Rapid screening of migrants from food contact plastics using electrospray ionization mass spectrometry

Abstract

Migration from food contact plastics is currently assessed by an over-all migration test based on ‘weight-loss’ determinations. This test was introduced as an alternative to the large number of analytical tests which might be required if each ingredient had a specific migration limit. The gravimetric determination is, however, inappropriate for toxic species where very low specific migration limits are specified. Several different tests may therefore be required to demonstrate compliance with the legislation. Modern HPLC techniques may be able to separate all the individual components which constitute the over-all migration. These can be quantified to give the over-all migration value or dealt with individually if a specific migration criterion is appropriate. Identification of these components can be achieved either by chromatographic separation (retention time) or by mass spectrometry using soft ionization techniques to produce characteristic molecular ions. It is conceivable, therefore, that an automated system capable of determining several migration criteria from a single measurement could reduce analysis time and, in a situation where many samples are tested, lead to more cost-effective investigations.

Some initial tests of this hypothesis were carried out by using mass spectrometers equipped with either electrospray or atmospheric pressure ionization interfaces in order to produce molecular ions for compound identification without recourse to chromatographic separation. In these tests a range of antioxidants commonly added to polymers were used to produce calibration data. By use of this information the presence of different combinations of antioxidants was correctly identified in a series of test solutions and in samples obtained from migration experiments using commercial plastics. Analysis time was less than 10% of that required for the conventional HPLC analysis of the migrants.