Determination of glycyrrhizic acid as sweeteners by dual-wavelength overlapping resonance Rayleigh scattering

Abstract

This study used cationic dyes methyl violet (MV) and neutral red (NR) as probes, based on dual-wavelength overlapping resonance Rayleigh scattering (RRS), and designed two highly sensitive methods for the determination of the natural sweetener glycyrrhizic acid (GZA). In the Clark-Lubs buffer solution, when only MV or NR was present in the solution, they formed supramolecular polymers through hydrogen bonding. When adding GZA at different concentrations, the formation of ionic association complexes led to a subsequent decrease in RRS intensity at two wavelengths in the MV − GZA system and NR − GZA system, and the amount of the decline was proportional to the GZA concentration. The linear ranges were determined as 0.1 − 0.6 mg/L and 0.1 − 0.7 mg/L, with correlation coefficients of 0.9972 and 0.9996, and limits of detection were 0.052 mg/L and 0.016 mg/L, respectively. For this study, reaction conditions were optimized, potential interfering substances were investigated, and the mechanisms behind RRS generation and intensity decrease were discussed. The proposed methods were sensitive, fast, time-saving and efficient, and have been successfully applied to licorice and dried ginger decoction analysis, yielding satisfactory results.