Facile preparation of nano-g-C_(3)N_(4)/UiO-66-NH_(2) composite as sorbent for high-efficient extraction and preconcentration of food colorants prior to HPLC analysis

In this work,the nano-g-C_(3)N_(4)/Ui O-66-NH_(2)composite was prepared by one-step solvothermal method.The as-prepared composite was characterized by scanning electron microscopy,Brunner-Emmet-Teller measurement,energy dispersive spectrometer,X-ray diffraction,and Fourier transform infrared spectroscopy.By using nano-g-C_(3)N_(4)/Ui O-66-NH_(2)composite as sorbent,a dispersive solid-phase extraction coupled with high-performance liquid chromatography was developed to sensitive analysis of food colorants including tartrazine,amaranth,carmine,sunset yellow,allura red and bright blue.The experiment parameters including the amount of sorbent,adsorption time,the p H of adsorption solution,desorption time,desorption solvent,the p H of desorption solution as well as the proportion between desorption solvent and buffer solvent were investigated.Under the optimized conditions,the limits of detection(S/N=3) and limits of quantitation (S/N=10) were determined in the ranges of 0.08-0.8 and 0.2-2.0 ng/m L,respectively.With the developed sample pretreatment method,carmine and brilliant blue were determined from blueberry juice by HPLC-DAD.The contents were calculated as 1.53μg/m L and0.17μg/mL,respectively.