyphenanthrene, 1-hydroxypyrene and 3-hydroxybenzo(a)pyrene. However, 4 PAH metabolites could not be evaluated as the analytical capacity of participating laboratories was too low. Across all rounds and biomarkers, 86% of the participants achieved satisfactory results, although low limits of quantification were required to quantify the urinary metabolites at exposure levels of the general population. Using high-performance liquid or gas chromatography coupled with mass spectrometry (HPLC-MS; GC-MS) and isotope dilution for calibration as well as performing an enzymatic deconjugation step proved to be favourable for the accurate determination of PAHs in urine. Finally, the HBM4EU QA/QC programme identified an international network of laboratories providing comparable results in the analysis of urinary PAH biomarkers, although covering all parameters initially selected was still too challenging.

Qualitative aspects and validation of a screening method for pesticides in vegetables and fruits based on liquid chromatography coupled to full scan high resolution (Orbitrap) mass spectrometry.

The analytical capabilities of liquid chromatography with single-stage high-resolution mass spectrometry have been investigated with emphasis on qualitative aspects related to selective detection during screening and to identification. The study involved 21 different vegetable and fruit commodities, a screening database of 556 pesticides for evaluation of false positives, and a test set of 130 pesticides spiked to the commodities at 0.01, 0.05, and 0.20 mg/kg for evaluation of false negatives. The final method involved a QuEChERS-based sample preparation (without dSPE clean up) and full scan acquisition using alternating scan events without/with fragmentation, at a resolving power of 50,000. Analyte detection was based on extraction of the exact mass (±5 ppm) of the major adduct ion at the database retention time ±30 s and the presence of a second diagnostic ion. Various options for the additional ion were investigated and compared (other adduct ions, M + 1 or M + 2 isotopes, fragments). The two-ion approach for selective detection of the pesticides in the full scan data was compared with two alternative approaches based on response thresholds. Using the two-ion approach, the number of false positives out of 11,676 pesticide/commodity combinations targeted was 36 (0.3 %). The percentage of false negatives, assessed for 2,730 pesticide/commodity combinations, was 13 %, 3 %, and 1 % at the 0.01-, 0.05-, and 0.20-mg/kg level, respectively (slightly higher with fully automated detection). Following the SANCO/12495/2011 protocol for validation of screening methods, the screening detection limit was determined for 130 pesticides and found to be 0.01, 0.05, and ≥0.20 mg/kg for 86, 30, and 14 pesticides, respectively. For the detected pesticides in the spiked samples, the ability for unambiguous identification according to EU criteria was evaluated. A proposal for adaption of the criteria was made.

Development and independent laboratory validation of a simple method for the determination of paraquat and diquat in potato, cereals and pulses.

A new sensitive, fast and robust method for the determination of paraquat and diquat residues in potatoes, cereals and pulses is presented. Different extraction conditions (solvent, time and temperature) have been evaluated using barley grain, potatoes and dry lentils containing incurred residues of diquat and paraquat. The finalised procedure involves extraction with a mixture of methanol/water/hydrochloric acid at 80 °C and analysis by liquid chromatography-tandem mass spectrometry. Diquat D4 and Paraquat D6 internal standards were added to the test portions prior to extraction. A small-scale inter-laboratory validation of the developed method for diquat and paraquat using potato and barley samples was conducted by three laboratories. The precision and accuracy of the method were determined from recovery experiments (five replicates) at 0.01 and 0.1 mg kg(-1). The recoveries obtained (n = 180) were in the range of 92-120 % with associated relative standard deviation (RSD) between 1.4-10 % for all compound/commodity/spiking concentration combinations.

Interlaboratory Comparison Investigations (ICIs) and External Quality Assurance Schemes (EQUASs) for human biomonitoring of perfluoroalkyl substances (PFASs) in serum as part of the quality assurance programme under HBM4EU.

