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

Liquid chromatography-high-resolution mass spectrometry for pesticide residue analysis in fruit and vegetables: Screening and quantitative studies

As a result of the range and the variety of toxic and undesirable substances in food, which pose a potential hazard to human health, there is an ever-increasing demand for analytical methods that can reliably detect and quantify contaminants and residues in foods. This review presents the state-of-the-art technology used in the determination of trace residues and contaminants in food by liquid chromatography-mass spectrometry (LC-MS). LC-MS instruments utilize many different types of mass analyzer to improve selectivity and also confidence in assigning the identity of the contaminants detected and to offer different approaches to analysis. We discuss current analytical approaches together with the major benefits and the limitations of these technologies with respect to screening, quantification and identification of contaminants and residues in food.

Liquid chromatography-mass spectrometry for the determination of chemical contaminants in food

Robust, efficient, sensitive and cost-effective analytical methodologies need to be developed continuously to guarantee food safety, quality and traceability. The rapid development of metabolomics-based approaches using mass spectrometry (MS) has demonstrated their potential to face these challenges. This review presents a critical overview of the most recent applications of MS-based metabolomics approaches for food quality, safety and traceability assays, covering the most relevant works published from 2010 to 2013. We also provide information about the different steps needed to develop a MS-metabolomics approach (i.e. sample treatment, analytical platform, and data processing).

Metabolomics approaches based on mass spectrometry for food safety, quality and traceability

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.

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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.

For about 500 pesticides, the sensitivity of a benchtop high-resolution mass spectrometer using the Orbitrap for mass separation was compared to that of a widely used (low-resolution) tandem mass spectrometer. Both instruments were coupled to LC and used electrospray ionization. The selectivity of the Orbitrap in the full-scan acquisition mode without fragmentation was evaluated at a resolution of 100 000 full width at half maximum for all pesticides detectable with sufficient sensitivity. For this purpose, quasimolecular ions were extracted within 5 ppm windows from total ion chromatograms of two types of extracts of cucumber, lemon, wheat flour, raisin, and tea. In each of the obtained reconstructed ion chromatograms (individual chromatograms for 500 pesticides, each pesticide in 10 different extracts) the sum of signals not arising from the analyte was used to get a measure on selectivity. In addition, the target analyte list was checked for ions of similar mass. The influence of matrix on the ability to detect low concentrations of fortified pesticides was also studied, with the help of spiked extracts. This part of the survey tested whether analyte peaks were lost because of insufficient mass resolution or an early closing C-Trap (used to control the ion current into the Orbitrap). Finally, the stability of the ion ratio [M+H]+/[M+Na]+ was tested, which may be helpful to confirm the identity of an analyte.

Sebastian Bergelt

Papers

Suitability of an orbitrap mass spectrometer for the screening of pesticide residues in extracts of fruits and vegetables.