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Linear Ion Trap Mass Spectrometer (linear + ion_trap_mass_spectrometer)
Selected AbstractsThin-layer chromatography/electrospray ionization triple-quadrupole linear ion trap mass spectrometry system: analysis of rhodamine dyes separated on reversed-phase C8 plates ,JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 7 2005Michael J. Ford Abstract The direct analysis of separated rhodamine dyes on reversed-phase C8 thin-layer chromatography plates using a surface sampling/electrospray emitter probe coupled with a triple-quadrupole linear ion trap mass spectrometer is presented. This report represents continuing work to advance the performance metrics and utility of this basic surface sampling electrospray mass spectrometry system for the analysis of thin-layer chromatography plates. Experimental results examining the role of sampling probe spray end configuration on liquid aspiration rate and gas-phase ion signal generated are discussed. The detection figures-of-merit afforded by full-scan, automated product ion and selected reaction monitoring modes of operation were examined. The effect of different eluting solvents on mass spectrum signal levels with the reversed-phase C8 plate was investigated. The combined effect of eluting solvent flow-rate and development lane surface scan rate on preservation of chromatographic resolution was also studied. Analysis of chromatographically separated red pen ink extracts from eight different pens using selected reaction monitoring demonstrated the potential of this surface sampling electrospray mass spectrometry system for targeted compound analysis with real samples. Copyright © 2005 John Wiley & Sons, Ltd. [source] Rapid screening and characterization of drug metabolites using a new quadrupole,linear ion trap mass spectrometerJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 2 2003Gérard Hopfgartner Abstract The application of a new hybrid RF/DC quadrupole,linear ion trap mass spectrometer to support drug metabolism and pharmacokinetic studies is described. The instrument is based on a quadrupole ion path and is capable of conventional tandem mass spectrometry (MS/MS) as well as several high-sensitivity ion trap MS scans using the final quadrupole as a linear ion trap. Several pharmaceutical compounds, including trocade, remikiren and tolcapone, were used to evaluate the capabilities of the system with positive and negative turbo ionspray, using either information-dependent data acquisition (IDA) or targeted analysis for the screening, identification and quantification of metabolites. Owing to the MS/MS in-space configuration, quadrupole-like CID spectra with ion trap sensitivity can be obtained without the classical low mass cutoff of 3D ion traps. The system also has MS3 capability which allows fragmentation cascades to be followed. The combination of constant neutral loss or precursor ion scan with the enhanced product ion scan was found to be very selective for identifying metabolites at the picogram level in very complex matrices. Owing to the very high cycle time and, depending on the mass range, up to eight different MS experiments could be performed simultaneously without compromising chromatographic performance. Targeted product ion analysis was found to be complementary to IDA, in particular for very low concentrations. Comparable sensitivity was found in enhanced product ion scan and selected reaction monitoring modes. The instrument is particularly suitable for both qualitative and quantitative analysis. Copyright © 2003 John Wiley & Sons, Ltd. [source] Unimolecular dissociation of protonated trans -1,4-diphenyl-2-butene-1,4-dione in the gas phase: rearrangement versus simple cleavageRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 17 2006Lianming Wu Fragmentation mechanisms of trans -1,4-diphenyl-2-butene-1,4-dione were studied using a variety of mass spectrometric techniques. The major fragmentation pathways occur by various rearrangements by loss of H2O, CO, H2O and CO, and CO2. The other fragmentation pathways via simple alpha cleavages were also observed but accounted for the minor dissociation channels in both a two-dimensional (2-D) linear ion trap and a quadrupole time-of-flight (Q-TOF) mass spectrometer. The elimination of CO2 (rather than CH3CHO or C3H8), which was confirmed by an exact mass measurement using the Q-TOF instrument, represented a major fragmentation pathway in the 2-D linear ion trap mass spectrometer. However, the elimination of H2O and CO becomes more competitive in the beam-type Q-TOF instrument. The loss of CO is observed