title: Multiplexed four-channel rectilinear ion trap mass spectrometer.
abstract: A four-channel multiplexed mass spectrometer with rectilinear ion trap (RIT) mass analyzers was designed, constructed, and characterized. The system consists of four parallel atmospheric pressure ion (API) sources, four RIT mass analyzers, four sets of ion optical elements, and four conversion dynode detectors. The complete instrument is housed in a single vacuum manifold with a common vacuum system. It has a relatively small footprint, and costs and complexity were minimized and controls simplified by sharing the electronics and control modules among different channels. Each channel of the instrument can be operated in either positive or negative ion mode with a choice of ionization methods to improve the information content from an experiment. Also, the instrument is equipped with simultaneous data acquisition capabilities from all four channels, but the use of a common RF electronics system limits the degree to which the analyzer channels can be scanned independently. The instrument was characterized over the mass/charge range of 150 to 1300 Th. Mass misassignments in different ion traps because of machining and assembly tolerances were avoided by the application of supplementary direct current signals to each mass analyzer to correct mass offsets. A multiplexed automatic gain control (AGC) scheme was developed to control the ion population in each of the traps independently. These two features allow tandem mass spectrometry to be performed with an isolation window of 1 Th so trapping identical ions in all four channels. There are two principal modes of operation. In one, the same sample is analyzed in all four channels using different ionization methods to increase the information content of the analysis. In the other mode of operation, different samples are analyzed in all four channels with the same ionization method, so providing higher throughput. These capabilities were demonstrated by examining lipids produced by Escherichia coli and complex mixtures containing drugs of abuse.
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, USA.
authors.forename: Sameer
authors.initials: S
authors.lastname: Kothari
authors.forename: Qingyu
authors.initials: Q
authors.lastname: Song
authors.forename: Yu
authors.initials: Y
authors.lastname: Xia
authors.forename: Miriam
authors.initials: M
authors.lastname: Fico
authors.forename: Dennis
authors.initials: D
authors.lastname: Taylor
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Amy
authors.forename: George
authors.initials: G
authors.lastname: Stafford
authors.forename: R Graham
authors.initials: RG
authors.lastname: Cooks
mesh_terms: D001274:Atmospheric Pressure; D045424:Complex Mixtures / Q000032:analysis; D004581:Electronics; D048168:Escherichia coli K12 / Q000737:chemistry; D008055:Lipids / Q000032:analysis; D013058:Mass Spectrometry / Q000379:methods*; D055620:Optical Phenomena; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D045424:Complex Mixtures; D008055:Lipids