An article by Emmanouil Tsochatzis and colleagues from the Department of Food Science, Aarhus University, Denmark, and European Commission’s Joint Research Centre, Ispra, Italy, published on August 10, 2020, in the peer-reviewed Journal of Chromatography B, investigated the effect of salinity on specific migration from food contact materials (FCMs). The scientists developed a new sample preparation procedure, i.e., Salting-out Liquid-Liquid Extraction (SALLE), which allowed for a fast, sensitive and precise quantification of migration into water or the official food simulant A (10% v/v ethanol) for two substances: caprolactam (CAS 105-60-2), which is a monomer in polyamide plastics, and 2,4-di-tert-butyl phenol (2,4-DTBP, CAS 96-76-4), which, according to the authors, is a non-intentionally added substance (NIAS) in plastics. The new method is anticipated to be particularly useful for caprolactam, as this compound is “not easily extracted from aqueous solutions due to its hydrophilicity.”

The authors then investigated the influence of the presence of salt (up to 15%) on the migration of caprolactam and 2,4-DTBP from polyamide/polyethylene multilayer films used in food contact, specifically for packaging of fresh meat and sausages. The results showed that caprolactam migration was in all cases lower than its specific migration limit (SML, 15 mg/kg). Nonetheless, salinity was found to have “an important effect on the migration of caprolactam, with the presence of salt reducing its migration in case of water and increasing it in case of simulant A.” This was true only for the polar substance caprolactam, while migration of 2,4-DTBP, which is non-polar and hydrophobic, was not affected. Therefore, it was concluded that, specifically for polar substances, “the existence of [both] a fatty component and high salinity, could potentially accelerate the migration.”

Based on their findings, the scientists argue that their “preliminary results seem to indicate that migration testing should consider not only the well-known fatty content of a food, but also its salinity content, as it may end up affecting drastically the migration of polar substances.” This could mean that “a specifically designed food simulant to mimic food with high content of salt, currently inexistent, may be considered in the future.”


Tsochatzis, E., et al. (2020). “A Salting-out Liquid-Liquid extraction (SALLE) for the analysis of caprolactam and 2,4-di-tert butyl phenol in water and food simulants. Study of the salinity effect to specific migration from food contact materials.Journal of Chromatography B 1156: 122301.

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Andrew Turley (September 10, 2020). “Salty foods study casts doubt on effectiveness of regulatory FCM testing.” Chemical Watch