Perfluoroalkyl substances (PFASs) are of very high concern due to their persistence and accumulative behaviour as well as their manifold adverse health effects. Human biomonitoring (HBM) based on the determination of PFASs in serum samples is an adequate and established strategy for exposure and risk assessment of the population. The suspected health risks associated with exposure levels in the general population call for reliable HBM data verified by Quality Assurance and Quality Control (QA/QC) measures. PFASs were among the chemicals selected as priority substances in HBM4EU, a pan-European project to harmonize and advance HBM within 30 European countries. For this purpose, the analytical comparability and accuracy of PFASs-analysing laboratories was assessed in a QA/QC programme comprising Interlaboratory Comparison Investigations (ICIs) and External Quality Assurance Schemes (EQUASs). This paper presents the evaluation process and discusses the results of four ICI/EQUAS rounds for the determination of eight perfluoroalkyl carboxylic acids and four perfluoroalkyl sulfonic acids (PFBS, PFHxS, PFHpS, PFOS) in serum. All 21 participating laboratories achieved satisfactory results for at least six of these biomarkers, although low limits of quantification (of about 0.1 µg/L) were required to quantify serum PFAS levels at general population exposure levels. The mean relative standard deviation of the participants' results (study RSDR) significantly improved from 22 % to 13 % over all PFAS biomarkers in the course of the four rounds. This QA/QC programme succeeded in establishing a network of laboratories with high analytical comparability and accuracy for the analysis of PFASs across 12 European countries.

Quantitative assessment of multiple pesticides in silicone wristbands of children/guardian pairs living in agricultural areas in South Africa.

Little is known about personal and time-integrated exposure to past and current used pesticides in agricultural areas and within-family exposure similarities. We aimed to assess exposure to pesticides using silicone wristbands in child/guardian pairs living on farms and in villages within two agricultural areas in South Africa. Using silicone wristbands, we quantified 21 pesticides in child/guardian pairs in 38 households over six days in 2018. Levels (in ng/g wristband) of pesticides and their transformation products (12 current-use pesticides and nine organochlorine pesticides) were measured using GC-MS/MS. We assessed the correlation between pesticide levels and between household members using Spearman correlation coefficients (rs). Multivariable generalized least squares (GLS) models, using household id as intercept, were used to determine level of agreement between household members, exposure differences between children and guardians and exposure predictors (study area, household location [farm vs. village] and household pesticide use). We detected 16 pesticides with highest detection frequencies for deltamethrin (89%), chlorpyrifos (78%), boscalid (56%), cypermethrin (55%), and p,p'-DDT (48%). Most wristbands (92%) contained two or more pesticides (median seven (range one to 12)). Children had higher concentrations than guardians for four pesticides. Correlation between the pesticide levels were in most cases moderate (rs 0.30-0.68) and stronger in children than in guardians. Five pesticides showed moderate to strong correlation between household members, with the strongest correlation for boscalid (rs 0.84). Exposure differences between the two agricultural areas were observed for chlorpyrifos, diazinon, prothiofos, cypermethrin, boscalid, p,p'-DDT and p,p'-DDE and within areas for cypermethrin. We showed that for several pesticides children had higher exposure levels than guardians. The positive correlations observed for child/guardian pairs living in the same household suggest non-occupational shared exposure pathways in these communities.

Proficiency and Interlaboratory Variability in the Determination of Phthalate and DINCH Biomarkers in Human Urine: Results from the HBM4EU Project.

A quality assurance/quality control program was implemented in the framework of the EU project HBM4EU to assess and improve the comparability of biomarker analysis and to build a network of competent laboratories. Four rounds of proficiency tests were organized for 15 phthalate and two DINCH urinary biomarkers (0.2-138 ng/mL) over a period of 18 months, with the involvement of 28 laboratories. A substantial improvement in performance was observed after the first round in particular, and by the end of the program, an average satisfactory performance rate of 90% was achieved. The interlaboratory reproducibility as derived from the participants' results varied for the various biomarkers and rounds, with an average of 24% for the biomarkers of eight single-isomer phthalates (e.g., DnBP and DEHP) and 43% for the more challenging biomarkers of the mixed-isomer phthalates (DiNP, DiDP) and DINCH. When the reproducibility was based only on the laboratories that consistently achieved a satisfactory performance, this improved to 17% and 26%, respectively, clearly demonstrating the success of the QA/QC efforts. The program thus aided in building capacity and the establishment of a network of competent laboratories able to generate comparable and accurate HBM data for phthalate and DINCH biomarkers in 14 EU countries. In addition, global comparability was ensured by including external expert laboratories.

Validation of automated library-based qualitative screening of pesticides by comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry.

