Analysis of veterinary drug and pesticide residues in animal feed by high-resolution mass spectrometry: comparison between time-of-flight and Orbitrap.

The use of medium-high-resolution mass spectrometers (M-HRMS) provides many advantages in multi-residue analysis. A comparison between two mass spectrometers, medium-resolution (MRMS) time-of-flight (TOF) and high-resolution (HRMS) Orbitrap, has been carried out for the analysis of toxic compounds in animal feed. More than 300 compounds belonging to several classes of veterinary drugs (VDs) and pesticides have been determined in different animal feed samples using a generic extraction method. The use of a clean-up procedure has been evaluated in both instruments, and several validation parameters have been established, such as the matrix effect, linearity, recovery and sensitivity. Finally, both instruments have been used during the analysis of 18 different feed samples (including chicken, hen, rabbit and horse). Some VDs (sulfadiazine, trimethoprim, robenidine and monensin sodium) and one pesticide (chlorpyrifos) have been identified. In general, better results were obtained using the Orbitrap, such as sensitivity (1-12.5 µg kg(-1)) and recovery values (60-125%). Moreover, this analyser had several software tools, which reduced the time for data processing and were easy to use, performing quick screening for more than 450 compounds in less than 5 min. However, some disadvantages such as the high cost and a decrease in the number of detected compounds at low concentrations must be taken into account.

Identification of transformation products of pesticides and veterinary drugs in food and related matrices: use of retrospective analysis.

Retrospective analysis has been applied in different samples, including honey, meat, feed and nutraceutical products from ginkgo biloba, soya, royal jelly and green tea, with the aim of searching transformation products of pesticides and veterinary drugs, which were not included in an initial analysis. Generic extraction and analytical procedures based on high resolution mass spectrometry (Exactive-Orbitrap analyser was used) have been applied. All obtained data have been reprocessed and some compounds as anhydroerythromycin in honey and 3,5,6-trichloro-2-pyridinol in feed have been detected, demonstrating the applicability and the utility of the procedure. Advantages and disadvantages of retrospective approach have been highlighted.

Analysis of pesticide and veterinary drug residues in baby food by liquid chromatography coupled to Orbitrap high resolution mass spectrometry.

Pesticide and veterinary drug residues have been simultaneously determined in several baby foods as meat, fish and vegetable-based baby food. A generic extraction method without clean-up step was applied. Moreover, the use of a representative matrix for proper quantification of all target compounds was studied and the best results were obtained when vegetable-based baby food was used as representative matrix, allowing the reliable quantification of more than 300 compounds. The method was validated and good recoveries were obtained for most of compounds at concentrations higher than 50 µg kg(-1). Limits of detection (LOD) ranged from 0.5 to 50 µg kg(-1), whereas limits of quantification (LOQ) were established between 10 and 100 µg kg(-1). Limits of identification (LOIs) ranged from 0.5 to 50 µg kg(-1). This method was applied to the analysis of 46 different baby food samples and no positive samples were found.

Evaluation of the potential of GC-APCI-MS for the analysis of pesticide residues in fatty matrices.

A method based on gas chromatography-atmospheric pressure chemical ionization-mass spectrometry (GC-APCI-MS) has been developed for the analysis of pesticides in meat by using quadrupole-time of flight mass spectrometry (QTOF-MS). Ionization and MS conditions were studied for 71 compounds, although only 51 showed acceptable performance. The protonated form of the analytes was mainly found ([M + H]⁺), although some compounds generated the molecular ion (M⁺(•)). A fast and generic extraction procedure was applied in sample pretreatment. The analytical method was suitable for qualitative analysis, and it was also evaluated for quantitative analysis, obtaining adequate recovery and precision values for most of the studied analytes at two concentration levels (50 and 150 µg/kg). Several operational drawbacks were found with this instrument, such as slow stabilization and moderate sensitivity, although the fast switching between LC and GC allows the increase of its applicability.

Wide-scope analysis of pesticide and veterinary drug residues in meat matrices by high resolution MS: detection and identification using Exactive-Orbitrap.

A multiresidue and multiclass method for the simultaneous determination of more than 350 compounds including pesticides, biopesticides and veterinary drugs in different meat matrices (beef, pork and chicken) by ultra-high performance liquid chromatography coupled to Orbitrap MS has been developed. In the present study, the determination of fragments was accomplished as an essential tool for a reliable identification of compounds using high resolution MS. To obtain these fragments, different strategies have been carried out in order to ensure an appropriate fragment assignment and identification. The analytical method is suitable for qualitative analysis, and it was also evaluated for quantitative analysis. Generic extraction conditions were optimized, obtaining adequate recovery and precision values for most of the studied analytes (>290). The limits of detection ranged from 2 to 16 µg kg(-1). Limits of quantification were 10 µg kg(-1) with the exception of few compounds with a higher value (50 or 100 µg kg(-1)). Limits of identification were also established, and they ranged from 2 to 150 µg kg(-1). This method was applied to the analysis of 18 meat samples and some veterinary drugs as enrofloxacin and sulfadiazine were detected and further identified/quantified (with triple quadrupole) in two different samples at 33 µg kg(-1) and trace levels, respectively. No pesticides were detected in the analyzed samples.

