NOTE ON THE RESOLVING POWER OF MASS SPECTROMETERS

1952 ◽  
Vol 30 (5) ◽  
pp. 503-511 ◽  
Author(s):  
Larkin Kerwin
Keyword(s):  
Mass Spectrometer ◽  
Beam Width ◽  
Resolving Power ◽  
Homogeneous Field ◽  
Current Interest ◽  
Field Mass ◽  
Mass Spectrometers

In calculating the resolving power of a homogeneous field mass spectrometer, one must consider the dispersion and the beam width of the instrument. The latter is the sum of at least 10 components, which are discussed. Formulae giving the resolving power of three types of spectrometer of current interest are developed, as well as formulae for positioning the exit slits.

scholarly journals Quadrupole Ion Trap Mass Spectrometer for Ice Giant Atmospheres Exploration

2021 ◽  
Vol 217 (1) ◽  
Author(s):  
J. Simcic ◽  
D. Nikolić ◽  
A. Belousov ◽  
D. Atkinson ◽  
C. Lee ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Ion Trap ◽  
Quadrupole Ion Trap ◽  
Atomic Mass ◽  
Charge Ratio ◽  
Inlet System ◽  
Mass Spectrometers ◽  
Ion Trap Mass Spectrometer ◽  
Entry Probe ◽  
Composition Measurements

AbstractTo date, a variety of different types of mass spectrometers have been utilized on missions to study the composition of atmospheres of solar system bodies, including Venus, Mars, Jupiter, Titan, the moon, and several comets. With the increasing interest in future small probe missions, mass spectrometers need to become even more versatile, lightweight, compact, and sensitive.For in situ exploration of ice giant atmospheres, the highest priority composition measurements are helium and the other noble gases, noble gas isotopes, including 3He/4He, and other key isotopes like D/H. Other important but lower priority composition measurements include abundances of volatiles C, N, S, and P; isotopes 13C/12C, 15N/14N, 18O/17O/16O; and disequilibrium species PH3, CO, AsH3, GeH4, and SiH4. Required measurement accuracies are largely defined by the accuracies achieved by the Galileo (Jupiter) probe Neutral Mass Spectrometer and Helium Abundance Detectors, and current measurement accuracies of solar abundances.An inherent challenge of planetary entry probe mass spectrometers is the introduction of material to be sampled (gas, solid, or liquid) into the instrument interior, which operates at a vacuum level. Atmospheric entry probe mass spectrometers typically require a specially designed sample inlet system, which ideally provides highly choked, nearly constant mass-flow intake over a large range of ambient pressures. An ice giant descent probe would have to operate for 1-2 hours over a range of atmospheric pressures, possibly covering 2 or more orders of magnitude, from the tropopause near 100 mbar to at least 10 bars, in an atmospheric layer of depth beneath the tropopause of about 120 km at Neptune and about 150 km at Uranus.The Jet Propulsion Laboratory’s Quadrupole Ion Trap Mass Spectrometer (QITMS) is being developed to achieve all of these requirements. A compact, wireless instrument with a mass of only 7.5 kg, and a volume of 7 liters (7U), the JPL QITMS is currently the smallest flight mass spectrometer available for possible use on planetary descent probes as well as small bodies, including comet landers and surface sample return missions. The QITMS is capable of making measurements of all required constituents in the mass range of 1–600 atomic mass units (u) at a typical speed of 50 mass spectra per second, with a sensitivity of up to $10^{13}$ 10 13  counts/mbar/sec and mass resolution of $m/\Delta m=18000$ m / Δ m = 18000 at m/q = 40. (Throughout this paper we use the unit of m/q = u/e for the mass-to-charge ratio, where atomic mass unit and elementary charge are $1~\text{u} = 1.66\times 10^{-27}~\text{kg}$ 1 u = 1.66 × 10 − 27 kg and $1\text{e} = 1.6\times 10^{-19}$ 1 e = 1.6 × 10 − 19 C, respectively.) The QITMS features a novel MEMS-based inlet system driven by a piezoelectric actuator that continuously regulates gas flow at inlet pressures of up to 100 bar.In this paper, we present an overview of the QITMS capabilities, including instrument design and characteristics of the inlet system, as well as the most recent results from laboratory measurements in different modes of operation, especially suitable for ice giant atmospheres exploration.