A method for automated detection and reporting of pesticides in plant materials based on comprehensive two-dimensional GC/time-of-flight MS with library-based detection by software has been developed and validated. Optimum settings for detection parameters such as spectral match threshold and first and second dimension retention time tolerances were assessed with respect to occurrence of false detects and false negatives. Next the method was validated following European Union guidelines established for qualitative screening of pesticides. The validation was largely done in retrospect by using data obtained for spiked samples (235 pesticides, various crops, 0.01-0.2 mg/kg) that had been analyzed previously with routine samples over a period of 18 months. At 0.01 mg/kg, the required 95% confidence level (<5% false negatives) was met for 83 compounds. This increased to 185 compounds at the 0.2 mg/kg level. For a number of pesticides, especially at low levels, it had to be concluded that at this stage the method was not fit-for-purpose to reliably demonstrate the absence of pesticides in samples to be analyzed. On the other hand, the fact that the overall detection rate at 0.01 mg/kg was 71% clearly showed that the method does provide added value for the numerous pesticides that are not covered by quantitative methods because the infrequent occurrence does not justify inclusion in such methods.

A human biomonitoring (HBM) Global Registry Framework: Further advancement of HBM research following the FAIR principles.

Data generated by the rapidly evolving human biomonitoring (HBM) programmes are providing invaluable opportunities to support and advance regulatory risk assessment and management of chemicals in occupational and environmental health domains. However, heterogeneity across studies, in terms of design, terminology, biomarker nomenclature, and data formats, limits our capacity to compare and integrate data sets retrospectively (reuse). Registration of HBM studies is common for clinical trials; however, the study designs and resulting data collections cannot be traced easily. We argue that an HBM Global Registry Framework (HBM GRF) could be the solution to several of challenges hampering the (re)use of HBM (meta)data. The aim is to develop a global, host-independent HBM registry framework based on the use of harmonised open-access protocol templates from designing, undertaking of an HBM study to the use and possible reuse of the resulting HBM (meta)data. This framework should apply FAIR (Findable, Accessible, Interoperable and Reusable) principles as a core data management strategy to enable the (re)use of HBM (meta)data to its full potential through the data value chain. Moreover, we believe that implementation of FAIR principles is a fundamental enabler for digital transformation within environmental health. The HBM GRF would encompass internationally harmonised and agreed open access templates for HBM study protocols, structured web-based functionalities to deposit, find, and access harmonised protocols of HBM studies. Registration of HBM studies using the HBM GRF is anticipated to increase FAIRness of the resulting (meta)data. It is also considered that harmonisation of existing data sets could be performed retrospectively. As a consequence, data wrangling activities to make data ready for analysis will be minimised. In addition, this framework would enable the HBM (inter)national community to trace new HBM studies already in the planning phase and their results once finalised. The HBM GRF could also serve as a platform enhancing communication between scientists, risk assessors, and risk managers/policy makers. The planned European Partnership for the Assessment of Risk from Chemicals (PARC) work along these lines, based on the experience obtained in previous joint European initiatives. Therefore, PARC could very well bring a first demonstration of first essential functionalities within the development of the HBM GRF.

Performance Evaluation of LC-MS Methods for Multimycotoxin Determination.

The co-occurrence of regulated mycotoxins in foods and feeds, together with modified ("masked") and emerging mycotoxins, has been increasingly reported worldwide in recent years. Therefore, sensitive, accurate, and validated methods for the simultaneous determination of these hazardous contaminants in different matrices are highly demanded to fulfil regulatory requirements and to carry out reliable surveillance programs. In these last years, LC-MS methodologies for multimycotoxin screening and/or quantification are being routinely used in control laboratories. However, to date, only one European Standard for multimycotoxin determination is based on LC-MS (EN 16877:2016). The need for standardized LC-MS methods for multimycotoxin determination has been highlighted by regulatory authorities and scientific advisory bodies, including the U.S. Food and Drug Administration and the European Commission. The European Committee for Standardization (CEN) has issued calls for tender for the development of standardized LC-MS methods for mycotoxins in food and animal feeding stuffs. As deliverables, some LC-MS based methods for multimycotoxin determination are currently under approval as European Standards. In addition, the European Commission has recently established specific criteria with which screening methods for mycotoxins, including LC-MS methods, have to comply for use for regulatory purposes. Validation procedures by single-laboratory and collaborative trials have been defined. This paper provides insights and advances on guidelines and tools for performance evaluation of LC-MS methods intended for quantitative determination and for semiquantitative screening of multimycotoxins. In particular, performance criteria set in the European Union and the United States are critically overviewed, and expectations, needs, and future challenges relevant to LC-MS methods for multimycotoxin determination are also discussed.

Pesticide residues in European agricultural soils - A hidden reality unfolded.

