The Experts below are selected from a list of 38190 Experts worldwide ranked by ideXlab platform
Brian H. Clowers - One of the best experts on this subject based on the ideXlab platform.
-
augmenting Ion Trap mass spectrometers using a frequency modulated drift tube Ion mobility spectrometer
Analytical Chemistry, 2016Co-Authors: Kelsey A. Morrison, William F. Siems, Brian H. ClowersAbstract:Historically, high pressure Ion mobility drift tubes have suffered from low Ion duty cycles and this problem is magnified when such instrumentatIon is coupled with Ion Trap mass spectrometers. To significantly alleviate these issues, we outline the result from coupling an atmospheric pressure, dual-gate drift tube Ion mobility spectrometer (IMS) to a linear Ion Trap mass spectrometer (LIT-MS) via modulatIon of the Ion beam with a linear frequency chirp. The time-domain Ion current, once Fourier transformed, reveals a standard Ion mobility drift spectrum that corresponds to the standard mode of mobility analysis. By multiplexing the Ion beam, it is possible to successfully obtain drift time spectra for an assortment of simple peptide and protein mixtures using an LIT-MS while showing improved signal intensity versus the more common signal averaging technique. Explored here are the effects of maximum injectIon time, solutIon concentratIon, total experiment time, and frequency swept on signal-to-noise ratios...
-
augmenting Ion Trap mass spectrometers using a frequency modulated drift tube Ion mobility spectrometer
Analytical Chemistry, 2016Co-Authors: Kelsey A. Morrison, William F. Siems, Brian H. ClowersAbstract:Historically, high pressure Ion mobility drift tubes have suffered from low Ion duty cycles and this problem is magnified when such instrumentatIon is coupled with Ion Trap mass spectrometers. To significantly alleviate these issues, we outline the result from coupling an atmospheric pressure, dual-gate drift tube Ion mobility spectrometer (IMS) to a linear Ion Trap mass spectrometer (LIT-MS) via modulatIon of the Ion beam with a linear frequency chirp. The time-domain Ion current, once Fourier transformed, reveals a standard Ion mobility drift spectrum that corresponds to the standard mode of mobility analysis. By multiplexing the Ion beam, it is possible to successfully obtain drift time spectra for an assortment of simple peptide and protein mixtures using an LIT-MS while showing improved signal intensity versus the more common signal averaging technique. Explored here are the effects of maximum injectIon time, solutIon concentratIon, total experiment time, and frequency swept on signal-to-noise ratios...
Graham R Cooks - One of the best experts on this subject based on the ideXlab platform.
-
triple resonance methods to improve performance of Ion Trap precursor and neutral loss scans
Journal of the American Society for Mass Spectrometry, 2020Co-Authors: Lucas J Szalwinski, Dalton T Snyder, Mitchell J Wells, Graham R CooksAbstract:Two experiments are described that extend the capabilities of quadrupole Ion Trap mass spectrometers operated in the precursor and neutral loss scan mode. The first experiment, a triple resonance p...
-
calibratIon procedure for secular frequency scanning in Ion Trap mass spectrometers
Rapid Communications in Mass Spectrometry, 2016Co-Authors: Dalton T Snyder, Christopher J Pulliam, Graham R CooksAbstract:RatIonale Mass spectra can be recorded using Ion Traps by scanning the frequency of an alternating current (ac) signal that corresponds to the secular frequency of a Trapped Ion. There is a considerable simplificatIon in the instrumentatIon needed to perform such a scan compared with conventIonal scans of the radiofrequency (rf) amplitude. However, mass calibratIon is difficult. An algorithm that can be used to achieve mass calibratIon is investigated and the factors that affect Ion mass assignments are discussed. Methods Time domain data, recorded using a commercial benchtop linear Ion Trap mass spectrometer, are converted to the m/z domain using Ion Mathieu parameter qu values which are derived from the dimensIonless frequency parameter βu expressed as a continuing fractIon in terms of qu. The relatIonship between the operating parameters of an ideal Ion Trap and the Ion m/z ratio is derived from the Mathieu equatIons and expressed as an algorithm which through successive approximatIons yields the Mathieu qu value and hence m/z values and peak widths. The predictIons of the algorithm are tested against experiment by sweeping the frequency of a small supplementary ac signal so as to cause mass-selective ejectIon of Trapped Ions. Results CalibratIon accuracy is always better than 0.1%, often much better. Peak widths correspond to a mass resolutIon of 250 to 500 in the m/z 100–1800 range in secular frequency scans. ConclusIons A simple, effective method of calibratIon of mass spectra recorded using secular frequency scans is achieved. The effects of rf amplitude, scan rate, and ac amplitude on calibratIon parameters are shown using LTQ linear Ion Trap data. CorrectIons for differences in Ion mass must be made for accurate calibratIon, and this is easily incorporated into the calibratIon procedure. Copyright © 2016 John Wiley & Sons, Ltd.
