4. Conclusions
The use of two different and complementary ionization sources
(EI and APCI) in GC–(Q)TOF MS has notably enhanced the identifi-
cation potential of food packaging contaminants by performing a
non-target analysis. The analysis by GC–(APCI)QTOF MS allowed
reducing considerably the number of candidates previously proposed
by GC–(EI)TOF MS, thus obtaining a reliable approach to
the compounds identity. In some cases, around half of candidates
from a detected peak by (EI)TOF could be rejected after searching
for the molecular ion/protonated molecule in (APCI)QTOF and/or
studying the fragmentation under these conditions. In order to
get an unequivocal confirmation, the injection of available reference
standards was performed, which allowed the confirmation
of the identity of 8 migrants.
In most cases, the difficulty of arriving to conclusive results was
evident in this kind of samples due to the extensive list of possible
structures that are compatible with the data acquired, especially
due to the isomeric nature of most candidates. Identification of
unknowns is a challenge and, in addition, when standards are
available their acquisition involves a considerable expense without
ensuring conclusions, but the powerful combination of techniques
applied in this work allowed a rapid screening that simplified and
facilitated the identification process.