Bob Du

The rapid detection of pesticides residues in wheat has become a top food security priority. A solvent free headspace solid-phase microextraction (HS-SPME) has been evaluated for rapid screening of Organophosphorus pesticides (OPPs) residues in wheat with high sensitivity. The wheat sample (35 g) was placed in a 100 mL sealed amber glass vial and heated at 60°C for 45 min. The 8 OPP residues were extracted with a 50 μm/ 30μm DVB/CAR/PDMS fiber. In the HS-SPME procedures, the fiber was exposed in the headspace above sample for 45 min extraction, and then removed from the HS and injected in the GC injection port at 250°C for desorption of extracted chemicals. The multi residues were determined with a GC flame photometric detector GC-FPD and qualified by a GC mass spectrometer detector (GC-MSD). Seven fortification levels of 8 organophosphorus pesticides on wheat were analyzed. The GC responses for 50μm/30μm DVB/CAR/PDMS fiber were increased with increasing the fortification levels and there were significant (r2 > 0.985) linear regressions. The Lowest of Detections (LODs) of the multi pesticide standards were evaluated under the conditions of the validation study in a range of levels from 0 (control) to 100 ng (pesticides residue) g-1 of wheat that separated on a low-polar GC capillary column (Agilent DB-35UI). The result of HS-SPME method was compared with QuEChERS AOAC 2007.3 method.