Abstract
The Ionic liquids (IL) 1-octyl-3-methylimidazole hexafluorophosphate ([OMIM]PF<sub>6</sub>) 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<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub> nanoparticles with core-shell structure to prepare magnetic solid phase extraction agent (Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>@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<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>@[OMIM]PF<sub>6</sub> 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<sup>-1</sup>, 0.06g L<sup>-1</sup>, 0.9993 and 0.45% (n=3, c=10.00 µg L<sup>-1</sup>), respectively. The pre-concentration factor of the proposed method was 25-fold. The Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub> NPs can be used repeatedly for 10 times. This method has been applied to the determination of Rhodamine B in food samples.
Highlights
Rhodamine B (RhB), a red pigment, is widely used as colorant in textiles, dyeing, paper and printing [1]
Various techniques have been developed for the determination of RhB to date, including ultraviolet spectrophotometry [7], fluorescence spectrophotometry [8], capillary chromatography [9], high-performance liquid chromatography (HPLC) [10]
Extraction At room temperature, the sample solution after treatment and the pH buffer were added into a tube, and distilled water was added to 40.0 mL. 0.1 g IL magnetic nanoparticles (MNPs) was added into the tube
Summary
Rhodamine B (RhB), a red pigment, is widely used as colorant in textiles, dyeing, paper and printing [1]. RhB is harmful if swallowed by human and animals, and causes irritation to the skin, eyes and respiratory tract "[2], [3], [4]", and has been considered and used as color additive in foodstuffs. Because of the low price and bright color of rhodamine B, some traders use it as a food additive illegally [5], harming the health of consumers [6]. Due to this, it was considered worthwhile to make efforts to develop a simple method for the determination of RhB in different samples. Direct determination with spectrophotometry is difficult owing to low concentration of RhB in natural samples. It is important to develop a new method for determination/separation procedure of RhB
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