Ionic liquid-based matrix solid-phase dispersion coupled with homogeneous liquid–liquid microextraction of synthetic dyes in condiments

The ionic liquid-based matrix solid-phase dispersion homogeneous liquid–liquid microextraction (IL-based MSPD–HLLME) was developed and applied to the extraction of four banned dyes, including chrysoidin, safranine O, auramine O and rhodamine B, in condiment samples. High performance liquid chromatography was applied to the separation and determination of the analytes. The solid sample was directly treated by MSPD using ionic liquid as dispersant and the eluate obtained in MSPD was treated by HLLME. Some experimental parameters, including type of dispersant, ratio of sample to dispersant, type and volume of ionic liquid, type and volume of elution solvent, pH value and ionic strength of the elution solvent, amount of ion-pairing agent (NH4PF6) and extraction time, were investigated and optimized. The linearities for determining the analytes were in the range of 60–2000 μg kg−1 for chrysoidin, 40–2000 μg kg−1 for safranine O and 20–1000 μg kg−1 for auramine O and rhodamine B, with the correlation coefficients ranging from 0.9964 to 0.9991. The limits of detection for the analytes were between 6.7 and 26.8 μg kg−1 and the limits of quantification were between 15.99 and 58.48 μg kg−1. When the present method was applied to the analysis of spiked condiment samples, the recoveries of the analytes ranged from 90.69 to 113.52% and relative standard deviations were lower than 8.2%. The present method combined the advantages of MSPD and HLLME, and could be applied for the determination of synthetic dyes in condiment samples.