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Standing K.G.,University of Manitoba | Vestal M.L.,SimulTOF Systems
International Journal of Mass Spectrometry | Year: 2015

World War II electronic advances suggested the use of time-of-flight for mass measurements, leading to the development of a commercial TOFMS instrument by Bendix. This instrument used electron impact ionization, but the subsequent application of fission fragment bombardment (PDMS), coupled to TOFMS, was responsible for significant advances in the mass spectrometry of large biomolecules. Bombardment by accelerated MeV or keV ions, again coupled to TOFMS, was found to be equally successful. Although these TOF methods were the only ones initially capable of measuring the masses of really large biomolecules, most mass spectrometrists were still wedded to sector/quadrupole instruments for high/low-end mass measurements. The "coup de grace" for TOF (as generally believed) was the discovery ofasuitable matrix (glycerol), which enabled the useofsector/quadrupole instruments for measurements of large biomolecules ("fabulous FAB"). Ironically, it was the discovery of suitable matrices for laser excitation that revived TOFMS, aided by the additional accuracy provided by the reflecting geometry, and the subsequent development of orthogonal injection, as well as the coupling to liquid chromatography. Enormous technical advances in TOF were driven bythe invention of MALDI and facilitatedby the parallel advances in digital electronics. All of mass spectrometry has benefitted from these technical advances, but TOF most of all because of the need for high speed acquisition and large data storage capacity. Thus TOF is now in the mainstream of biological applications of mass spectrometry. © 2014 Published by Elsevier B.V.

Duncan M.W.,University of Colorado at Denver | Duncan M.W.,King Saud University | Nedelkov D.,Arizona State University | Walsh R.,University of Colorado at Denver | Hattan S.J.,SimulTOF Systems
Clinical Chemistry | Year: 2016

BACKGROUND: MALDI-TOF mass spectrometry (MS) is set to make inroads into clinical chemistry because it offers advantages over other analytical platforms. These advantages include low acquisition and operating costs, ease of use, ruggedness, and high throughput. When coupled with innovative front-end strategies and applied to important clinical problems, it can deliver rapid, sensitive, and cost-effective assays. CONTENT: This review describes the general principles of MALDI-TOF MS, highlights the unique features of the platform, and discusses some practical methods based upon it. There is substantial potential for MALDI-TOF MS to make further inroads into clinical chemistry because of the selectivity of mass detection and its ability to independently quantify proteoforms. SUMMARY: MALDI-TOF MS has already transformed the practice of clinical microbiology and this review illustrates how and why it is now set to play an increasingly important role in in vitro diagnostics in particular, and clinical chemistry in general. © 2015 American Association for Clinical Chemistry.

Hattan S.J.,SimulTOF Systems | Parker K.C.,SimulTOF Systems | Vestal M.L.,SimulTOF Systems | Yang J.Y.,University of California at San Diego | And 2 more authors.
Journal of the American Society for Mass Spectrometry | Year: 2016

Measurement of glycated hemoglobin is widely used for the diagnosis and monitoring of diabetes mellitus. Matrix assisted laser desorption/ionization (MALDI) time of flight (TOF) mass spectrometry (MS) analysis of patient samples is used to demonstrate a method for quantitation of total glycation on the β-subunit of hemoglobin. The approach is accurate and calibrated with commercially available reference materials. Measurements were linear (R2 > 0.99) across the clinically relevant range of 4% to 20% glycation with coefficients of variation of ≤ 2.5%. Additional and independent measurements of glycation of the α-subunit of hemoglobin are used to validate β-subunit glycation measurements and distinguish hemoglobin variants. Results obtained by MALDI-TOF MS were compared with those obtained in a clinical laboratory using validated HPLC methodology. MALDI-TOF MS sample preparation was minimal and analysis times were rapid making the method an attractive alternative to methodologies currently in practice. © 2016 American Society for Mass Spectrometry.

Zavalin A.,Vanderbilt University | Yang J.,Vanderbilt University | Hayden K.,SimulTOF Systems | Vestal M.,SimulTOF Systems | Caprioli R.M.,Vanderbilt University
Analytical and Bioanalytical Chemistry | Year: 2015

We have achieved protein imaging mass spectrometry capabilities at sub-cellular spatial resolution and at high acquisition speed by integrating a transmission geometry ion source with time of flight mass spectrometry. The transmission geometry principle allowed us to achieve a 1-μm laser spot diameter on target. A minimal raster step size of the instrument was 2.5 μm. Use of 2,5-dihydroxyacetophenone robotically sprayed on top of a tissue sample as a matrix together with additional sample preparation steps resulted in single pixel mass spectra from mouse cerebellum tissue sections having more than 20 peaks in a range 3–22 kDa. Mass spectrometry images were acquired in a standard step raster microprobe mode at 5 pixels/s and in a continuous raster mode at 40 pixels/s. © 2015 Springer-Verlag Berlin Heidelberg

Hattan S.J.,SimulTOF Systems | Du J.,Toxikon Corporation | Parker K.C.,SimulTOF Systems
Analytical Chemistry | Year: 2015

We describe the construction and characterization of a novel membrane designed to allow proteins separated by gel electrophoresis (SDS-PAGE) to be detected as peptides by mass spectrometry in an efficient and comprehensive manner. The key attribute of the membrane is a bifunctional design that allows for the digestion of protein(s) and retention of the resulting peptides with minimal lateral diffusion. Silane chemistries are used to differentially treat the opposing surfaces of a glass filter paper to enable this unique capability. (Figure Presented). © 2015 American Chemical Society.

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