Characteristics of Charge Exchange Chemical Ionization (CI) in an Atmospheric Pressure Gas Chromatography (APGC) Source and Applied Uses

摘要

Systematic investigation of optimum charge exchange conditions for the APGC source led to the determination of optimum operating conditions and provided insight into the interplay between parameters. By combining charge exchange ionization with MS~E acquisition mode, it was possible to acquire accurate mass measured intact molecular ion and fragmentation data while also providing the ability to compare fragmentation data, generated through CID of M~+. molecular ions, to NIST EI library spectra. Since the molecular ion formed using charge exchange CI is the same form as molecular ions formed by EI (when present at all) then the product ions generated upon CID are shown to be predominantly the same. Petroleum biomarker analysis performed using EI GC/MRM and atmospheric pressure charge exchange CI GC/MRM was demonstrated to be able to use the same MRM transitions for the determination of cyclic biomarkers. Sensitive detection of TCDD was demonstrated using charge exchange with APGC operated in MRM mode by applying the same transitions as used with EI GC/ MRM.