scholarly journals Mass Spectrometric Calibration Procedure for Real-Time Detection of Lighter Hydrocarbons

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2123
Author(s):  
Makuachukwu F. Mbaegbu ◽  
Puspa L. Adhikari ◽  
Ipsita Gupta ◽  
Mathew Rowe
Keyword(s):  
Real Time ◽  
Mass Spectrometer ◽  
Calibration Procedure ◽  
Mass Spectrometric ◽  
Spectrometric Method ◽  
Mass Selection ◽  
Mass Spectrometric Method ◽  
Mass Spectrometers ◽  
Drilling Rig

Determining gas compositions from live well fluids on a drilling rig is critical for real time formation evaluation. Development and utilization of a reliable mass spectrometric method to accurately characterize these live well fluids are always challenging due to lack of a robust and effectively selective instrument and procedure. The methods currently utilized need better calibration for the characterization of light hydrocarbons (C1–C6) at lower concentrations. The primary goal of this research is to develop and optimize a powerful and reliable analytical method to characterize live well fluid using a quadruple mass spectrometer (MS). The mass spectrometers currently being used in the field have issues with detection, spectra deconvolution, and quantification of analytes at lower concentrations (10–500 ppm), particularly for the lighter (<30 m/z) hydrocarbons. The objectives of the present study are thus to identify the detection issues, develop and optimize a better method, calibrate and QA/QC the MS, and validate the MS method in lab settings. In this study, we used two mass spectrometers to develop a selective and precise method to quantitatively analyze low level lighter analytes (C1–C6 hydrocarbons) with masses <75 m/z at concentrations 10–500 ppm. Our results suggest that proper mass selection like using base peaks with m/z 15, 26, 41, 43, 73, and 87, respectively, for methane, ethane, propane, butane, pentane, and hexane can help detect and accurately quantify hydrocarbons from gas streams. This optimized method in quadrupole mass spectrometer (QMS) will be invaluable for early characterization of the fluid components from a live hydrocarbon well in the field in real time.

scholarly journals Source and origin of atmospheric trace elements entrapped in winter snow of the Italian Eastern Alps

2006 ◽  
Vol 6 (5) ◽  
pp. 8781-8815 ◽  
Author(s):  
P. Gabrielli ◽  
G. Cozzi ◽  
S. Torcini ◽  
P. Cescon ◽  
C. Barbante
Keyword(s):  
Boundary Layer ◽  
Trace Elements ◽  
Mass Spectrometer ◽  
Inductively Coupled Plasma ◽  
Major Ions ◽  
Eastern Alps ◽  
Field Mass ◽  
Inductively Coupled ◽  
Winter Snow ◽  
Snow Samples

Abstract. Trace elements concentrations were determined in shallow snow samples from 21 sites in the Italian Eastern Alps in order to identify the sources of the contaminants present in the tropospheric winter boundary layer. The collection of superficial snow layers was carried out weekly at altitudes between 1000 and 3000 m next to meteorological stations, far away from villages, roads and ski slopes. Ultra clean procedures were adopted in order to avoid contamination of the snow during the different experimental phases. Trace elements (Ag, Ba, Bi, Cd, Co, Cr, Cu, Fe, Mo, Mn, Pb, Sb, Ti, U, V and Zn) were determined by Inductively Coupled Plasma Sector Field Mass Spectrometer (ICP-SFMS). Ancillary parameters such as major ions (SO42−, NO3−, Ca2+;, Mg2+, K

scholarly journals Limits for resolving tandem mass tag reporter ions with identical integer mass using phase constrained spectrum deconvolution