Analysis of veterinary drug residues in cheese by ultra-high-performance LC coupled to triple quadrupole MS/MS.

A simple, reliable, and fast multiresidue method has been developed for the determination of 17 veterinary drugs belonging to several families (macrolides, sulfonamides, and anthelmintics) in cheese at trace levels. Ultra-high-performance LC coupled to MS/MS has been used for the analysis of these compounds in less than 9 min. Veterinary drug residues have been extracted from cheese samples using a QuEChERS (quick, easy, cheap, effective, rugged, and safe)-based extraction procedure without applying any further clean-up step. Matrix-matched calibration was used for quantification and recoveries were calculated at three concentration levels (10, 50, and 100 µg/kg). The obtained values ranged from 70 to 110% for the selected compounds except for tylosin and josamycin at 100 µg/kg (111.7 and 112.7%, respectively). Intra- and interday precision were also evaluated and RSDs were lower than 25% in all the cases. LOQs ranged from 0.3 µg/kg (for thiabendazole, oxfendazole, mebendazole, josamycin, and fenbendazole) to 10.5 µg/kg (abamectin), whereas decision limit and detection capability ranged from 2.3 (thiabendazole) to 11.3 (abamectin) and 4.2 (thiabendazole) to 14.3 µg/kg (abamectin), respectively. Finally, 13 samples were analyzed and traces of thiabendazole were detected in two different cheeses.

Comprehensive qualitative and quantitative determination of pesticides and veterinary drugs in honey using liquid chromatography-Orbitrap high resolution mass spectrometry.

A database has been created for the simultaneous analysis of more than 350 pesticides and veterinary drugs (including antibiotics) using ultra-high performance liquid chromatography coupled to high resolution Orbitrap mass spectrometry (UHPLC-Orbitrap-MS). This is a comprehensive exact mass database built using the Exactive-Orbitrap analyzer. The developed database includes exact masses of the target ions and retention time data, and allows the automatic search of the included compounds. Generic chromatographic and MS conditions have been applied. The presented database is suitable for qualitative analysis, and it was also evaluated for quantitative purposes in routine analysis, after the optimization and validation of a generic extraction method in honey samples. Adequate recovery and precision values for most of the studied analytes were obtained and the limits of detection (LOD) ranged from 1 to 50 µg kg(-1). For pesticides, LODs were always lower than the MRLs established by European Union in honey, except for a few compounds. This method was applied to the analysis of 26 real honey samples and some pesticides (azoxystrobin, coumaphos, dimethoate and thiacloprid) were detected in 4 samples. Azoxystrobin and coumaphos were determined in two different samples (organic honey) at 1.5 µg kg(-1) and 5.1 µg kg(-1). Veterinary drugs were not detected in the analyzed samples.

Multi-mycotoxin analysis in eggs using a QuEChERS-based extraction procedure and ultra-high-pressure liquid chromatography coupled to triple quadrupole mass spectrometry.

A reliable and rapid method has been developed for the determination of 10 mycotoxins (beauvericin, enniatin A, A1, B1, citrinin, aflatoxin B1, B2, G1, G2 and ochratoxin A) in eggs at trace levels. Ultra-high-pressure liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) has been used for the analysis of these compounds in less than 7 min. Mycotoxins have been extracted from egg samples using a QuEChERS-based extraction procedure (Quick, Easy, Cheap, Effective, Rugged and Safe) without applying any further clean-up step. Extraction, chromatographic and detection conditions were optimised in order to increase sample throughput and sensitivity. Matrix-matched calibration was used for quantification. Blank samples were fortified at 10, 25, 50 and 100 µg kg(-1), and recoveries ranged from 70% to 110%, except for ochratoxin A and aflatoxin G1 at 10 µg kg(-1), and aflatoxin G2 at 50 µg kg(-1). Relative standard deviations were lower than 25% in all the cases. Limits of detection ranged from 0.5 µg kg(-1) (for aflatoxins B1, B2 and G1) to 5 µg kg(-1) (for enniatin A, citrinin and ochratoxin A) and limits of quantification ranged from 1 µg kg(-1) (for aflatoxins B1, B2 and G1) to 10 µg kg(-1) (for enniatin A, citrinin and ochratoxin A). Seven samples were analyzed and aflatoxins B1, B2, G1, G2, and beauvericin were detected at trace levels.