Combined gas chromatography-chemical-ionisation mass spectrometry of some phthalate esters

Abstract

A sample mixture of seven phthalate esters was analysed using combined gas chromatography-chemical-ionisation mass spectrometry (GC-CIMS). Separation of the various components of the mixture was effected by gas chromatography and subsequent identification by chemical-ionisation mass spectrometry using methane and isobutane as reagent gases.

Comparison of electron-impact (EI) spectra and the CI spectra was under-taken in order to illustrate the advantage of CIMS over EIMS in identifying these phthalate esters. CIMS with isobutane gives abundant quasi-molecular ions, [M + H]⁺, with no adduct ions formed, in contrast to CIMS with methane, and thus provides a means of distinguishing between isomeric phthalate esters.