Effect-detection by planar SOS-Umu-C genotoxicity bioassay and chemical identification of genotoxins in packaging migrates, proven by microtiter plate assays SOS-Umu-C and Ames-MPF

Recently shown to meet regulatory requirements for safety assessment, high-performance thin-layer chroma-tography hyphenated with the SOS-Umu-C bioassay and S9 metabolization was applied to various food contact material prototypes, such as paper, plastic and coating samples. Studying reversed versus normal phase sepa-ration and piezoelectrical spraying versus syringe dosage of the bioassay, 14 genotoxic bands were detected. Three epoxides of linolenic acid were identified as genotoxic candidates in the paper migrate by heated elec-trospray and atmospheric pressure chemical ionization high-resolution mass spectrometry. These were confirmed by co-chromatography with linolenic acid epoxides. Comparatively poorer detection limits of in vitro microtiter plate bioassays and opposing effects/signal responses in the sample explained false-negative responses for paper migrate. However, the in vitro SOS-Umu-C microtiter plate bioassay confirmed the genotoxicity of a simulated linolenic acid epoxidation, and after sample concentration, the paper migrate mutagenicity was confirmed by the Ames-MPFTM bioassay.

Automated summary

High-performance thin-layer chromatography hyphenated with the SOS-Umu-C bioassay and S9 metabolization was used to assess the genotoxicity of various food contact materials. By studying different separation methods and dosage techniques, 14 genotoxic bands were detected, and three genotoxic candidates were identified in the paper migration. The in vitro SOS-Umu-C microtiter plate bioassay confirmed the genotoxicity of a simulated linolenic acid epoxidation, and the Ames-MPFTM bioassay confirmed the mutagenicity of the paper migration after concentration.