Natural deep eutectic solvent-based extraction for isolating non-phthalate plastic additives from radish samples (Raphanus sativus L.)

Abstract

Non-phthalate plastic additives (NPPAs) are increasingly used as alternatives to phthalates in plastic manufacturing, but their presence in food crops and associated health risks remain largely underexplored. Thus, a natural deep eutectic solvent-based solid-liquid extraction (NADES-SLE) was developed for determining NPPAs in radish (Raphanus sativus L.) roots and leaves. Five NADES were synthetized and tested, and the hydrophobic combination of choline chloride and 2,3-butanediol (1:4 molar ratio) yielded the highest extraction efficiency. Its supramolecular structure was confirmed by nuclear magnetic resonance (NMR) spectroscopy, with nuclear Overhauser enhancement (NOE) effects. Key extraction parameters, NADES type and volume, extraction time, and agitation, were optimised. Seventeen NPPAs were identified and quantified using ultra-high performance liquid-chromatography coupled to quadrupole-Orbitrap mass spectrometry (UHPLC-Q-Orbitrap-MS). The method showed low quantification limits (6–300 μg/kg), recoveries between 70.0 and 119.1 %, and precision below 20.0 % at three concentration levels. Total NPPA concentrations ranged from 93.9 to 929.4 μg/kg in roots and from 51.4 to 515.6 μg/kg in leaves. Acetyl tributyl citrate (ATBC) and 1-hydroxycyclohexyl phenyl ketone (HCPK) were the most abundant compounds in roots and leaves, respectively. The analytical greenness metric for sample preparation (AGREEprep) metric scored the method at 0.52, outperforming conventional approaches (0.34–0.42) and confirming its greener profile. Estimated daily intake (EDI) were below tolerable daily intake (TDI) thresholds, indicating minimal dietary risk. This study highlights NADES-SLE as a sustainable and reliable approach for monitoring NPPAs in food crops and supports their safer use in plastic production.