David Moreno-González

Screening of Over 600 Pesticides, Veterinary Drugs, Food-Packaging Contaminants, Mycotoxins, and Other Chemicals in Food by Ultra-High Performance Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometry (UHPLC-QTOFMS)

In this article, an accurate mass multiresidue screening method has been developed for the determination of over 630 multiclass food contaminants in different matrices using ultra-high performance liquid chromatography/(quadrupole)-time-of-flight mass spectrometry. The compounds included in the study were 426 pesticides, 117 veterinary drugs, 42 food-packaging contaminants, 21 mycotoxins, 10 perfluorinated compounds, 9 nitrosamines, and 5 sweeteners. The separation was carried out by liquid chromatography using a C18 column (50xa0mmxa0×xa02.1xa0mm, 1.8xa0μm particle size). The identification of the targeted species was accomplished using accurate masses of the targeted ions (protonated or deprotonated molecule) along with retention time data and characteristic fragment ion for reliable identification, using specific software for automated data mining and exploitation. The performance of the screening method was validated in terms of linearity, matrix effect, and limits of quantification for three representative food matrices (tomato, orange, and baby food) using a generic sample treatment based on liquid partitioning with acetonitrile (QuEChERS). The overall method performance was satisfactory with limits of quantification lower than 10xa0μgxa0kg −1 for the 44xa0% of studied compounds. In some cases (ca. 10–15xa0% of the pesticides depending on the matrix tested, maximum residue levels were not fulfilled). In orange, 15xa0% of the compounds displayed LOQs above the maximum residue levels (MRLs) set for the studied pesticides, which can be partially attributed to matrix effects. Moderate signal suppression was observed in the three matrices tested in most cases, being orange the matrix which produced the highest matrix effect and baby food the lowest one.

Evaluation of different cleanup sorbents for multiresidue pesticide analysis in fatty vegetable matrices by liquid chromatography tandem mass spectrometry

In this article we have evaluated the performance of different sorbents for the cleanup step in multiresidue pesticide analysis in fatty vegetable matrices using QuEChERS methodology. The three different matrices tested (olive oil, olives and avocado) were partitioned using acetonitrile prior to cleanup step. Afterwards, the supernatant was purified using different sorbents: C18+PSA (primary secondary amine), Z-Sep(+) (zirconium oxide and C18 dual bonded to silica), Z-Sep (zirconium oxide bonded to silica) and a novel sorbent Enhanced Matrix Removal-Lipid (EMR) whose composition has not been disclosed. The different cleanup strategies were compared for a group of 67 representative pesticides in terms of recovery rates, matrix effects, extract cleanliness and precision using ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). The best extraction efficiencies in olive oil matrix were obtained using EMR, while the results for olives and avocado were pretty similar amongst the different sorbents with an overall lower performance in terms of matrix effects and recovery rates compared to olive oil data, particularly in olives due to the higher complexity and concentration of coextracted species. On the other hand, the average reproducibility was clearly better when EMR sorbent was employed in all selected matrices for most pesticides (RSD<10% for 45, 52, and 56 pesticides in avocado, olives and olive oil respectively). The best results in terms of matrix effects were also obtained with EMR; with signal suppression lower than 20% for 79%, 16% and 51% of pesticides tested in olive oil, olives and avocado respectively. Using EMR as cleanup sorbent, limits of quantitation using UHPLC-MS/MS, ranged from 0.10 to 90μgkg(-1), allowing their determination at the low concentration levels demanded by current olive oil regulations in most cases.

Evaluation of nanoflow liquid chromatography high resolution mass spectrometry for pesticide residue analysis in food

This article reports on the evaluation of nanoflow liquid chromatography-mass spectrometry (LC-MS) for pesticide residue analysis in food. The approach is based on the use of reversed-phase C18nano columns with an integrated emitter, so that separation, ionization and detection are performed minimizing dead volumes. The use of nanoflow not only increases ionization efficiency and minimizes ionization suppression but also boost sensitivity compared to analytical-scale LC-MS methods. The nanoflow LC system was combined with full-scan high resolution mass spectrometry using a Q-Exactive Orbitrap instrument. The analytical performance was assessed for over 60 representative pesticides in five representative commodities (tomato, baby food, orange, fruit-based jam and olive oil). The sensitivity achieved with this configuration enables the implementation of high dilution factors (eg. 1:20, 1:50 or beyond) in pesticide residue workflows without compromising sensitivity, featuring limits of quantitation in the low ng kg-1 range. Using this dilution factors, signal suppression was found negligible in most cases (<10% in most cases, especially with 1:50 dilution), so that matrix-matched standards may be skipped, thus simplifying laboratory workflows. The robustness of the nanoflow LC system and its capability to withstand long analytical runs was also evaluated. Appropriate precision in terms of peak area and retention time was obtained at different concentration levels for over 125 injections without any instrument servicing. The main benefits of the nanoflow liquid chromatography approach are the high sensitivity gain and the outstanding reduction in matrix effects thanks to the high sample dilution factors that can be implemented, along with the substantial reduction in solvent usage.

