Automated Multiplug Filtration Cleanup for Pesticide Residue Analyses in Kiwi Fruit (Actinidia chinensis) and Kiwi Juice by Gas Chromatography–Mass Spectrometry

To reduce labor-consuming manual operation workload in the cleanup steps, an automated multiplug filtration cleanup (m-PFC) method for QuEChERS (quick, easy, cheap, effective, rugged, and safe) extracts was developed. It could control the volume and speed of pulling and pushing cycles accurately. In this study, m-PFC was based on multiwalled carbon nanotubes (MWCNTs) mixed with primary-secondary amines (PSA) and anhydrous magnesium sulfate (MgSO4) in a packed column for analysis of pesticide residues followed by gas chromatography-mass spectrometry (GC-MS) detection. It was validated by analyzing 33 pesticides in kiwi fruit and kiwi juice matrices spiked at two concentration levels of 10 and 100 μg/kg. Salts, sorbents, m-PFC procedure, 4 mL of automated pulling and pushing volume, 6 mL/min automated pulling speed, and 8 mL/min pushing speed were optimized for each matrix. After optimization, spike recoveries were within 71-120% and <20% RSD for all analytes in kiwi fruit and kiwi juice. Matrix-matched calibrations were performed with the coefficients of determination >0.99 between concentration levels of 10 and 1000 μg/kg. The developed method was successfully applied to the determination of pesticide residues in market samples.