Rapid Screening of Multiple Pesticide Residues in Lycii Fructus and Raw Juice Samples Using an Automated Sample Cleanup Platform Combined with GC-Q-TOF/MS.

Abstract

Background: Lycii Fructus and its raw juice are widely consumed but may be contaminated with pesticide residues, posing health risks. Traditional methods for pesticide residue detection are often labor-intensive and time-consuming.

Objective: This study aims to develop a rapid, automated method for screening pesticide residues in Lycii Fructus and its raw juice using a combination of micro solid-phase extraction (μ-SPE) and gas chromatography-quadrupole-time-of-flight mass spectrometry (GC-Q-TOF/MS).

Methods: An automated sample cleanup platform (PAL-RTC, Precision Automated Liquid Handler-Robotic Tool Change) was integrated with μ-SPE technology for sample preparation. Matrix-matched external standards were used for quantification, and method validation was conducted to compare μ-SPE with dispersive solid-phase extraction (d-SPE). Performance parameters including linearity, LOQ, recovery rates, and RSDs were evaluated.

Results: In total, 84.5% of the pesticides showed strong linearity (R2 > 0.99) over the concentration range 2-1000 μg/L. The LOQ for 91.4% of pesticides was below 20 μg/kg, with recovery rates between 70 and 120% and RSD ≤20%. Screening detection limits (SDLs) were between 1 and 20 μg/kg, with 96.8% of pesticides having an SDL below 5 μg/kg. The μ-SPE method demonstrated superior reproducibility at the low spiking level (10 μg/kg), detecting 415 pesticides, compared to 369 for d-SPE. Analysis of 100 Lycii Fructus and 50 raw juice samples revealed the presence of 24 pesticides, including 3 restricted types.

Conclusions: The μ-SPE method, integrated with PAL-RTC and GC-Q-TOF/MS, offers a more efficient and accurate approach for detecting pesticide residues in Lycii Fructus and its raw juice compared to traditional methods, reducing labor and improving reproducibility.

Highlights: Compared to the d-SPE method, the μ-SPE method integrated with PAL-RTC demonstrated better reproducibility and stability at low spiking levels, significantly enhancing the efficiency of sample cleanup.