SGMS Meeting 2000

HPLC-multiple mass spectrometry (MSⁿ), a useful tool for the on-line structure elucidation of oligomers of bisphenol A diglycidyl ether (BADGE) and Novolac glycidyl ether (NOGE) migrating from can coatings into food

Michael Oehme, Urs Berger, Michael Oehme and Line Girardin
Organic Analytical Chemistry, University of Basel, Neuhausstrasse 31, CH-4057 Basel, Switzerland

Bisphenol A diglycidyl ether (BADGE) is a common starting material for the production of internal coatings of food and beverage cans. In the production process of the varnishes reactions with chain terminating agents, solvents and catalysts occur leading to a complex mixture of oligomeric derivatives. Depending on the degree of cross-linking of the resin, migration of these substances into food is possible, where further reaction products with food components might be formed. BADGE and novolac glycidyl ether (NOGE) are also used as scavengers to remove hydrochloric acid released from polyvinyl chloride (PVC)-based lacquers by degradation.

Extracts of can coatings as well as of canned food can contain dozens of oligomeric reaction products. So far, their structures were mostly unknown. Reversed phase HPLC combined with ion trap multiple mass spectrometry (MSⁿ) was considered as a very promising tool to elucidate the structures of such BADGE and NOGE derivatives with molecular weights between 300 and 2000 u. Up to 60 different compounds deriving from BADGE and NOGE were detectable in single extracts from inner coatings of empty cans extracted with acetonitrile. Atmospheric pressure chemical ionisation in the positive ion mode generated almost exclusively ammonium/molecule adduct ions. MS² and MS³ spectra allowed to identify BADGE or NOGE backbone structures due to typical fragmentation patterns. In addition, structure relevant ions were present enabling a complete structure elucidation for many substances.

This information allowed to identify the type of varnish used as well as applied additives. PVC-based can coatings were considered most problematic due to the release of a high number of low molecular weight substances, among them epoxides and chlorinated compounds of unknown toxicity.

Due to less variations in the response factors of the identified compounds, fluorescence detection was found most suitable for quantification. It was connected in series in front of the mass spectrometer. A simple and fast extraction method was developed to investigate canned tuna as well as the surrounding oil. The structures of identified compound will be presented as well as an estimate of the quantities found.

U. Berger and M. Oehme. Identification of derivatives of bisphenol A diglycidyl ether (BADGE) and novolac glycidyl ether (NOGE) in can coatings by HPLC/ion trap mass spectrometry. J. of AOAC Int. in press.