Novel generation of nano-structured supramolecular solvents based on an ionic liquid as a green solvent for microextraction of some synthetic food dyes

In the present research, a new supramolecular solvent (SUPRAS) made up of aggregations of C(12)minBr ionic liquid (IL) was introduced for the first time. The addition of sodium dodecyl sulfate (SDS) led to formation of emulsions, and complete phase separation was obtained by centrifugation. According to the results, we found that the ratio of surfactant/SDS was a critical factor for SUPRAS formation. This method, based on IL-SUPRAS microextraction (ME) followed by high performance liquid chromatography with ultraviolet detection (HPLC-UV), was used for rapid extraction and determination of three synthetic food dyes (ponceau 4R (E 124), carmoisine (E 122), and erythrosine (ERs)) as model analytes in gummy candy, candy, fizzy drinks, and jelly powder samples. The effective parameters in the microextraction (i.e. pH, centrifugation time and rate, THF volume, and extraction time) were investigated and optimized by a one-variable-at-a-time method. Under the optimized conditions, the preconcentration factors of 68, 73, and 86 were obtained for carmoisine, ponceau 4R, and erythrosine, respectively. The calibration curves were linear in the range of 0.2-500 mu g L-1 with a coefficient of determination (R-2) more than 0.9970 for all of the analytes. The limit of detection (S/N = 3) of 0.05-0.1 mu g L-1 and the relative standard deviations (RSDs%) were less than 6.5% based on three replicate measurements. Finally, the proposed method (IL-SUPRAS-ME) with good relative recoveries in the range of 85.5-108.0% was successfully used for the extraction of the three model analytes in different foodstuff samples.