Molecularly imprinted coated graphene oxide solid-phase extraction monolithic capillary column for selective extraction and sensitive determination of phloxine B in coffee bean

• A new GO-MISPE monolithic capillary column was prepared.
• The column showed ability of impurities removal and excellent selectivity.
• Phloxine B existed in real sample was enriched more than 90 times.
• The GO-MISPE column presented good recovery and high stability.
• The method was prospered to analyze phloxine B and LOD achieved 0.3 ng g−1.

A method was developed to sensitively determine phloxine B in coffee bean by molecularly imprinted polymers (MIPs) coated graphene oxide (GO) solid-phase extraction (GO-MISPE) coupled with high-performance liquid chromatography and laser-induced fluorescence detection (HPLC–LIF). The GO-MISPE capillary monolithic column was prepared by water-bath in situ polymerization, using GO as supporting material, phloxine B, methacrylic acid (MAA), and ethylene dimethacrylate (EDMA) as template, functional monomer, and cross-linker, respectively. The properties of the homemade GO-MISPE capillary monolithic column, including capacity and specificity, were investigated under optimized conditions. The GO-MIPs were characterized by scanning electron microscopy (SEM) and Fourier transform-infrared spectroscopy (FT-IR). The mean recoveries of phloxine B in coffee bean ranged from 89.5% to 91.4% and the intra-day and inter-day relative standard deviation (RSD) values all ranged from 3.6% to 4.7%. Good linearity was obtained over 0.001–2.0 μg mL−1 (r = 0.9995) with the detection limit (S/N = 3) of 0.075 ng mL−1. Under the selected conditions, enrichment factors of over 90-fold were obtained and extraction on the monolithic column effectively cleaned up the coffee bean matrix. The results demonstrated that the proposed GO-MISPE HPLC–LIF method can be applied to sensitively determine phloxine B in coffee bean.

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