Analysis of isophthalaldehyde in migration samples from polyethylene terephthalate packaging

In the present work, different pre-concentration strategies were evaluated for the analysis of isophthalaldehyde in migration samples from food packaging materials. This compound is a potential migrant in several copolymers used for food packaging, and since it is considered a non-intentionally added substance, its concentration in migration samples must be determined. Derivatisation was the first sample treatment evaluated. o-(2,3,4,5,6-Pentafluorobenzyl)hydroxylamine was tested as derivatisation agent, but no satisfactory results were obtained. Then, hollow-fibre liquid-phase microextraction (HF-LPME) and solid-phase microextraction were optimised. The HF-LPME method showed the highest sensitivity, achieving an enrichment factor of 60-fold. The limit of detection of the method was 10 ng g^-1, the limit of quantification was 30 ng g^-1 and the relative standard deviation was 6.1%. Finally, the method was applied to migration studies to evaluate the safety in use of a poly(ethylene terephthalate) packaging material. The content of isophthalaldehyde was determined in two aqueous food simulants: 10% ethanol (v/v) and 3% acetic acid (w/v). Different migration conditions were tested. The results obtained showed a considerable rise in the concentration of isophthalaldehyde when increasing the time and temperature of the migration experiment.