title: Study of different HILIC, mixed-mode, and other aqueous normal-phase approaches for the liquid chromatography/mass spectrometry-based determination of challenging polar pesticides.
abstract: The aim of the study was to evaluate the performance of different chromatographic approaches for the liquid chromatography/mass spectrometry (LC-MS(/MS)) determination of 24 highly polar pesticides. The studied compounds, which are in most cases unsuitable for conventional LC-MS(/MS) multiresidue methods were tested with nine different chromatographic conditions, including two different hydrophilic interaction liquid chromatography (HILIC) columns, two zwitterionic-type mixed-mode columns, three normal-phase columns operated in HILIC-mode (bare silica and two silica-based chemically bonded columns (cyano and amino)), and two standard reversed-phase C18 columns. Different sets of chromatographic parameters in positive (for 17 analytes) and negative ionization modes (for nine analytes) were examined. In order to compare the different approaches, a semi-quantitative classification was proposed, calculated as the percentage of an empirical performance value, which consisted of three main features: (i) capacity factor (k) to characterize analyte separation from the void, (ii) relative response factor, and (iii) peak shape based on analytes' peak width. While no single method was able to provide appropriate detection of all the 24 studied species in a single run, the best suited approach for the compounds ionized in positive mode was based on a UHPLC HILIC column with 1.8 μm particle size, providing appropriate results for 22 out of the 24 species tested. In contrast, the detection of glyphosate and aminomethylphosphonic acid could only be achieved with a zwitterionic-type mixed-mode column, which proved to be suitable only for the pesticides detected in negative ion mode. Finally, the selected approach (UHPLC HILIC) was found to be useful for the determination of multiple pesticides in oranges using HILIC-ESI-MS/MS, with limits of quantitation in the low microgram per kilogram in most cases. Graphical Abstract HILIC improves separation of multiclass polar pesticides.
authors.affiliation: Analytical Chemistry Research Group, Department of Physical and Analytical Chemistry, University of Jaén, Campus Las Lagunillas, 23071, Jaén, Spain.|Department of Applied Chemistry, Faculty of Food Science, Szent István University, Villányi út 29-43, 1118, Budapest, Hungary.
authors.forename: Andrea
authors.initials: A
authors.lastname: Vass
authors.affiliation: Analytical Chemistry Research Group, Department of Physical and Analytical Chemistry, University of Jaén, Campus Las Lagunillas, 23071, Jaén, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Robles-Molina
authors.affiliation: Analytical Chemistry Research Group, Department of Physical and Analytical Chemistry, University of Jaén, Campus Las Lagunillas, 23071, Jaén, Spain.
authors.forename: Patricia
authors.initials: P
authors.lastname: Pérez-Ortega
authors.affiliation: Instituto de Investigación en Ciencias de la Alimentación, CIAL (CSIC-UAM), Nicolás Cabrera, 9, 28049, Madrid, Spain.
authors.forename: Bienvenida
authors.initials: B
authors.lastname: Gilbert-López
authors.affiliation: Department of Applied Chemistry, Faculty of Food Science, Szent István University, Villányi út 29-43, 1118, Budapest, Hungary.
authors.forename: Mihaly
authors.initials: M
authors.lastname: Dernovics
authors.affiliation: Analytical Chemistry Research Group, Department of Physical and Analytical Chemistry, University of Jaén, Campus Las Lagunillas, 23071, Jaén, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Molina-Díaz
authors.affiliation: Analytical Chemistry Research Group, Department of Physical and Analytical Chemistry, University of Jaén, Campus Las Lagunillas, 23071, Jaén, Spain. jfgreyes@ujaen.es.
authors.forename: Juan F
authors.initials: JF
authors.lastname: García-Reyes
mesh_terms: D002853:Chromatography, Liquid / Q000379:methods*; D005504:Food Analysis / Q000379:methods*; D005506:Food Contamination / Q000032:analysis*; D057927:Hydrophobic and Hydrophilic Interactions; D013058:Mass Spectrometry / Q000379:methods*; D010575:Pesticides / Q000032:analysis* / Q000737:chemistry*; D044367:Phase Transition; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014867:Water / Q000737:chemistry
chemical_list: D010575:Pesticides; D014867:Water
keywords: Food; HILIC; LC-MS; Mixed mode; Pesticide testing; Polar pesticides