-
experimental characterizatIon of secular frequency scanning in Ion Trap mass spectrometers
Journal of the American Society for Mass Spectrometry, 2016Co-Authors: Dalton T Snyder, Christopher J Pulliam, Joshua S Wiley, Jason Duncan, Graham R CooksAbstract:Secular frequency scanning is implemented and characterized using both a benchtop linear Ion Trap and a miniature rectilinear Ion Trap mass spectrometer. SeparatIon of tetraalkylammonium Ions and those from a mass calibratIon mixture and from a pesticide mixture is demonstrated with peak widths approaching unit resolutIon for optimized conditIons using the benchtop Ion Trap. The effects on the spectra of Ion Trap operating parameters, including waveform amplitude, scan directIon, scan rate, and pressure are explored, and peaks at black holes corresponding to nonlinear (higher-order field) resonance points are investigated. Reverse frequency sweeps (increasing mass) on the Mini 12 are shown to result in significantly higher Ion ejectIon efficiency and superior resolutIon than forward frequency sweeps that decrement mass. This result is accounted for by the asymmetry in Ion energy absorptIon profiles as a functIon of AC frequency and the shift in Ion secular frequency at higher amplitudes in the Trap due to higher order fields. We also found that use of higher AC amplitudes in forward frequency sweeps biases Ions toward ejectIon at points of higher order parametric resonance, despite using only dipolar excitatIon. Higher AC amplitudes also increase peak width and decrease sensitivity in both forward and reverse frequency sweeps. Higher sensitivity and resolutIon were obtained at higher Trap pressures in the secular frequency scan, in contrast to conventIonal resonance ejectIon scans, which showed the opposite trend in resolutIon on the Mini 12. Mass range is shown to be naturally extended in secular frequency scanning when ejecting Ions by sweeping the AC waveform through low frequencies, a method which is similar, but arguably superior, to the more usual method of mass range extensIon using low q resonance ejectIon.
-
handheld rectilinear Ion Trap mass spectrometer
Analytical Chemistry, 2006Co-Authors: Liang Gao, Graham R Cooks, Qingyu Song, Garth E Patterson, Zheng OuyangAbstract:A shoebox-sized, 10-kg, handheld mass spectrometer, Mini 10, based on a rectilinear Ion Trap mass analyzer has been designed, built, and characterized. This instrument has evolved from a decade-long experimental and simulatIon program in mass spectrometer miniaturizatIon. The rectilinear Ion Trap has a simplified geometry and high Trapping capacity, and when used with a miniature and ruggedized pumping system, it allows chemical analysis while the instrument is being carried. Compact electronics, including an air core RF drive coil, were developed to control the instrument and to record mass spectra. The instrument runs on battery power, consuming less than 70 W, similar to a laptop computer. Wired and wireless networking capabilities are implemented. The instrument gives unit resolutIon and a mass range of over m/z 500. Tandem mass spectrometry capabilities are implemented using collisIon-induced dissociatIon, and they are used to provide confirmatIon of chemical structure during in situ analysis. Contin...
