Collision-induced dissociation analysis of negative atmospheric ion adducts in atmospheric pressure corona discharge ionization mass spectrometry

摘要

Collision-induced dissociation (CID) experiments were performed on atmospheric ion adducts [M + R]- formed between various types of organic compounds M and atmospheric negative ions R- [such as O_2~-, HCO_3~-, COO~-(COOH), NO_2~-, NO_3~-, and NO_3~-(HNO_3)] in negative-ion mode atmospheric pressure corona discharge ionization (APCDI) mass spectrometry. All of the [M + R]- adducts were fragmented to form deprotonated analytes [M - H]- and/or atmospheric ions R-, whose intensities in the CID spectra were dependent on the proton affinities of the [M - H]- and R- fragments. Precursor ions [M + R]- for which R- have higher proton affinities than [M - H]- formed [M - H]- as the dominant product. Furthermore, the CID of the adducts with HCO_3~- and NO_3~-(HNO_3) led to other product ions such as [M + HO]- and NO_3~-, respectively. The fragmentation behavior of [M + R]- for each R - observed was independent of analyte type (e.g.; whether the analyte was aliphatic or aromatic, or possessed certain functional groups). [Figure not available: see fulltext.]