Ion chemistry of phthalates in selected ion flow tube mass spectrometry: isomeric effects and secondary reactions with water vapour

• DOI: 10.1039/d0cp00538j
• Publication Date: 2020-07-10T09:23:32Z
• Authors: Michal Lacko; Bartosz Michalczuk; Štefan Matejčík; Patrik Španěl
• Keywords: chemical-ionization; ptr-ms; affinities; no+; air; 01 natural sciences; organic-compounds; 0104 chemical sciences; esters; h3o+; sift-ms; molecules

Phthalates are widely industrially used and their toxicity is of serious environmental public health concern. Chemical ionization (CI) analytical techniques offer the potential to detect monitor traces phthalate vapours in air or sample headspace real time. Promising include selected ion flow tube mass spectrometry (SIFT-MS), proton transfer reaction (PTR-MS) mobility (IMS). To facilitate such analyses, reactions H3O+, O2+ NO+ reagent ions with molecules need be understood. Thus, chemistry dimethyl isomers (dimethyl phthalate, DMP - ortho; isophthalate, DMIP meta; terephthalate, DMTP para), diethyl (DEP), dipropyl (DPP) dibutyl (DBP) was studied by SIFT-MS. Reactions these M were found produce characteristic primary products MH+, M+ MNO+, respectively. In addition, a dissociation process forming (M-OR)+ fragment observed. For phthalates longer alkyl chains, mainly DPP DBP, secondary channel triggered McLafferty rearrangement also However, this dominant only for more energetic phthalates, additionally resulting recognisable formation protonated anhydride. ions, makes minor contribution it not Experiments on effect water vapour have shown that efficiently associate H2O DMIP·H+H2O, DMIP·H+(H2O)2 DMTP·H+H2O cluster whilst ortho isomer as well other DEP, DBP does H2O. The results indicate degree hydration can identify specific CI.