A method has been developed for the quantification of zearalenone (ZEN) in beer, using dispersive liquid-liquid microextraction (DLLME) followed by high performance liquid chromatography (HPLC). The optimisation of the method was performed using both high performance thin layer chromatography using a TLC-scanner and HPLC. Chloroform was used as the extraction solvent, and acetonitrile as the dispersive solvent. Under the optimum conditions, the enrichment factor for ZEN was 43.3 and the extraction recovery was 83%. Validation was performed for a working range of 0.4-120 pg mL À1 ZEN. The limit of detection was 0.12 pg mL À1 . The recoveries of the method for ZEN from beer samples at 10 and 20 pg mL À1 spiking levels were 71-108%. Different brewing styles of thirteen commercial beer samples were analysed, and ZEN was detected in 11 beer samples.

Abstract:In this work, an ultrasonic-assisted surfactant/ionic liquid aqueous two-phase system (ATPS) extraction method was developed to extract six tetracycline antibiotics from food samples before their chromatographic determination using high performance liquid chromatography. The ATPS was formed with 1-allyl-3-methyl-imidazolium bromide, Triton X-100, and dipotassium hydrogen phosphate. The parameters including type and amount of surfactant, ionic liquid and salt, pH of sample solution, and sonication time were optimized. Under the optimized conditions, linear calibration curves of the six tetracyclines were obtained in the range of 10-500 µ g L −1 with > r 2 = 0.990 (n = 9). The proposed green analytical extraction method was applied to the analysis of tetracycline antibiotics in milk and honey samples with recovery of 50%-110% and 68%-117%, respectively.