In-syringe cotton fiber solid-phase extraction coupled with stable-isotope-dilution liquid chromatography-tandem mass spectrometry for the determination of zearalenone

Here, an in-syringe cotton fiber solid-phase extraction (CF-SPE) method for the effective pretreatment of zearalenone (ZEA) in cereal crops and traditional Chinese medicines was developed. In this method, a syringe tube is packed with degreasing cotton, which serves as the normal-phase adsorbent for extracting ZEA from the nonpolar solvent extract of samples. The entire extraction process, including activation, sampling, washing, and elution steps, can be conveniently performed by employing a series of pull–push operations to force the solution to pass through the degreasing cotton. Optimal extraction recoveries were achieved using 200 mg of degreasing cotton as the adsorbent, a 3 mL volume of sampling solution, a desorption solution consisting of 2 mL of acetonitrile, and 4 pull–push times for both sampling and desorption. Coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS), quantification of ZEA in corns was achieved by validating matrix-matched calibration curves in the range of 0.1–100.0 ng/g with satisfactory linearity (R2 = 0.9996). The limit of detection (LOD) was calculated to be 0.025 ng/g with a signal-to-noise ratio (S/N) of 3. The intra-/inter-day relative recoveries and relative standard deviations were calculated to be in the ranges of 93.8%–110.4% and 3.2%–9.3%, respectively, which were satisfactory for quantitative analysis. The proposed in-syringe CF-SPE-LC-MS/MS method is simple, cheap, and labor/time-saving.