Analysis of unknowns in recycled LDPE plastic by LC-Orbitrap Tribrid HRMS using MS3 with an intelligent data acquisition mode

A new automated approach has been developed for the fast investigation of unknown substances (NIAS/IAS) in recycled LDPE plastic that could be used for food contact material (FCM). The pipeline setup includes an intelligent data acquisition with AcquireX (TM) linked to LC-Orbitrap Tribrid-HRMS (MS3) and coupled to Compound Discoverer data processing. Twenty-eight unknown compounds were tentatively identified using very restrictive criteria that includes exact mass, isotopic profile, MS2 match, retention time and MS3 match. Most of the identified compounds were additives, mainly plasticizers, used in different plastic applications. To check for the safety of the migration of these compounds for food contact material applications of the LDPE recycled plastic, a risk assessment was performed using mainly the threshold of toxicological concern (TTC) approach. The migration of the identified compounds does not represent a risk.