Collision-Induced Dissociation Study of the Adduct Ions Produced in NO3−-Free Area of Atmospheric Pressure Negative Corona Discharges under Ambient Air Conditions

摘要

Collision-induced dissociation (CID) experiments of adducts [M+R]⁻ with negative atmospheric ions R⁻ (O2⁻, HCO3⁻ and COO⁻(COOH)) produced in NO3⁻-free discharge area in atmospheric pressure corona discharge ionization (APCDI) method were performed using aliphatic and aromatic compounds M. The [M+R]⁻ adducts for individual R⁻ fragmented to form deprotonated analytes [M−H]⁻ as well as the specific product ions which also occurred in the CID of [M−H]⁻, independent of analytes with several different functional groups. The results obtained suggested that the specific product ions formed in the CID of [M+R]⁻, as well as CID of [M−H]⁻, are generated due to further fragmentation of the product ions [M−H]⁻. It was concluded, therefore, that CID of [M+R]⁻ formed in NO3⁻-free discharge area can indirectly lead to the formation of the product ions originating from [M−H]⁻.