Pyridine ionic liquid functionalized bimetallic MOF solid-phase extraction coupled with high performance liquid chromatography for separation/analysis sunset yellow

Abstract

An effective method based on the pyridine ionic liquid functionalized bimetallic MOF solid-phase extractant (Cu/Co-MOF@[PrPy][Br]) coupled with high performance liquid chromatography (HPLC) for the separation/analysis sunset yellow was established. Cu/Co-MOF@[PrPy][Br] was characterized by FTIR, XRD, SEM and TEM. Several important factors, such as pH, amount of extractant, extract time, and types of eluents were investigated in detail. Under the optimal conditions, linear range of the method was 0.05-40.00 μg mL^-1, the detection limit was 0.02 μg mL^-1, and the linear correlation was good (R ² = 0.9992). The analysis of sunset yellow in soda, effervescent tablet and jelly proved that the method was simple and effective.

Fig. 1. SEM and TEM images of Cu/Co-MOF and Cu/Co-MOF@[PrPy][Br].

Fig. 2. (a) FT-IR spectra of Cu/Co-MOF, [PrPy][Br] and Cu/Co-MOF@[PrPy][Br]; (b) XRD pattern of Cu/Co-MOF and Cu/Co-MOF@[PrPy][Br]; (c) zeta potential of Cu/Co-MOF@[PrPy][Br].

Fig. 3. Optimization of analysis conditions (1.0 μg mL⁻¹ sunset yellow solution). Effect of (a) type of extractant, (b) extractant dosage, (c) pH, (d) sample volume, (e) eluents, (f) eluent volume.

Fig. 4. HPLC chromatograms. (a) Sunset yellow standard solution; (b) extraction of real sample spiked with sunset yellow standard solution; (c) real sample after extraction; (d) real sample without extraction.

Fig. 5. (a) Pseudo-first-order and (b) pseudo-second-order adsorption kinetic model of sunset yellow; (c) Langmuir and (d) Freundlich adsorption isotherm of ZIF-8@MIM–MIM composite to sunset yellow.