Sensitive high-performance thin-layer chromatography-acetylcholinesterase inhibition assay combined with S9 metabolization and high-resolution mass spectrometry for effect-directed analysis of food contact materials

Effect-directed assay detection can prioritize potentially neurotoxic compounds within the vast chemical space of complex mixtures. For previously unknown (unknown unknowns) and chemically unidentified substances, a sensitive effect-directed detection is required. Hence, high-performance thin-layer chromatography hyphenated with the planar acetylcholinesterase (AChE) inhibition assay, including metabolization via the S9 liver system, was investigated for screening of potentially neurotoxic trace-level migrants and extracts from white polyurethane-coated tin cans. Two AChE inhibitor zones were detected. Their presence was confirmed using two independent substrates, i.e., naphthyl acetate/Fast Blue B salt and indoxyl acetate. Detected AChE inhibitor zones were identified as phthalic acid oligomers and linear alkyl sulfonic acids by high-resolution mass spectrometry. Their presence was verified by co-analysis of purchased or synthesized reference candidates.