Determination of ethylene oxide residues in processed food products by gas-liquid chromatography after derivatization.

A simple, sensitive and fast method (taking only 4-5 h) for the determination of residues of ethylene oxide (EO) and its reaction product, ethylene chlorohydrin (ECH), is described. For the analysis sodium hydroxide is added to the sample where ECH is transformed to EO. This is followed by the distillation of EO into dilute sulphuric acid containing sodium iodide, whereby EO is converted into ethylene iodohydrin (EIH). The EIH content is determined by gas chromatography using electron capture detection. The method has proved to be applicable to the analysis of low residue levels (less than 0.05 mg/kg, calculated as EO) in various foods, including processed foods. The collaborative studies carried out with four food products in six laboratories were remarkably successful with regard to repeatability of the method and reproducibility of the results. The recoveries of ECH were 50%-60%. In the 204 food products examined EO residues were found in 96 samples at concentration levels between 0.05 mg/kg and 1800 mg/kg.