Abstract: A quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction procedure was presented andoptimized for the determination of sterigmatocystin in eggs by high performance liquid chromatography-mass spectrometry (HPLC-MS). The analyte was extracted from samples with aqueous acetonitrile solution, followed by salting out using anhydrous NaSO4, NaCl and CH3COONa,and then purification and concentration with C18 sorbent and anhydrous Na2SO4 before analysis. Optimization of experimental conditions for maximum extraction efficiency was carried out using Plackett-Burman design, one-factor-at-a-time method and response surface methodology. The matrix-matched external standard calibration was employed for quantification. Moreover, all positive sampleswere confirmed by immunoaffinity column chromatography. The results of validation showed that good linearity with a correlation coefficient (R2) > 0.999 6 was achieved within the range from 0.125 to 1 000 ng/mL. The limit of detection (LOD) and the limit of quantification (LOQ) for sterigmatocystin in eggs were 0.1 and 0.5 μg/kg, respectively. Satisfactory recovery (86.8%–90.4%) and inter-day reproducibility (RSD, 1.5%–6.2%) were obtained with blank egg matrices at three spiked levels. Finally, the established method was applied to analyze 45 real samples, 10 of which were positive at concentrations of 0.5 to 3 608 μg/kg.

Key words: egg, sterigmatocystin, QuEChERS extraction, response surface methodology, high performance liquid chromatography-mass spectrometry