HPLC using capillary monolithic column molecularly imprinted with composite metal organic frame for enrichment and detection of Ponceau 4R in Carthami flos

OBJECTIVE: To assess the performance of high-performance liquid chromatography (HPLC) combined with capillary monolithic column molecularly imprinted with metal organic frame (UiO-66-NH2@MIPs capillary monolithic column) for enrichment, purification and detection of Ponceau 4R in Carthami flos. METHODS: UiO-66-NH2@MIPs monolithic columns were prepared via in situ polymerization, and the adsorption properties and morphology of the columns were characterized by HPLC, scanning electron microscopy (SEM) and infrared (IR) spectral analysis. HPLC with the prepared columns was performed for detecting the content of Ponceau 4R in Carthami flos samples. RESULTS: The UiO-66-NH2@MIPs system showed a good linearity for detecting Ponceau 4R over the concentration range of 0.1-10.0 μg/mL with a correlation coefficient > 0.9999 and a detection limit (S/N=3) of 2.7×10-4 μg/mL. The mean recovery of Ponceau 4R in Carthami flos samples ranged from 82.60% to 105.56%, and the intra-day and inter-day relative standard deviation (RSD) values ranged from 2.4% to 3.4%. The recycling experiment showed that the system could be reused for sensitive detection of Ponceau 4R in Carthami flos. The capacity of UiO-66-NH2@MIPs column was 0.178 μg/mg, which was superior to that of other monolithic columns (0.089, 0.080, and 0.111 μg/ mg), demonstrating that the addition of UiO-66-NH2 increased the adsorption capacity of the system. Under the optimized conditions, the UiO-66-NH2@MIPs-HPLC system had an enrichment factor of over 73 folds with obviously reduced interference by the impurity peaks. CONCLUSIONS: The UiO-66-NH2@MIPs column-HPLC system has much better performance for enrichment, purification and detection of Ponceau 4R in Carthami flos than direct HPLC.