title: Fast transient analysis and first-stage collision-induced dissociation with the  flowing atmospheric-pressure afterglow ionization source to improve  analyte detection and identification.
abstract: The recent development of ambient desorption/ionization mass spectrometry (ADI-MS) has enabled fast, simple analysis of many different sample types. The ADI-MS sources have numerous advantages, including little or no required sample pre-treatment, simple mass spectra, and direct analysis of solids and liquids. However, problems of competitive ionization and limited fragmentation require sample-constituent separation, high mass accuracy, and/or tandem mass spectrometry (MS/MS) to detect, identify, and quantify unknown analytes. To maintain the inherent high throughput of ADI-MS, it is essential for the ion source/mass analyzer combination to measure fast transient signals and provide structural information. In the current study, the flowing atmospheric-pressure afterglow (FAPA) ionization source is coupled with a time-of-flight mass spectrometer (TOF-MS) to analyze fast transient signals (<500 ms FWHM). It was found that gas chromatography (GC) coupled with the FAPA source resulted in a reproducible (<5% RSD) and sensitive (detection limits of <6 fmol for a mixture of herbicides) system with analysis times of ca. 5 min. Introducing analytes to the FAPA in a transient was also shown to significantly reduce matrix effects caused by competitive ionization by minimizing the number and amount of constituents introduced into the ionization source. Additionally, MS/MS with FAPA-TOF-MS, enabling analyte identification, was performed via first-stage collision-induced dissociation (CID). Lastly, molecular and structural information was obtained across a fast transient peak by modulating the conditions that caused the first-stage CID.
authors.affiliation: Department of Chemistry, 800 E. Kirkwood Ave., Bloomington, IN, USA.
authors.forename: Jacob T
authors.initials: JT
authors.lastname: Shelley
authors.forename: Gary M
authors.initials: GM
authors.lastname: Hieftje
mesh_terms: D001577:Benzophenones / Q000737:chemistry; D002849:Chromatography, Gas; D006540:Herbicides / Q000032:analysis / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000295:instrumentation / Q000379:methods*
chemical_list: D001577:Benzophenones; D006540:Herbicides; C047723:benzophenone