Determination of Rhodamine B Pigment in Food Samples by Ionic Liquid Coated Magnetic Core/Shell Fe 3O 4@SiO 2 Nanoparticles Coupled with Fluorescence Spectrophotometry

The Ionic liquids (IL) 1-octyl-3-methylimidazole hexafluorophosphate ([OMIM]PF 6) was selected from three ILs along with (1-butyl-3-methylimidazole hexafluorophosphate ([BMIM]PF6), 1-hexyl-3-methyl-imidazole hexafluoro-phosphate ([HMIM]PF6), were coated by Fe 3O 4@SiO 2 nanoparticles with core-shell structure to prepare magnetic solid phase extraction agent (Fe 3O 4@SiO 2@IL) and establish a new method of magnetic solid phase extraction (MSPE) coupled with Fluorescence spectrophotometry for separation/analysis of Rhodamine B. The results showed that Rhodamine B was adsorbed rapidly byFe 3O 4@SiO 2@[OMIM]PF 6 and eluted by ethanol. Under the optimal conditions the linear range, detection limit (DL), correlation coefficient (R) and relative standard deviation (RSD) were found to be 0.40-140.00 ？g L -1, 0.06？g L -1, 0.9993 and 0.45% (n=3, c=10.00 μg L -1), respectively. The pre-concentration factor of the proposed method was 25-fold. The Fe 3O 4@SiO 2 NPs can be used repeatedly for 10 times. This method has been applied to the determination of Rhodamine B in food samples.