Spectrofluorimetric determination of zearalenone using dispersive liquid-liquid microextraction coupled to micro-solid phase extraction onto magnetic nanoparticles

A new and sensitive method using dispersive liquid-liquid microextraction (DLLME) coupled to micro-solid phase extraction (mu-SPE) onto magnetic nanoparticles was developed for spectrofluorimetric determination of zearalenone (ZEN) in corn samples. In this study the solvent used to extract the analyte from a solid matrix, was then utilized as disperser solvent in the DLLME process. The DLLME was performed by injecting 3 mL of acetonitrile/water (8 : 2, v/v) (disperser) containing 320 mu L of 1-heptanol (extraction solvent) into 30 mL of water sample. In the present DLLME-mu-SPE approach, hydrophobic magnetic nanoparticles were used to retrieve the extractant of 1-heptanol in the DLLME step. In fact the target of mu-SPE was the 1-heptanol rather than the ZEN. The ZEN was extracted from hydrophobic magnetic nanoparticles by stirring with 1 mL of acetonitrile for 4 min. Influential parameters affecting the extraction efficiency were investigated and optimized. Under the optimum conditions the calibration curve for ZEN determination showed good linearity in the range 0.51-300.0 mu g L-1 (R-2 = 0.9994) and the limit of detection (S/N = 3) was estimated to be 0.25 mu g L-1. The intra-day and inter-day precision (RSD %) of ZEN were in the range of 2.7-4.1%. High recoveries ranging from 93.2 to 102.1% were obtained. The results demonstrated that the developed method is simple, inexpensive, accurate and remarkably free from interference effects. Also, this two-step method reclaimed the versatility of DLLME because the selection of the extraction solvent was not limited to the high density solvents.