Utilization of a novel microwave-assisted homogeneous ionic liquid microextraction method for the determination of Sudan dyes in red wines.

A novel microwave-assisted homogeneous ionic liquid microextraction (MA-HILME) method was first developed for the extraction of Sudan dyes in red wines followed by detection using high-performance liquid chromatography. 1-dodecyl-3-methylimidazolium bromide ([C12MIM]Br) was used as extractant in a microwave-assisted extraction (MAE) procedure, and then transferred into hydrophobic solid-state ionic liquid after adding ammonium hexafluorophosphate ([NH4][PF6]). The separation between liquid state sample and solid state extractant can be realized easily. Several experimental parameters, including type and amount of extraction solvent, microwave power and irradiation time, amount of ion-exchange reagent ([NH4][PF6]), pH of sample solution, and ionic strength, were evaluated. Under the optimum experimental conditions, the linearity for the determining of the analytes was in the range of 0.5-100 μg L(-1), with the correlation coefficients ranging from 0.9995 to 0.9999. The limits of detection for Sudan I, Sudan II, Sudan III, and Sudan IV were 0.19, 0.18, 0.24, and 0.16 μg L(-1), respectively. When the present method was applied to the determination of Sudan dyes in red wines, satisfactory recoveries were obtained in the range of 78.5-106.8%, and relative standard deviations were lower than 9.7%.