Pesticide use is a major foundation of the agricultural intensification observed over the last few decades. As a result, soil contamination by pesticide residues has become an issue of increasing concern due to some pesticides' high soil persistence and toxicity to non-target species. In this study, the distribution of 76 pesticide residues was evaluated in 317 agricultural topsoil samples from across the European Union. The soils were collected in 2015 and originated from 11 EU Member States and 6 main cropping systems. Over 80% of the tested soils contained pesticide residues (25% of samples had 1 residue, 58% of samples had mixtures of two or more residues), in a total of 166 different pesticide combinations. Glyphosate and its metabolite AMPA, DDTs (DDT and its metabolites) and the broad-spectrum fungicides boscalid, epoxiconazole and tebuconazole were the compounds most frequently found in soil samples and the compounds found at the highest concentrations. These compounds occasionally exceeded their predicted environmental concentrations in soil but were below the respective toxic endpoints for standard in-soil organisms. Maximum individual pesticide content assessed in a soil sample was 2.05 mg kg-1 while maximum total pesticide content was 2.87 mg kg-1. This study reveals that the presence of mixtures of pesticide residues in soils are the rule rather than the exception, indicating that environmental risk assessment procedures should be adapted accordingly to minimize related risks to soil life and beyond. This information can be used to implement monitoring programs for pesticide residues in soil and to trigger toxicity assessments of mixtures of pesticide residues on a wider range of soil species in order to perform more comprehensive and accurate risk assessments.

A health risk for consumers: the presence of adulterated food supplements in the Netherlands.

The use of food supplements is increasing. They are marketed as beneficial for health, well-being, physical or mental condition and performance, or to prevent diseases. Producers add synthetic compounds or illicit herbal material to food supplements to claim desired effects. Claims made to support marketing without scientific evidence are, however, illegal. Intake of adulterated food supplements may lead to serious adverse effects. The aim of this paper is to report the results of analyses of (adulterated) food supplements conducted by the Netherlands Food and Consumer Product Safety Authority between October 2013 and October 2018. In total, 416 supplements were analysed of which 264 (64%) contained one or more pharmacological active substances or plant toxins, such as caffeine, synephrine, sildenafil, icariin, sibutramine, higenamine, hordenine, phenethylamine, methylsynephrine, DMAA, phenolphthalein, octopamine and ephedrine. When compared to dose levels that are considered safe, daily doses of the substances in the food supplements were sometimes much higher, causing a risk for consumers who are unaware of the presence of these pharmacologically active substances. In many cases, neither food nor medicines legislation (easily) enables enforcement actions. This means that some products containing pharmacologically active substances (i.e. synthetic medicines and their illicit analogues), stay available on the market. An undesirable situation because for many of these substances no detailed toxicity data are available.

Dynamics of glyphosate and AMPA in the soil surface layer of glyphosate-resistant crop cultivations in the loess Pampas of Argentina.

This study investigates the dynamics of glyphosate and AMPA in the soil surface layer of two fields growing glyphosate-resistant crops in the loess Pampas of Córdoba Province, Argentina. Glyphosate decay and AMPA formation/decay were studied after a single application, using decay kinetic models. Furthermore, glyphosate and AMPA concentrations were investigated in runoff to evaluate their off-site risk. During a 2.5-month study, cultivations of glyphosate-resistant soybean and maize received an application of 1.0 and 0.81 kg a.e. ha-1, respectively, of Roundup UltraMax©. Topsoil samples (0-1, 1-2 cm) were collected weekly (including before application) and analysed for glyphosate, AMPA and soil moisture (SM) contents. Runoff was collected from runoff plots (3 m2) and weirs after 2 erosive rainfall events, and analysed for glyphosate and AMPA contents (water, eroded-sediment). Under both cultivations, background residues in soil before application were 0.27-0.42 mg kg-1 for glyphosate and 1.3-1.7 mg kg-1 for AMPA. In the soybean area, the single-first-order (SFO) model performed best for glyphosate decay. In the maize area, the bi-phasic Hockey-Stick (HS) model performed best for glyphosate decay, due to an abrupt change in SM regimes after high rainfall. Glyphosate half-life and DT90 were 6.0 and 19.8 days, respectively, in the soybean area, and 11.1 and 15.4 days, respectively, in the maize area. In the soybean area, 24% of the glyphosate was degraded to AMPA. In the maize area, it was only 5%. AMPA half-life and DT90 were 54.7 and 182 days, respectively, in the soybean area, and 71.0 and 236 days, respectively, in the maize area. Glyphosate and AMPA contents were 1.1-17.5 times higher in water-eroded sediment than in soil. We conclude that AMPA persists and may accumulate in soil, whereas both glyphosate and AMPA are prone to off-site transport with water erosion, representing a contamination risk for surface waters and adjacent fields.