-
rectilinear Ion Trap concepts calculatIons and analytical performance of a new mass analyzer
Analytical Chemistry, 2004Co-Authors: Zheng Ouyang, Yishu Song, Wolfgang R Plass, Graham R CooksAbstract:A mass analyzer based on a rectilinear geometry Ion Trap (RIT) has been built, and its performance has been characterized. Design concepts for this type of Ion Trap are delineated with emphasis on the effects of electrode geometry on the calculated electric field. The Mathieu stability regIon was mapped experimentally. The instrument can be operated using mass-selective instability scans in both the boundary and resonance ejectIon versIons. Comparisons of performance between different versIons of the device having different dimensIons allowed selectIon of an optimized geometry with an appropriate distributIon of higher-order electric fields. Comparisons made under the same conditIons between the performance of a conventIonal cylindrical Ion Trap and a RIT of 4 times greater volume show an improvement of 40 times in the signal-to-noise ratio resulting from the higher Ion Trapping capacity of the RIT. The demonstrated capabilities of the RIT include tandem mass spectrometry, a mass resolutIon in excess of 1...
Kelsey A. Morrison - One of the best experts on this subject based on the ideXlab platform.
-
augmenting Ion Trap mass spectrometers using a frequency modulated drift tube Ion mobility spectrometer
Analytical Chemistry, 2016Co-Authors: Kelsey A. Morrison, William F. Siems, Brian H. ClowersAbstract:Historically, high pressure Ion mobility drift tubes have suffered from low Ion duty cycles and this problem is magnified when such instrumentatIon is coupled with Ion Trap mass spectrometers. To significantly alleviate these issues, we outline the result from coupling an atmospheric pressure, dual-gate drift tube Ion mobility spectrometer (IMS) to a linear Ion Trap mass spectrometer (LIT-MS) via modulatIon of the Ion beam with a linear frequency chirp. The time-domain Ion current, once Fourier transformed, reveals a standard Ion mobility drift spectrum that corresponds to the standard mode of mobility analysis. By multiplexing the Ion beam, it is possible to successfully obtain drift time spectra for an assortment of simple peptide and protein mixtures using an LIT-MS while showing improved signal intensity versus the more common signal averaging technique. Explored here are the effects of maximum injectIon time, solutIon concentratIon, total experiment time, and frequency swept on signal-to-noise ratios...
-
augmenting Ion Trap mass spectrometers using a frequency modulated drift tube Ion mobility spectrometer
Analytical Chemistry, 2016Co-Authors: Kelsey A. Morrison, William F. Siems, Brian H. ClowersAbstract:Historically, high pressure Ion mobility drift tubes have suffered from low Ion duty cycles and this problem is magnified when such instrumentatIon is coupled with Ion Trap mass spectrometers. To significantly alleviate these issues, we outline the result from coupling an atmospheric pressure, dual-gate drift tube Ion mobility spectrometer (IMS) to a linear Ion Trap mass spectrometer (LIT-MS) via modulatIon of the Ion beam with a linear frequency chirp. The time-domain Ion current, once Fourier transformed, reveals a standard Ion mobility drift spectrum that corresponds to the standard mode of mobility analysis. By multiplexing the Ion beam, it is possible to successfully obtain drift time spectra for an assortment of simple peptide and protein mixtures using an LIT-MS while showing improved signal intensity versus the more common signal averaging technique. Explored here are the effects of maximum injectIon time, solutIon concentratIon, total experiment time, and frequency swept on signal-to-noise ratios...
James W Hager - One of the best experts on this subject based on the ideXlab platform.
-
high performance liquid chromatography tandem mass spectrometry with a new quadrupole linear Ion Trap instrument
Journal of Chromatography A, 2003Co-Authors: James W Hager, J Yves Le C BlancAbstract:The use of a new hybrid quadrupole/linear Ion Trap known as the Q Trap™ offers unique benefits as a LC–MS–MS detector for both small and large molecule analyses. The instrument combines the capabilities of a triple quadrupole mass spectrometer and Ion Trap technology on a single platform. Product Ion scans are conducted in a hybrid fashIon with the fragmentatIon step accomplished via acceleratIon into the collisIon cell followed by Trapping and mass analysis in the Q3 linear Ion Trap. This results in triple quadrupole fragmentatIon patterns with no inherent low molecular mass cutoff. In-Trap fragmentatIon is also possible in order to provide triple MS (MS3) capabilities. There are also several scan modes that are not possible on conventIonal instruments that enable identificatIon of analytes within complex biological matrixes for subsequent high sensitivity product Ion scans. This report will describe the new hybrid instrument and the principles of operatIon, and also provide examples of the unique scan modes and capabilities of the Q Trap™ for LC–MS–MS detectIon in metabolism identificatIon.
