Analysis of Pesticide Residues in Spinach Using Agilent Bond Elut QuEChERS AOAC Kits by GC/MS
This document details a method for extracting and cleaning up 18 GC-amenable pesticide residues from spinach using the Agilent Bond Elut QuEChERS AOAC kits. The procedure involves a buffered aqueous/acetonitrile extraction followed by dispersive solid phase extraction (SPE) cleanup. To address the loss of planar pesticides caused by graphitized carbon black (GCB), a modified method utilizing toluene addition was employed alongside the standard kit procedure.
The extracted samples were analyzed using an Agilent Gas Chromatograph coupled with an Agilent 5975C Mass Spectrometer operating in selective ion monitoring (SIM) mode. The study validated the method in terms of recovery and reproducibility, achieving limit of quantitation (LOQ) values of 10 ng/g for most pesticides and 50 ng/g for folpet, all well below maximum residue limits (MRLs).
| Target Pesticides | 18 GC-amenable multiple pesticide class residues |
|---|---|
| Matrix | Spinach |
| Extraction Method | QUEChERS AOAC sample preparation approach |
| Cleanup Method | dispersive solid phase extraction (dispersive SPE) |
| Analysis Instrument | Gas Chromatography/Mass Spectrometry (GC/MS) |
| Detection Mode | Selective Ion Monitoring (SIM) |
| Limit of Quantitation (LOQ) | 10 ng/g (most pesticides), 50 ng/g (folpet) |
| Spiked Levels for Recovery | 10, 50, and 200 ng/g |
| GC Oven Program Start | 70 °C |
A modified method with the addition of toluene was employed to address the significant loss of planar pesticides caused by graphitized carbon black (GCB).
The limit of quantitation (LOQ) for folpet is 50 ng/g in spinach.