Rapid identification of high-viscosity rice soup quality using neutral desorption extractive electrospray ionization mass spectrometry†

High-viscosity rice soup is not only a popular food item but also a traditional Chinese medicinal remedy. Herein, we developed a high-throughput characterization platform for high-viscosity rice soup analysis using Neutral Desorption Extractive Electrospray Ionization Mass Spectrometry (ND-EESI-MS) with untargeted metabolomics. The chemical fingerprint of high-viscosity rice soup was directly analyzed by ND-EESI-MS, with exogenous (e.g., heavy metals and pesticides) and endogenous pollutants detected via qualitative and quantitative tandem mass spectrometry. Multivariate statistical analysis was then applied to distinguish the quality of the high-viscosity rice soup effectively. The concentrations of heavy metals and pesticide residues in high-viscosity rice soup were quantified, demonstrating a strong linear relationship (R² > 0.99) across the 0.05–2000.00 ng mL⁻¹ concentration range. The limits of detection (LOD) ranged from 0.27 ng mL⁻¹ to 2.18 ng mL⁻¹, while the limits of quantification (LOQ) ranged from 0.82 ng mL⁻¹ to 6.61 ng mL⁻¹. Furthermore, three specific compounds—3-methyl-2-butenoic acid, salicylic acid, and rhamnose—were quantified. These compounds demonstrated excellent linearity (R² > 0.99) within the linear range of 1.10–1500.00 ng mL⁻¹. The LOD ranged from 0.56 to 1.30 ng mL⁻¹, and the LOQ ranged from 1.71 to 3.95 ng mL⁻¹. Owing to its capability for simultaneous detection of exogenous and endogenous contaminants in complex viscous matrices, this ND-EESI-MS platform demonstrated significant potential to enhance quality control in food safety surveillance and pharmaceutical manufacturing.