Evaluation of Mycotoxin Screening Tests in a Verification Study Involving First Time Users.

(AFB1) in maize and wheat using LFD and LC-HRMS, respectively. The results of analyses were used to calculate intermediate precision (RSDip, covering the inter-analyst variability in preparing the analytical samples and the precision under repeatability conditions) cut-off values and false suspect rates. RSDip ranged from 6.5% to 30% for DON, and from 16% to 33% for AFB1. The highest obtained variances were associated with the AFB1 analyses due to working with much lower mass fractions. The rate of false suspect results were lower than 0.1% for all tested methods. All methods showed a fit-for-purpose method performance profile, which allowed a clear distinction of samples containing the analytes at the screening target concentration (STC) from negative control samples. Moreover, the first time users obtained method performances similar to those obtained for validation studies previously performed on the screening methods included in the training course.

Toward a generic extraction method for simultaneous determination of pesticides, mycotoxins, plant toxins, and veterinary drugs in feed and food matrixes.

A fast and straightforward generic procedure for the simultaneous extraction of various classes of pesticides, mycotoxins, plant toxins, and veterinary drugs in various matrixes has been developed, for subsequent analysis by liquid chromatography with mass spectrometric detection. As a first step, four existing multianalyte procedures and three newly proposed methods were compared for a test set of 172 pesticides, mycotoxins, and plant toxins spiked to a feed matrix. The new procedures, which basically involved extraction/dilution of the sample with water and an acidified organic solvent (methanol, acetonitrile, or acetone), were most promising. The three new generic extraction methods were further tested for applicability to other matrixes (maize, honey, milk, egg, meat). Overall, the best recoveries were obtained for acetone, followed by acetonitrile. With respect to matrix effects, acetonitrile was the most favorable solvent and methanol was the worst. The occurrence of matrix effects decreased for the matrixes in the order of feed > maize > meat > milk > egg > honey. The extraction method selected as the default procedure (water/acetonitrile/1% formic acid) was also evaluated for applicability to multiple classes of veterinary drugs in all six matrixes, with satisfactory results. Finally, the generic extraction procedure was validated for 136 pesticides, 36 natural toxins, and 86 veterinary drugs in compound feed and honey at three levels (0.01, 0.02, and 0.05 mg/kg) using ultraperformance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) for analysis of the extracts. For over 80% of the analytes, recoveries were between 70 and 120% and precision (expressed as relative standard deviation) was mostly in the range of 5-10% (except for feed at 0.01 mg/kg; adequate recoveries for 62% of the analytes). The limits of detection were from <0.01 to 0.05 mg/kg for most analytes, which is usually sufficient to verify compliance of products with legal tolerances. The results clearly demonstrate the feasibility of the generic approach proposed. Application of the method in routine monitoring programs would imply a drastic reduction of both effort and time.

Qualitative screening and quantitative determination of pesticides and contaminants in animal feed using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry.

A method has been developed for the target analysis of over 100 pesticides and contaminants in a complex feed matrix. The method is based on extraction with ethyl acetate, cleanup by gel permeation chromatography (GPC) and dispersive solid-phase extraction (SPE) with primary secondary amine phase (PSA), and analysis by comprehensive two-dimensional gas chromatography with full scan time-of-flight mass spectrometric detection (GC x GC-TOF-MS). Parameters studied during method development included a dispersive SPE cleanup step after GPC, large volume injection into the GC system and the GC x GC separation. Qualitative and quantitative performance of the GC x GC system was evaluated by analyzing spiked extracts in the range equivalent to 1-100 microg/kg in feed. At levels of 50 microg/kg and higher, all compounds targeted for could be identified fully automatically by the software based on their mass spectra. At lower levels the hit rate decreased with the concentration. System linearity was excellent in solvent and only slightly affected by matrix (correlation coefficients r>or=0.995 for 90% of the compounds). Limits of quantification were in the 1-20 microg/kg range for most compounds. The overall method was validated for 106 compounds at the 10 and 100 microg/kg level. Recoveries between 70% and 110% and RSDs below 20% were obtained for the majority of the compounds.