High-Mass Accuracy of Product Ions Produced by SORI-CID Using a Dual Electrospray Ionization Source Coupled with FTICR Mass Spectrometry

177

146

The advent of soft ionization techniques, notably electrospray and laser desorption ionization methods, has enabled the extension of mass spectrometric methods to large molecules and molecular complexes. This both greatly extends the applications of mass spectrometry and makes the activation and dissociation of complex ions an integral part of these applications. This review emphasizes the most promising methods for activation and dissociation of complex ions and presents this discussion in the context of general knowledge of reaction kinetics and dynamics largely established for small ions. We then introduce the characteristic differences associated with the higher number of internal degrees of freedom and high density of states associated with molecular complexity. This is reflected primarily in the kinetics of unimolecular dissociation of complex ions, particularly their slow decay and the higher energy content required to induce decomposition-the kinetic shift (KS). The longer trapping time of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) significantly reduces the KS, which presents several advantages over other methods for the investigation of dissociation of complex molecules. After discussing general principles of reaction dynamics related to collisional activation of ions, we describe conventional ways to achieve single-and multiple-collision activation in FT-ICR MS. Sustained off-resonance irradiation (SORI)-the simplest and most robust means of introducing the multiple collision activation process-is discussed in greatest detail. Details of implementation of this technique, required control of experimental parameters, limitations, and examples of very successful application of SORI-CID are described. The advantages of high mass resolving power and the ability to carry out several stages of mass selection and activation intrinsic to FT-ICR MS are demonstrated in several examples. Photodissociation of ions from small molecules can be effected using IR or UV/vis lasers and generally requires tuning lasers to specific wavelengths and/ or utilizing high flux, multiphoton excitation to match energy levels in the ion. Photodissociation of complex ions is much easier to accomplish from the basic physics perspective. The quasi-continuum of vibrational states at room temperature makes it very easy to pump relatively large amounts of energy into complex ions and infrared multiphoton dissociation (IRMPD) is a powerful technique for characterizing large ions, particularly biologically relevant molecules. Since both SORI-CID and IRMPD are slow activation methods they have many common characteristics. They are also distinctly different because SORI-CID is intrinsically selective (only ions that have a cyclotron frequency close to the frequency of the excitation field are excited), whereas IRMPD is not (all ions that reside on the optical path of the laser are excited). There are advantages and disadvantages to each technique and in many applications they complement each other. In contrast wi...

Section: Activation Of Large Ions In Ft-icrmsmentioning

confidence: 98%

Section: High Mass Accuracymentioning

confidence: 99%

Activation of large lons in FT‐ICR mass spectrometry

Laskin

Futrell

2004

177

146

“…In a subsequent study, Muddiman and co-workers modified a previously developed dual ESI source (Flora, Hannis, & Muddiman, 2001;Hannis & Muddiman, 2000;Nepomuceno et al, 2003;Williams, Hawkridge, & Muddiman, 2007a) for generation of both analyte cation and ETD reagent anion populations (Williams et al, 2007b). In this device, the ESI emitters are alternatively positioned in front of the atmospheric pressure inlet of the LTQ-Orbitrap, as opposed to the stationary configurations described above in which the ESI voltages are alternately pulsed on and off during an experiment.…”

Section: A Proteomicsmentioning

confidence: 99%

Orbitrap mass spectrometry: Instrumentation, ion motion and applications

Perry

Cooks

Noll

2008

406

290

Since its introduction, the orbitrap has proven to be a robust mass analyzer that can routinely deliver high resolving power and mass accuracy. Unlike conventional ion traps such as the Paul and Penning traps, the orbitrap uses only electrostatic fields to confine and to analyze injected ion populations. In addition, its relatively low cost, simple design and high space‐charge capacity make it suitable for tackling complex scientific problems in which high performance is required. This review begins with a brief account of the set of inventions that led to the orbitrap, followed by a qualitative description of ion capture, ion motion in the trap and modes of detection. Various orbitrap instruments, including the commercially available linear ion trap–orbitrap hybrid mass spectrometers, are also discussed with emphasis on the different methods used to inject ions into the trap. Figures of merit such as resolving power, mass accuracy, dynamic range and sensitivity of each type of instrument are compared. In addition, experimental techniques that allow mass‐selective manipulation of the motion of confined ions and their potential application in tandem mass spectrometry in the orbitrap are described. Finally, some specific applications are reviewed to illustrate the performance and versatility of the orbitrap mass spectrometers. © 2008 Wiley Periodicals, Inc., Mass Spec Rev 27: 661–699, 2008

“…Initial work to increase the MMA involved the use of "lock masses" (i.e., confidently known species that serve as effective FTICR-MS internal calibrants) for each spectrum. More recently, improved methods for introducing calibrant ions into each spectrum have increased the overall MMA to ∼2 ppm (Flora, et al, 2001, Tang, et al, 2002. Improving upon these methods will lead to routine measurements of <1 ppm mass accuracy in a high throughput fashion.…”

Section: Increased Mass Measurement Accuracy (Mma)mentioning

confidence: 99%

Advances in proteomics data analysis and display using an accurate mass and time tag approach

Zimmer

Monroe

Qian

et al. 2006

293

362

Proteomics has recently demonstrated utility in understanding cellular processes on the molecular level as a component of systems biology approaches and for identifying potential biomarkers of various disease states. The large amount of data generated by utilizing high efficiency (e.g., chromatographic) separations coupled to high mass accuracy mass spectrometry for high-throughput proteomics analyses presents challenges related to data processing, analysis, and display. This review focuses on recent advances in nanoLC-FTICR-MS-based proteomics approaches and the accompanying data processing tools that have been developed to display and interpret the large volumes of data being produced.