A novel derivatization reagent CPIOTs to quantitatively determine the content of ursolic acid and oleanolic acid in loquat leaves

A novel fluorescent labeling reagent 4-(2-(9-ethyl-9H-carbazol-3-yl)-1H-phenanthro[9,10-d] imidazol-1-yl) butyl-4-methylbenzene sulfonate (CPIOTs) was designed, synthesized and applied in this study for the determination of triterpene acids using high-performance liquid chromatography with a fluorescence detector (HPLC-FLD). The derivatives of CPIOTs demonstrated exceptional stability and fluorescence properties, with maximum excitation and emission wavelengths at 311 nm and 398 nm, respectively. Calibration curves under optimized conditions displayed outstanding linear responses, as evidenced by correlation coefficients (R 2 ) exceeding0.9996. The detection and quantification limits were in the range of 0.098–0.160 ng/ml and 0.354–0.528 ng/ml, respectively. Therefore, CPIOTs proved to be a successful tool for detecting trace levels of oleanolic acid (OA) and ursolic acid (UA) in loquat leaves samples.