2018 ◽  
Author(s):  
Christian D. Kelstrup ◽  
Konstantin Aizikov ◽  
Tanveer S. Batth ◽  
Arne Kreutzman ◽  
Dmitry Grinfeld ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Peptide Sequencing ◽  
Mass Resolution ◽  
Resolving Power ◽  
Acquisition Time ◽  
Tandem Mass ◽  
Optimal Method ◽  
Orbitrap Mass Spectrometer ◽  
Mass Resolving Power ◽  
Spectrum Deconvolution

ABSTRACTA popular method for peptide quantification relies on isobaric labeling such as tandem mass tags (TMT) which enables multiplexed proteome analyses. Quantification is achieved by reporter ions generated by fragmentation in a tandem mass spectrometer. However, with higher degrees of multiplexing, the smaller mass differences between the reporter ions increase the mass resolving power requirements. This contrasts with faster peptide sequencing capabilities enabled by lowered mass resolution on Orbitrap instruments. It is therefore important to determine the mass resolution limits for highly multiplexed quantification when maximizing proteome depth. Here we defined the lower boundaries for resolving TMT reporter ions with 0.0063 Da mass differences using an ultra-high-field Orbitrap mass spectrometer. We found the optimal method depends on the relative ratio between closely spaced reporter ions and that 64 ms transient acquisition time provided sufficient resolving power for separating TMT reporter ions with absolute ratio changes up to 16-fold. Furthermore, a 32 ms transient processed with phase-constrained spectrum deconvolution provides >50% more identifications with >99% quantified, but with a slight loss in quantification precision and accuracy. These findings should guide decisions on what Orbitrap resolution settings to use in future proteomics experiments relying on TMT reporter ion quantification with identical integer masses.

scholarly journals Petroleomics via Orbitrap mass spectrometry with resolving power above 1 000 000 at m/z 200

RSC Advances ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 6183-6191 ◽  
Author(s):  
Eduardo M. Schmidt ◽  
Marcos A. Pudenzi ◽  
Jandyson M. Santos ◽  
Celio F. F. Angolini ◽  
Rosana C. L. Pereira ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Fourier Transform ◽  
Electrospray Ionization ◽  
Mass Spectrometer ◽  
High Field ◽  
Resolving Power ◽  
Fourier Transform Mass Spectrometer ◽  
Orbitrap Mass Spectrometry ◽  
Petroleum Sample ◽  
Sample Characterization

The performance of the high-field MegaOrbitrap Fourier transform mass spectrometer (FT-MS) with electrospray ionization (ESI) was evaluated to perform petroleum sample characterization via classical petroleomics approaches.

Correcting for the dynamic response of a respiratory mass spectrometer

1983 ◽  
Vol 55 (3) ◽  
pp. 1015-1022 ◽  
Author(s):  
J. H. Bates ◽  
G. K. Prisk ◽  
T. E. Tanner ◽  
A. E. McKinnon
Keyword(s):  
Time Delay ◽  
Mass Spectrometer ◽  
Wiener Filter ◽  
Simulated Data ◽  
Exponential Model ◽  
Transform Method ◽  
Mass Spectrometers ◽  
Model Method ◽  
Order Of Magnitude ◽  
Delay Correction

Mass spectrometers produce distorted measurements of gas concentrations because of the time delays and rise times inherent in their responses. Three techniques for numerically correcting such distortion were applied to the acetylene step responses of a Perkin-Elmer MGA1100 mass spectrometer and to simulated data. The techniques investigated were 1) a simple time-delay correction, 2) an exponential model method that assumes a biexponential form for the peak of the impulse response, and 3) a Fourier transform method of deconvolution known as Wiener filtering. The time-delay correction produced an order of magnitude reduction in measurement error. The exponential model method improved on the time-delay correction, and the Wiener filter gave the most accurate corrections in all cases examined.

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