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Chen T.,Florida State University | Beu S.C.,S. C. Beu Consulting | Kaiser N.K.,Florida State University | Hendrickson C.L.,Florida State University
Review of Scientific Instruments | Year: 2014

A conventional Fourier transform-Ion Cyclotron Resonance (ICR) detection cell is azimuthally divided into four equal sections. One pair of opposed electrodes is used for ion cyclotron excitation, and the other pair for ion image charge detection. In this work, we demonstrate that an appropriate electrical circuit facilitates excitation and detection on one pair of opposed electrodes. The new scheme can be used to minimize the number of electrically independent ICR cell electrodes and/or improve the electrode geometry for simultaneously increased ICR signal magnitude and optimal post-excitation radius, which results in higher signal-to-noise ratio and decreased space-charge effects. © 2014 AIP Publishing LLC.

Hendrickson C.L.,Florida State University | Quinn J.P.,Florida State University | Kaiser N.K.,Florida State University | Smith D.F.,Florida State University | And 5 more authors.
Journal of the American Society for Mass Spectrometry | Year: 2015

We describe the design and initial performance of the first 21 tesla Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The 21 tesla magnet is the highest field superconducting magnet ever used for FT-ICR and features high spatial homogeneity, high temporal stability, and negligible liquid helium consumption. The instrument includes a commercial dual linear quadrupole trap front end that features high sensitivity, precise control of trapped ion number, and collisional and electron transfer dissociation. A third linear quadrupole trap offers high ion capacity and ejection efficiency, and rf quadrupole ion injection optics deliver ions to a novel dynamically harmonized ICR cell. Mass resolving power of 150,000 (m/Δm 50% ) is achieved for bovine serum albumin (66 kDa) for a 0.38 s detection period, and greater than 2,000,000 resolving power is achieved for a 12 s detection period. Externally calibrated broadband mass measurement accuracy is typically less than 150 ppb rms, with resolving power greater than 300,000 at m/z 400 for a 0.76 s detection period. Combined analysis of electron transfer and collisional dissociation spectra results in 68% sequence coverage for carbonic anhydrase. The instrument is part of the NSF High-Field FT-ICR User Facility and is available free of charge to qualified users. [Figure not available: see fulltext.] © 2015 American Society for Mass Spectrometry.

Xian F.,Florida State University | Hendrickson C.L.,Florida State University | Hendrickson C.L.,CNRS French National High Magnetic Field Laboratory | Blakney G.T.,CNRS French National High Magnetic Field Laboratory | And 3 more authors.
Analytical Chemistry | Year: 2010

It has been known for 35 years that phase correction of FTICR data can in principle produce an absorption-mode spectrum with mass resolving power as much as a factor of 2 higher than conventional magnitude-mode display, an improvement otherwise requiring a (much more expensive) increase in magnetic field strength. However, temporally dispersed excitation followed by time-delayed detection results in steep quadratic variation of signal phase with frequency. Here, we present a robust, rapid, automated method to enable accurate broadband phase correction for all peaks in the mass spectrum. Low-pass digital filtering effectively eliminates the accompanying baseline roll. Experimental FTICR absorption-mode mass spectra exhibit at least 40% higher resolving power (and thus an increased number of resolved peaks) as well as higher mass accuracy relative to magnitude mode spectra, for more complete and more reliable elemental composition assignments for mixtures as complex as petroleum. © 2010 American Chemical Society.

Xian F.,CNRS French National High Magnetic Field Laboratory | Valeja S.G.,Florida State University | Beu S.C.,S. C. Beu Consulting | Hendrickson C.L.,CNRS French National High Magnetic Field Laboratory | And 3 more authors.
Journal of the American Society for Mass Spectrometry | Year: 2013

Fourier transform mass spectrometry (FTMS) of the isolated isotopic distribution for a highly charged biomolecule produces time-domain signal containing large amplitude signal "beats" separated by extended periods of much lower signal magnitude. Signal-to-noise ratio for data sampled between beats is low because of destructive interference of the signals induced by members of the isotopic distribution. Selective blanking of the data between beats has been used to increase spectral signal-to-noise ratio. However, blanking also eliminates signal components and, thus, can potentially distort the resulting FT spectrum. Here, we simulate the time-domain signal from a truncated isotopic distribution for a single charge state of an antibody. Comparison of the FT spectra produced with or without blanking and with or without added noise clearly show that blanking does not improve mass accuracy and introduces spurious peaks at both ends of the isotopic distribution (thereby making it more difficult to identify posttranslational modifications and/or adducts). Although the artifacts are reduced by use of multiple Gaussian (rather than square wave) windowing, blanking appears to offer no advantages for identifying true peaks or for mass measurement. [Figure not available: see fulltext.] © 2013 American Society for Mass Spectrometry.

Beu S.C.,S. C. Beu Consulting | Hendrickson C.L.,Florida State University | Marshall A.G.,Florida State University
Journal of the American Society for Mass Spectrometry | Year: 2011

Radiofrequency (rf)multipole ion guides arewidely used to transfer ions through the strongmagnetic field gradient between source and analyzer regions of external source Fourier transform ion cyclotron resonance mass spectrometers. Although ion transfer as determined solely by the electric field in a multipole ion guide has been thoroughly studied, transfer influenced by immersion in a strong magnetic field gradient has not been as well characterized. Recent work has indicated that the addedmagnetic field can have profound effects on ion transfer, ultimately resulting in loss of ions initially contained within themultipole. Those losses result fromradial ejection of ions due to transient cyclotron resonance that occurs when ions traverse a region in which themagnetic field results in an effective cyclotron frequency equal to the multipole rf drive frequency divided by the multipole order (multipole order is equal to one-half the number of poles). In this work, we describe the analytical basis for ion resonance in a rfmultipole ion guide with superposed static magnetic field and compare with results of numerical trajectory simulations. © American Society for Mass Spectrometry,2011.

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