This application note describes the use of a quick, easy, cheap, effective, rugged, and safe (QuEChERS) EN sample preparation approach for extraction and cleanup of 13-pesticide residues representing various classes in spinach.
This document describes a method for extracting and cleaning up 13 pesticide residues from spinach using the Agilent Bond Elut QuEChERS EN sample preparation approach. The method utilizes a dispersive solid phase extraction (SPE) kit specifically designed for highly pigmented fruits and vegetables, which includes Graphitized Carbon Black (GCB) to remove pigments and sterols. The cleaned extracts are then analyzed using liquid chromatography coupled to electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) in positive ion multiple reaction monitoring (MRM) mode.
The study validates the performance of the Agilent EN Buffered Extraction kit and the Bond Elut QuEChERS EN Dispersive SPE kits for Highly Pigmented Fruits and Vegetables. Results indicate that the method achieves mean recoveries between 60% and 99% with a relative standard deviation (RSD) below 11%. The limit of quantitation (LOQ) for the target pesticides in spinach was found to be 5 ng/g, which is well below the maximum residue limits (MRLs).
| LOQ for pesticides in spinach | 5 ng/g |
|---|---|
| Mean recoveries | 60 to 99% |
| Average RSD | 5.5% |
| GCB amount in 2 mL tube | 7.5 mg |
| GCB amount in 15 mL tube | 45 mg |
| Centrifuge speed for sample prep | 4000 rpm |
| Micro-centrifuge speed for cleanup | 13,000 rpm |
The 2 mL tube contains 7.5 mg of GCB.
The LOQ for pesticides in spinach is 5 ng/g.
The mean recoveries range between 60 and 99%, with an average of 85.4%.