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High mass

OF High-Molecular-Weight Samples 1. Definition of High Mass [Pg.34]

Ten years ago, it was easy to give a working definition of high mass. At that time, most mass spectrometers had a mass range of less than 1000 at [Pg.34]

There are three main reasons for this choice. Firstly, it becomes more and more difficult to obtain recordable, molecular-ion signals from un-derivatized carbohydrates as their M, increases significantly above 3000. Secondly, the mass spectrometers that have been used in all high-mass-carbofiydrate studies published at the time of writing this article are not capable of very sensitive analysis above —3800 mass units (see later). Thirdly, at masses 4000, it is usually not practicable to work at the resolution necessary for adjacent peaks to appear as separate signals in the spectrum. To do so would require that the source and collector slits be narrowed to such a degree that there would be an unacceptable loss in sensitivity. Thus, spectra acquired at mass 4000 are usually composed of unresolved clusters. [Pg.36]

Operation of the high-field ZAB spectrometer at 7-kV accelerating voltage extends the mass range to nearly 3800 without a significant loss in sensitivity. Above that point, there is a steady decline in sensitivity. When V is lessened [Pg.36]


Laser desorption methods are particularly useful for substances of high mass such as natural and synthetic polymers. Glycosides, proteins, large peptides, enzymes, paints, ceramics, bone, and large... [Pg.11]

On the other hand, there are some ionization techniques that are very useful, particularly at very high mass, but produce ions only in pulses. For these sources, the ion extraction field can be left on continuously. Two prominent examples are Californium radionuclide and laser desorption ionization. In the former, nuclear disintegration occurs within a very short time frame to give a... [Pg.192]

Peak matching can be done on quadrupole and magnetic-sector mass spectrometers, but only the latter, particularly as double-focusing instruments, have sufficiently high resolution for the technique to be useful at high mass. [Pg.274]

The techniques described thus far cope well with samples up to 10 kDa. Molecular mass determinations on peptides can be used to identify modifications occurring after the protein has been assembled according to its DNA code (post-translation), to map a protein structure, or simply to confirm the composition of a peptide. For samples with molecular masses in excess of 10 kDa, the sensitivity of FAB is quite low, and such analyses are far from routine. Two new developments have extended the scope of mass spectrometry even further to the analysis of peptides and proteins of high mass. [Pg.290]

When multicharged ions are formed, the simple rule of thumb used widely in mass spectrometry that m/z = m because, usually, z = 1 no longer applies for z > 1 then m/z < m, and the apparent mass of an ion is much smaller than its true mass. Accurate mass measurement is much easier at low mass than at high, and the small m/z values, corresponding to high mass with multiple charges, yield accurate values for the high mass. [Pg.390]

For very high mass, when sensitivity is frequently critical, the reflectron is not used and lower resolution is accepted. [Pg.406]

After acceleration through an electric field, ions pass (drift) along a straight length of analyzer under vacuum and reach a detector after a time that depends on the square root of their m/z values. The mass spectrum is a record of the abundances of ions and the times (converted to m/z) they have taken to traverse the analyzer. TOP mass spectrometry is valuable for its fast response time, especially for substances of high mass that have been ionized or selected in pulses. [Pg.407]

Delayed Proton and Neutron Decays. By means of a variety of nuclear reactions, as weh as the spontaneous fission of synthetic nucHdes, large numbers of isotopes of some elements have been produced. For example, whereas the only stable isotope of Cs (Z = 55) is Cs (JV = 78), ah of the Cs isotopes from Cs where 77 = 59 and = 0.57 s, to Cs where N = 93 and = 0.13 s, have been observed. At the low mass end of this series, the last proton is only loosely bound, and at the high mass end, the last neutron is only loosely bound. [Pg.451]

Leveque s approximation Concentration BL is thin. Assume velocity profile is linear. High mass velocity. Fits liquid data well. [Pg.608]

High mass-transfer rates in both vapor and hquid phases. Close approach to eqiiilihriiim. Adiabatic contact assures phase eqiiilihriiim, Only moderate mass-transfer rate in liquid phase, zero in sohd. Slow approach to equilibrium achieved in brief contact time. Included impurities cannot diffuse out of solid. Sohd phase must be remelted and refrozen to allow phase equilibrium. [Pg.1989]