Detection of over 100 selenium metabolites in selenized yeast by liquid chromatography electrospray time-of-flight mass spectrometry

The characterization of the selenometabolome of Selenized(Se)-yeast, that is the fraction of water soluble low-molecular weight Se-metabolites produced in Se-yeast is of paramount interest to expand the knowledge on the composition of this food supplement. In this work, we have applied liquid chromatography electrospray time-of-flight mass spectrometry (LC-TOFMS) to search for Se-species from the low molecular weight range fraction of the selenized yeast used for food supplements. Prior to LC-TOFMS, sample treatment consisted of ultrasound assisted water extraction followed by size exclusion fractionation assisted with off-line inductively coupled plasma mass spectrometry detection of isotope 82Se. The fraction corresponding to low-molecular weight species was subjected to LC-TOFMS using electrospray ionization in the positive ion mode. The detection of the suspected selenized species has been based on the information obtained from accurate mass measurements of both the protonated molecules and fragments from in-source CID fragmentation; along with the characteristic isotope pattern exhibited by the presence of Se. The approach enables the detection of 103 selenized species, most of them not previously reported, in the range from ca. 300-650Da. Besides the detection of selenium species, related sulphur derivate metabolites were detected based on the accurate mass shift due to the substitution of sulphur and selenium.

Multi-residue pesticide analysis in virgin olive oil by nanoflow liquid chromatography high resolution mass spectrometry

In this article, a nanoflow liquid chromatography system coupled to high resolution mass spectrometry (nanoflow LC/ESI Q-Orbitrap-MS) has been applied for the development of a multiresidue pesticide method for the determination of 162 multiclass pesticides in olive oil samples. Due to the relatively high lipid content of the raw QuEChERS acetonitrile extracts obtained from this type of fatty vegetable samples, a dispersive solid phase extraction (dSPE) sorbent proposed to retain both fatty acids and triglycerides, namely Enhanced Matrix Removal-Lipid (EMR-Lipid) has been implemented as additional cleanup step. The analytical performances of the proposed method were evaluated,achieving recoveries in the range 75-119% with relative standard deviations lower than 19% (nu202f=u202f6). The dSPE sorbent allowed the removal of most coextracted interferences without a significant loss of analytes. Matrix effects were also evaluated, showing a negligible effect for most of the compounds tested, when a dilution factor of 50 was applied. Notably, despite the use of relatively high dilution factors (e.g. 1:50) to minimize matrix effects, the lowest concentration levels detected with this method - in the low μgu202fkg-1 range - are well below the corresponding maximum residue levels established by the current European legislation.

Experimental and theoretical determination of pesticide processing factors to model their behavior during virgin olive oil production

The purpose of the present work was the experimental evaluation of pesticides transfer to virgin olive oil during the production step and prediction of their processing factors, which could be eventually used for the calculation of maximum residue limits (MRLs) in olive oil from the MRLs set in olives. A laboratory-scale Abencor system was used for the production of olive oil from olives spiked with the 104 pesticides studied, three different chromatographic methods being used for the analysis of raw olives and the obtained olive oil: (i) gas chromatography-tandem mass spectrometry (GC-MS/MS) for GC-amenable pesticides; (ii) hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) for polar pesticides, and; (iii) reversed-phase liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) for low to medium polarity pesticides. Processing factors experimentally calculated were correlated to their octanol-water partitioning coefficient (logKow), enabling the calculation of the equivalent MRLs in olive oil from the MRLs in olives, considering the percentage of oil extracted (oil yield) and the log Kow of each pesticide.

