Determination of Organochlorine Pesticides in Green Leafy Vegetable Samples via Fe₃O₄ Magnetic Nanoparticles Modified QuEChERS Integrated to Dispersive Liquid-Liquid Microextraction Coupled with Gas Chromatography-Mass Spectrometry

Figure 6

Typical GC-MS chromatograms of (a) blank matrix of spinach sample in SIM mode using the optimized QuEChERS procedure. (b) A standard spiked with 0.025 μg/mL of 8 OCPs in the blank matrix purification solution after QuEChERS. (c) A standard spiked with 0.025 μg/mL of 8 OCPs in the blank matrix purification solution after QuEChERS and then DLLME. (1) α-HCH, (2) β-HCH, (3) γ-HCH, (4) δ-HCH, (5) p,p′-DDE, (6) p,p′-DDD, (7) o,p′-DDT, and (8) p,p′-DDT.