A comprehensive multiclass method for the determination of pesticide residues and selected mycotoxins in nuts using liquid chromatography with tandem mass spectrometry: Single Laboratory Validation

Highlights

• The simultaneous analysis of pesticide residues and mycotoxins in nuts is reported for the first time;
• The acetonitrile-based sample preparation provided satisfactory extraction;
• The two-step cleanup strategy effectively minimised the matrix effects;
• The performance of the method complied with the national (FSSAI) and international regulatory requirements and guidelines.

For the first time, a multiresidue analytical method is reported for the simultaneous analysis of multi-class pesticides and mycotoxins in nuts (groundnut, almond, cashew, and pistachio). The optimised sample preparation method involved comminution with water, extraction by acetonitrile, and cleanup using dispersive solid-phase extraction with a C₁₈ sorbent followed by a freezing step at - 80º C. The final analysis was carried out using liquid chromatography coupled with tandem mass spectrometry. The method performance was evaluated on 208 multi-class pesticides and mycotoxins [aflatoxins and ochratoxin A]. The strategies minimised the matrix effects and achieved suitable LOQs for checking regulatory compliance. The findings indicated satisfactory recoveries (70 - 110 %) at an LOQ of 0.01 mg/kg and higher levels with repeatability < 16 % RSD. Notably, the extraction and analysis using a single chromatographic run provided satisfactory selectivity, sensitivity, quantification, and accuracy (recovery and precision) for target compounds during single laboratory studies. The developed method complied with the regulatory requirements as well as international analytical quality control guidelines.