Matrix-effect free quantitative liquid chromatography mass spectrometry analysis in complex matrices using nanoflow liquid chromatography with integrated emitter tip and high dilution factors

Matrix effects are probably the Achilles heel of most quantitative liquid chromatography mass spectrometry (LC-MS) methods based on electrospray ionization. This work reports the evaluation of matrix effects in challenging matrices such as food extracts, human urine or wastewater at different dilution factors using nanoflow liquid chromatography-high resolution mass spectrometry (LC-MS). For this purpose, a suite of representative low-molecular weight compounds such as pesticides, drugs of abuse, sport drugs or environmental contaminants were selected. The approach is based on the use of reversed-phase C18 nano columns furnished with an integrated emitter tip. The nanoflow LC system was combined with full-scan high resolution mass spectrometry using a HRMS (orbitrap) instrument operated at a resolution of 70000. The sensitivity achieved with this configuration enables the implementation of high dilution factors (e.g. 1:20, 1:50 or beyond). When combining nanoflow LC-MS analysis with such high dilution factors (e.g. 1:50), signal suppression was negligible in most cases, so that matrix-matched standards may eventually be skipped, simplifying laboratory workflows by using external calibration in demanding applications such as drug analysis in urine, environmental contaminants in wastewater or pesticide testing in food, thus, eliminating the need for standard addition, matrix-matched calibration or isotopically-labelled standards.

Monitoring the degradation of atropine and scopolamine in soil after spiking with naturally contaminated organic millet

The spread of Datura sp. in European countries influences crop management and implies continuous food safety issues because of tropane alkaloids, atropine and scopolamine, the most relevant natural toxic compounds of this weed. These alkaloids can contaminate cereals to such a level that hampers food/feed related use and diverts batches of contaminated raw materials towards ultimate disposal such as burning. As no unambiguous information has been available on the fate of tropane alkaloids in soils, our study focused on the quantification and follow-up of these toxic residues in a soil experiment where the tropane alkaloids were mixed to the soil in the form of naturally contaminated unhulled millet in 1:40 millet:soil ratio - this approach provides a more realistic scenario compared to standard solution based spiking. To achieve accurate results, soil and millet extraction processes have been validated and a liquid chromatography - mass spectrometry set-up was addressed to provide selective and quantitative analysis. The initial concentration of atropine (75ngg-1) and scopolamine (47ngg-1) in the soil decreased with >90% in 15days and reached a high level of elimination (>97%) in 29days. This observation opens an option for the use of tropane contaminated millet or millet waste other than burning, as these toxic alkaloids can be significantly degraded in the soil system. On the other hand, the persistence of intact tropane alkaloids in soils might be questioned to the extent that calls the attention to the (re)assignment of their supposed allelopathic effects.

Matrix-effect free multi-residue analysis of veterinary drugs in food samples of animal origin by nanoflow liquid chromatography high resolution mass spectrometry

In this work, a sensitive method based on nanoflow liquid chromatography high-resolution mass spectrometry has been developed for the multiresidue determination of veterinary drugs residues in honey, veal muscle, egg and milk. Salting-out supported liquid extraction was employed as sample treatment for milk, veal muscle and egg, while a modified QuEChERS procedure was used in honey. The enhancement of sensitivity provided by the nanoflow LC system also allowed the implementation of high dilution factors as high as 100:1. For all matrices tested, matrix effects were negligible starting from a dilution factor of 100, enabling, thus, the use of external standard calibration instead of matrix-matched calibration of each sample, and the subsequent increase of laboratory throughput. At spiked levels as low as 0.1 or 1u202fµgu202fkg-1 before the 1:100 dilution, the obtained signals were still significantly higher than the instrumental limit of quantitation (S/N 10).

Dilute-and-shoot coupled to nanoflow liquid chromatography high resolution mass spectrometry for the determination of drugs of abuse and sport drugs in human urine

In this work, a sensitive nanoflow liquid chromatography high-resolution mass spectrometry screening method has been developed for the determination of multiclass drugs of abuse and sport drugs in human urine. 81 drugs belonging to different multiclass pharmaceuticals were targeted. The method is based on the use of a nanoLC column (75u202fµm × 150u202fmm, 3u202fµm particle size and 100u202fÅ pore) with the nanospray emitter tip integrated so that dead volumes are significantly minimized. Data acquisition method included both full-scan and all ion fragmentation experiments using an Orbitrap analyser (Q-Exactive) operated in the positive ionization mode. To increase laboratory throughput, a dilute-and-shoot methodology has been tested and proposed, based solely on direct urine dilution without further sample workup. Matrix effects were evaluated, showing a negligible effect for all studied compounds when a dilution 1:50 was implemented. Despite this high-dilution factor, limits of quantification were still satisfactory, with values below 5u202fµgu202fL-1 in most cases, being lower than their minimum required performance limits correspond established by the World Anti-Doping Agency. Therefore, the use of the dilute-and-shoot method with the enhanced sensitivity provided by nanoflow LC setup could be useful tool for the determination of studied compounds in drug testing, thus increasing laboratory performance, because a minimum sample treatment steps are required.