High mass resolution techniques are used to separate peaks at the same nominal mass by the very small mass differences between them. As an example, a combination of Si and H to form the molecular ion Si H , severely degrades the detection limit of phosphorous ( P) in a silicon sample. The exact mass of phosphorous ( P) is 31.9738 amu while the real masses of the interfering Si H and Si H2 molecules are 31.9816 amu and 31.9921 amu, respectively. Figure 8 shows a mass... [Pg.543]

SiiH2 are completely separated from the peak. Quadrupole instruments are not usually capable of such high mass resolution. [Pg.544]

Figures High mass resoiution mass spectrum obtained from a phosphorus-doped amorphous silicon hydride thin film using a magnetic sector ion microanalyzer. The peak is well separated from the hydride iirterferences. Figures High mass resoiution mass spectrum obtained from a phosphorus-doped amorphous silicon hydride thin film using a magnetic sector ion microanalyzer. The peak is well separated from the hydride iirterferences.
The choice of mass spectrometer for a particular analysis depends on the namre of the sample and the desired results. For low detection limits, high mass resolution, or stigmatic imaging, a magnetic sector-based instrument should be used. The analysis of dielectric materials (in many cases) or a need for ultrahigh depth resolution requires the use of a quadrupole instrument. [Pg.548]

Figure 3.5 shows the positive SSIMS spectrum from a silicon wafer, illustrating both the allocation of peaks and potential isobaric problems. SSIMS reveals many impurities on the surface, particularly hydrocarbons, for which it is especially sensitive. The spectrum also demonstrates reduction of isobaric interference by high-mass resolution. For reasons discussed in Sect. 3.1.3, the peak heights cannot be taken to be directly proportional to the concentrations on the surface, and standards must be used to quantify trace elements. [Pg.94]


See other pages where High mass is mentioned: [Pg.86]    [Pg.186]    [Pg.209]    [Pg.288]    [Pg.2]    [Pg.386]    [Pg.42]    [Pg.541]    [Pg.541]    [Pg.549]    [Pg.191]    [Pg.518]    [Pg.408]    [Pg.171]    [Pg.2115]    [Pg.2181]    [Pg.2394]    [Pg.23]    [Pg.181]    [Pg.749]    [Pg.184]    [Pg.186]    [Pg.186]    [Pg.474]    [Pg.522]    [Pg.523]    [Pg.543]    [Pg.544]    [Pg.547]    [Pg.552]    [Pg.552]    [Pg.552]    [Pg.563]    [Pg.612]    [Pg.612]    [Pg.622]   


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Accelerator mass spectrometry high energy analysis

Animal studies high-resolution mass spectrometry

Applied High-Resolution Mass Spectrometry

Atomic composition can be determined by high-resolution mass spectrometry

Batch-mass reactors high conversion

Coupled with high pressure mass

Direct inlet -high-resolution mass spectrometry

Electrospray ionization high-mass capabilities

Exact Mass Measurements (High Resolution)

Fast atom bombardment high-mass analytes

Fast-atom bombardment high-resolution mass

Filters/filtering high-resolution mass spectrometry

Fractures high temperature rock mass

Fragmentation high-resolution mass spectrometry

Gas chromatography-high resolution mass spectrometry

High Resolution Accurate Mass MID Data Acquisition

High Resolution Mass Spectrometry HR-MS)

High accelerated mass spectrometry

High electrospray ionization mass

High glow discharge mass spectrometry

High mass accelerator

High mass accuracy analyzers

High mass pass filter

High mass resolution requirements

High mass sensitive

High mass spectra

High mass spectrometry

High mass transfer processes

High mass transport

High molar mass birch lignosulfonates

High molar mass samples

High molecular mass copolyesters

High molecular mass kininogen

High performance liquid capillary electrophoresis- mass

High performance liquid chromatography combined with mass spectrometry (

High performance liquid chromatography coupled with tandem mass

High performance liquid chromatography mass spectrometer

High performance liquid chromatography mass transfer

High performance liquid chromatography with tandem mass

High performance liquid chromatography with tandem mass spectrometry , determination

