Natural deep eutectic solvent-based headspace gas chromatography for determination of 14 residual solvents in tea polyphenol products

Abstract

A headspace gas chromatography (HS-GC) method using a natural deep eutectic solvent (NADES) as a green matrix medium was reported for the simultaneous determination of 14 residual solvents in tea polyphenol products. Through systematic screening, a NADES, choline chloride–glycerol (1 : 2, mol mol⁻¹), was selected as the optimal matrix medium for tea polyphenol dissolution. After this, the headspace parameters, including equilibrium temperature and time were optimized. A HS-GC method was developed and demonstrated good linearity (R² = 0.9874–0.9995) over the 0.005–1000 µg g⁻¹ range. Limits of detection (LODs) and quantification (LOQs) ranged from 0.01 to 0.25 µg g⁻¹ and 0.03 to 0.83 µg g⁻¹, respectively. In spiked tea polyphenol samples, recoveries of 82.4% to 119.0% were obtained with relative standard deviations (RSDs) of 0.14–4.91%. And the above HS-GC method was utilized to measure 41 commercial tea polyphenol products. The results confirmed that the detected residual solvents in all the samples were below the Permissible Daily Exposure (PDE) limits. Risk assessment based on the hazard quotient (HQ, calculated as the ratio of daily intake to PDE) yielded values of 50.8% for benzene and 1.47% for dichloromethane. These results suggest that benzene requires prioritized control as a critical point. And we should also pay attention to dichloromethane. This study provides a green and efficient approach for residual solvent analysis in tea polyphenol products and demonstrates the potential of NADESs as sustainable matrix media in food safety testing.