ABSTRACT
A simple high-performance liquid chromatography (HPLC) method for the simultaneous separation of the highly polar and weakly polar components of traditional Chinese medicines was developed via a strategic combination of isocratic and gradient elution methods. Liu-Shen-Wan and Liu-Wei-Di-Huang-Wan were used as representative examples of traditional Chinese medicines. This is the first time that 6 components of varying degrees of polarity in Liu-Shen-Wan had been successfully resolved in a single chromatographic run using an ultraviolet-visible detector with a fixed wavelength of 296 nm. In contrast to conventional gradient separation methods, this novel method offered a viable route for separation of the highly and weakly polar fractions simultaneously, thus greatly reducing the time and cost of analysis. This method therefore provides a more efficient way to determine the polar components present in traditional Chinese medicines. It would find potential application in drug screening, drug authentication, and product quality control.
ABSTRACT
A novel ionic liquid, 3-{[{4-[((carbamoyl)amino)ethyl methacrylate]butyl} ((carbamoyl)amino)ethyl methacrylate]propyl}-1-ethenyl-1H-imidazol-3-ium bromide (CCPEimBr) functionalized with vinyl, amino, and methacrylate groups, was synthesized and characterized with 1H NMR, FTIR, and HPLC-MS techniques. CCPEimBr was adopted as the functional monomer to prepare a molecularly imprinted polymerized ionic liquid hydrogel film on a glassy carbon electrode surface for human epididymis protein 4 (HE4) sensing. Gold nanoparticles (AuNPs) and ZnCdHgSe QDs were incorporated into the imprinted film as photo-electric active materials. The photocurrent response was measured to investigate the sensing performance of the imprinted sensors toward HE4. The imprinted photo-electrochemical sensor shows excellent selectivity, sensitivity, stability, and accuracy for HE4 determination. Experimental conditions including incubation time and pH value for determining HE4 were optimized in this study. The photocurrent variation (ΔI) decreased with increasing HE4 concentration (cHE4), and it was linearly proportional to cHE4 varied from 25 pg mL-1 to 4.0 ng mL-1. The detection limit of the imprinted sensor for determining HE4 was estimated to be 15.4 pg mL-1 (S/N = 3). The imprinted photo-electrochemical sensor was used to determine HE4 in human serum samples accurately.