A rapid and efficient dispersive trehalose biosurfactant enhanced magnetic solid phase extraction for the sensitive determination of organophosphorus pesticides in cabbage (Brassica olearaceae var. capitate) samples by GC-FID

A simple, efficient and green method for extraction and enrichment of organophosphorus pesticides (OPPs) (sulfotep, diazinon, tolclofos-methyl, chlorpyrifos, isofenphos, and ethion) in cabbages was developed by dispersive biosurfactant microdroplets enhanced magnetic solid phase extraction. The approach is based on the addition of microdroplets of trehalose biosurfactant into the sample solution, which accelerates the mass transfer process between the extraction sorbent (phenyl-functionalized magnetic nanoparticles) and the aqueous solution. With the large contact surface area between both phases, the addition of this biosurfactant results in an increase in the extraction efficiency of OPPs in a short period of time. The final extraction conditions were type of desorption solvent, acetonitrile; extraction time, 60 s; mass of sorbent, 15 mg; amount of biosurfactant, 40 mg; type of disperser solvent, tetrahydrofuran; volume of disperser solvent, 500 μL; desorption time, 4 min; salt addition, 5% w/v; and sample volume, 30 mL. Under optimized microextraction and GC-FID conditions (using HP-5 MS column), the method has good linearity (0.5–500 μg kg–1) and good coefficients of determination (R2 ≥ 0.9953), low limits of detection (0.08–0.15 μg kg–1), high preconcentration factors (46–516), and satisfactory analyte recoveries (85.8–107.9 %) with relative standard deviations (RSDs) of <10 % (n=at least 3). This method was used to measure OPPs concentration levels in cabbages collected from several locations in Malaysia.