Separation and determination of trace amounts of some plastic additives in dairy products

Abstract

Packing milk products in air-tight polyethylene containers is widely used for long-term storage. However, polyethylene will contain phenolic antioxidants which may tend to migrate into the milk. A TLC method has been developed to detect in the complex milk matrix traces of l,6-hexanediol-bis-3-(3,5-di-tert. butyl-4-hydroxyphenyl) propionate, pentaerythrityl-tetrakis[3-(3,5-di-tert. butyl-4-hydroxyphenyl) propionate] and 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert. butyl-4-hydroxyphenyl) benzene. By solvent extraction of the pretreated milk, the accidental additives together with the milk fat are separated from the aqueous phase. The extractant is evaporated and the residue dissolved in chloroform. Aliquots of this solution together with standard solutions are spotted on pretreated TLC or HPTLC plates. After development of the plates the phenolic substances are revealed by the Boute reaction. Quantitative measuremerits are obtained by using a TLC scanner at 405 nm. Orientative experiments on migration of one of the additives from HDPE into milk and other extractants have been performed and the results compared with those obtained from radioactive labelling techniques.