Development of an Automated Column Solid-Phase Extraction Cleanup of QuEChERS Extracts, Using a Zirconia-Based Sorbent, for Pesticide Residue Analyses by LC-MS/MS

J Agric Food Chem. 2015 Jun 3;63(21):5107-19. doi: 10.1021/jf505539e. Epub 2015 Feb 23.


A new, automated, high-throughput, mini-column solid-phase extraction (c-SPE) cleanup method for QuEChERS extracts was developed, using a robotic X-Y-Z instrument autosampler, for analysis of pesticide residues in fruits and vegetables by LC-MS/MS. Removal of avocado matrix and recoveries of 263 pesticides and metabolites were studied, using various stationary phase mixtures, including zirconia-based sorbents, and elution with acetonitrile. These experiments allowed selection of a sorbent mixture consisting of zirconia, C18, and carbon-coated silica, that effectively retained avocado matrix but also retained 53 pesticides with <70% recoveries. Addition of MeOH to the elution solvent improved pesticide recoveries from zirconia, as did citrate ions in CEN QuEChERS extracts. Finally, formate buffer in acetonitrile/MeOH (1:1) was required to give >70% recoveries of all 263 pesticides. Analysis of avocado extracts by LC-Q-Orbitrap-MS showed that the method developed was removing >90% of di- and triacylglycerols. The method was validated for 269 pesticides (including homologues and metabolites) in avocado and citrus. Spike recoveries were within 70-120% and 20% RSD for 243 of these analytes in avocado and 254 in citrus, when calibrated against solvent-only standards, indicating effective matrix removal and minimal electrospray ionization suppression.

Keywords: ITSP; LC-MS/MS; QuEChERS; SPE; Z-Sep; avocado; citrus; multiresidue; pesticide; zirconia.

Publication types

  • Evaluation Study

MeSH terms

  • Adsorption
  • Chromatography, High Pressure Liquid
  • Citrus / chemistry*
  • Food Contamination / analysis*
  • Fruit / chemistry
  • Persea / chemistry*
  • Pesticide Residues / chemistry
  • Pesticide Residues / isolation & purification*
  • Solid Phase Extraction / instrumentation
  • Solid Phase Extraction / methods*
  • Tandem Mass Spectrometry
  • Zirconium / chemistry


  • Pesticide Residues
  • Zirconium
  • zirconium oxide