LC-MS analysis of polymer additives by electron and atmospheric-pressure ionization: Identification and quantification

A mass spectrometer can be the ideal detector for liquid chromatography (LC ) because it offers both universality and the necessary selectivity for com plex analytical problems. The two most popular types of interfaces for benc h-top single-quadrupole LC-mass spectrometry (MS) systems are the particle beam and the atmospheric-pressure ionization interfaces. The particle beam interface is used to generate electron ionization spectra and the atmospher ic-pressure ionization interface is used to generate either electrospray or atmospheric-pressure chemical ionization spectra. In this article, the aut hors chose the organic extractables from polypropylene as their model analy tes to demonstrate how the information obtained separately from electron an d atmospheric-pressure ionization can be complementary. They separated and detected seven compounds using both MS detectors. With the classic spectrum from electron ionization and molecular weight information from atmospheric -pressure chemical ionization, they proposed the identities of all seven an alytes. Positive confirmation was obtained with varying degrees of confiden ce depending upon the method of use. They also quantified the additives usi ng atmospheric-pressure chemical ionization. Four of the seven analytes wer e quantified with their standards.