-
mass selective axial Ion ejectIon from a linear quadrupole Ion Trap
Journal of the American Society for Mass Spectrometry, 2003Co-Authors: Frank A Londry, James W HagerAbstract:The electric fields responsible for mass-selective axial ejectIon (MSAE) of Ions Trapped in a linear quadrupole Ion Trap have been studied using a combinatIon of analytic theory and computer modeling. Axial ejectIon occurs as a consequence of the Trapped Ions’ radial motIon, which is characterized by extrema that are phase-synchronous with the local RF potential. As a result, the net axial electric field experienced by Ions in the fringe regIon, over one RF cycle, is positive. This axial field depends strongly on both the axial and radial Ion coordinates. The superpositIon of a repulsive potential applied to an exit lens with the diminishing quadrupole potential in the fringing regIon near the end of a quadrupole rod array can give rise to an approximately conical surface on which the net axial force experienced by an Ion, averaged over one RF cycle, is zero. This conical surface has been named the cone of reflectIon because it divides the regIons of Ion reflectIon and Ion ejectIon. Once an Ion penetrates this surface, it feels a strong net positive axial force and is accelerated toward the exit lens. As a consequence of the strong dependence of the axial field on radial displacement, Trapped thermalized Ions can be ejected axially from a linear Ion Trap in a mass-selective way when their radial amplitude is increased through a resonant response to an auxiliary signal.
-
a new linear Ion Trap mass spectrometer
Rapid Communications in Mass Spectrometry, 2002Co-Authors: James W HagerAbstract: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.
William F. Siems - One of the best experts on this subject based on the ideXlab platform.
-
augmenting Ion Trap mass spectrometers using a frequency modulated drift tube Ion mobility spectrometer
Analytical Chemistry, 2016Co-Authors: Kelsey A. Morrison, William F. Siems, Brian H. ClowersAbstract:Historically, high pressure Ion mobility drift tubes have suffered from low Ion duty cycles and this problem is magnified when such instrumentatIon is coupled with Ion Trap mass spectrometers. To significantly alleviate these issues, we outline the result from coupling an atmospheric pressure, dual-gate drift tube Ion mobility spectrometer (IMS) to a linear Ion Trap mass spectrometer (LIT-MS) via modulatIon of the Ion beam with a linear frequency chirp. The time-domain Ion current, once Fourier transformed, reveals a standard Ion mobility drift spectrum that corresponds to the standard mode of mobility analysis. By multiplexing the Ion beam, it is possible to successfully obtain drift time spectra for an assortment of simple peptide and protein mixtures using an LIT-MS while showing improved signal intensity versus the more common signal averaging technique. Explored here are the effects of maximum injectIon time, solutIon concentratIon, total experiment time, and frequency swept on signal-to-noise ratios...
-
augmenting Ion Trap mass spectrometers using a frequency modulated drift tube Ion mobility spectrometer
Analytical Chemistry, 2016Co-Authors: Kelsey A. Morrison, William F. Siems, Brian H. ClowersAbstract:Historically, high pressure Ion mobility drift tubes have suffered from low Ion duty cycles and this problem is magnified when such instrumentatIon is coupled with Ion Trap mass spectrometers. To significantly alleviate these issues, we outline the result from coupling an atmospheric pressure, dual-gate drift tube Ion mobility spectrometer (IMS) to a linear Ion Trap mass spectrometer (LIT-MS) via modulatIon of the Ion beam with a linear frequency chirp. The time-domain Ion current, once Fourier transformed, reveals a standard Ion mobility drift spectrum that corresponds to the standard mode of mobility analysis. By multiplexing the Ion beam, it is possible to successfully obtain drift time spectra for an assortment of simple peptide and protein mixtures using an LIT-MS while showing improved signal intensity versus the more common signal averaging technique. Explored here are the effects of maximum injectIon time, solutIon concentratIon, total experiment time, and frequency swept on signal-to-noise ratios...