in both the MS2 experiment of m/z 237 and the MS3 experiment of m/z 219 but via the different transition states. The data suggest that the olefinic double bond in protonated trans -1,4-diphenyl-2-butene-1,4-dione plays a key role in stabilizing the rearrangement transition states and increasing the bond dissociation (cleavage) energy to give favorable rearrangement fragmentation pathways. Copyright © 2006 John Wiley & Sons, Ltd. [source] Ultra-performance liquid chromatography coupled to linear ion trap mass spectrometry for the identification of drug metabolites in biological samplesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 8 2006G. J. Dear The coupling of ultra-performance liquid chromatography, operating at elevated pressures, to a linear ion trap mass spectrometer provides a high-performance system suitable for drug metabolite characterisation. This system demonstrates improved chromatographic efficiency and sensitivity and at the same time provides diagnostic MSn data often critical for metabolite structural assignment. The linear ion trap was capable of dealing with the high chromatographic efficiencies and hence narrow peak widths associated with 1.7,µm particle-packed column separations. Polarity switching and data-dependent MSn data were generated with ease, and applied to the identification of metabolites found in human plasma. Copyright © 2006 John Wiley & Sons, Ltd. [source] An integrated strategy for identification and relative quantification of site-specific protein phosphorylation using liquid chromatography coupled to MS2/MS3RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 24 2005Florian Wolschin Reversible and differential multisite protein phosphorylation is an important mechanism controlling the activity of cellular proteins. Here we describe a robust and highly selective approach for the identification and relative quantification of site-specific phosphorylation events. This integrated strategy has three major parts: visualisation of phosphorylated proteins using fluorescently stained polyacrylamide gels, determination of the phosphorylation site(s) using automatic MS3 triggered by the loss of phosphoric acid, and relative quantification of phosphorylation by integrating MS2 - and MS3 -extracted ion traces using a fast-scanning, linear ion trap mass spectrometer. As a test case, recombinant sucrose-phosphate synthase (SPS) from Arabidopsis thaliana (At5g1110) was used for identification and quantification of site-specific phosphorylation. The identified phosphorylation site of the actively expressed protein coincides with the major regulatory in vivo phosphorylation site in spinach SPS. Site-specific differential in vitro phosphorylation of native protein was demonstrated after incubation of the recombinant protein with cold-adapted plant leaf extracts from A. thaliana, suggesting regulatory phosphorylation events of this key enzyme under stress response. Copyright © 2005 John Wiley & Sons, Ltd. [source] A new linear ion trap mass spectrometerRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 6 2002James W. Hager Characteristics of mass selective axial ion ejection from a linear quadrupole ion trap in the presence of an auxiliary quadrupole field are described. Ion ejection is shown to occur through coupling of radial and axial motion in the exit fringing fields of the linear ion trap. The coupling is efficient and can result in extraction of as much as 20% of the trapped ions. This, together with the very high trapping efficiencies, can yield high sensitivity mass spectral responses. The experimental apparatus is based on the ion path of a triple quadrupole mass spectrometer allowing either the q2 collision cell or the final mass analysis quadrupole to be used as the linear trap. Space charge induced distortions of the mass resolved features while using the pressurized q2 linear ion trap occur at approximately the same ion density as reported for conventional three-dimensional ion traps. These distortions are, however, much reduced for the lower pressure linear trap possibly owing to the proposed axial ejection mechanism that leads to ion ejection only for ions of considerable radial amplitude. RF heating due to the high ejection q -value and the low collision frequency may also contribute. Two hybrid RF/DC quadrupole-linear ion trap instruments are described that provide high sensitivity product ion scanning while operated in the linear ion trap mode while also retaining all conventional triple quadrupole scan modes such as precursor ion and neutral loss scan modes. Copyright © 2002 John Wiley & Sons, Ltd. [source] | ||||||||||