High performance liquid chromatography/atmospheric pressure ionization-mass spectrometry

High performance liquid chromatography/atmospheric pressure ionization-tandem mass spectrometry

High performance liquid chromatography/mass

High performance liquid chromatography/mass matrix effects

High performance liquid chromatography/mass spectrometry

High performance liquid inductively coupled plasma-mass

High performance liquid ionization-mass spectroscopy

High performance liquid mass analyzers

High precision mass

High pressure chromatography-coupled mass

High pressure chromatography-coupled mass spectrometry

High pressure liquid chromatography-mass

High pressure liquid chromatography-mass spectrometry

High pressure mass

High pressure mass spectrometry HPMS)

High resolution ICP mass spectra

High resolution fast-atom-bombardment mass spectrometry

High resolution field desorption mass spectroscopy

High resolution mass analysis

High resolution mass spectrometr

High resolution mass spectrometry

High resolution mass spectrometry organic chemistry

High resolution mass spectrometry system

High resolution sector mass spectrometers

High resolution separation column Chromatography Mass Spectroscopy in Polymer Analysis

High resolution separation column Mass detection

High resolution separation column Mass spectroscopy

High resolution triple quadrupole mass

High resolution triple quadrupole mass spectrometers

High solid probe mass spectrometry

High tandem mass spectrometry

High temperature gas chromatography mass

High temperature gas chromatography mass spectrometry

High temperature mass spectrometer

High temperature rock mass

High with mass spectrometric detection

High-Mass Analytes in FAB-MS

High-Pressure Mass Spectrometiy

High-Resolution Mass Spectrometry Can Reveal Molecular Formulas

High-Resolution and Accurate Mass

High-Resolution, Accurate Mass Measurement Elemental Compositions

High-Throughput Microbial Characterizations Using Electrospray Ionization Mass Spectrometry and Its Role in Functional Genomics

High-accuracy mass measurement (

High-field asymmetric waveform ion mobility mass

High-field asymmetric waveform ion mobility mass spectrometry

High-mass clusters

High-mass definition

High-mass instrumentation

High-mass ions, resolution

High-mass practical aspects

High-molar-mass polymer systems

High-molecular-mass molecules

High-performance liquid chromatography HPLC), with mass spectrometr

High-performance liquid chromatography coupled mass spectrometry

High-performance liquid chromatography mass spectroscopy

High-performance liquid chromatography tandem mass

High-performance liquid chromatography tandem mass spectrometry

High-performance liquid chromatography with mass spectrometry

High-performance liquid chromatography with nuclear magnetic resonance-mass

High-performance liquid chromatography with ultraviolet-mass spectrometry

High-performance liquid chromatography-inductively coupled plasma mass

High-performance liquid chromatography-inductively coupled plasma mass spectrometry

High-performance liquid chromatography-mass spectrometry HPLC-MS)

High-performance liquid ionization-tandem mass

High-performance liquid mass spectrometry

High-pressure mass spectrometers

High-pressure mass spectrometers HPMS)

High-pressure mass spectrometry

High-resolution (a) raw data spectrum and (b) accurate masses calculated from internal calibration table

High-resolution double focusing mass

High-resolution double focusing mass spectrometer

High-resolution electron impact mass

High-resolution electron impact mass spectrometry

High-resolution inductively coupled plasma mass spectrometry

High-resolution mass

High-resolution mass spectrometer HRMS)

High-resolution mass spectrometers

High-resolution mass spectrometry HRMS)

High-resolution mass spectrometry Orbitrap

High-resolution mass spectrometry environmental applications

High-resolution mass spectrum HRMS)

High-resolution mass values

High-resolution scans liquid chromatography mass

High-resolution scans mass spectrometers

High-resolution scans mass spectrometry

High-resolution tandem mass spectrometry

High-resolution tandem mass spectrometry HRMS)

High-resolution time-of-flight mass

High-resolution time-of-flight mass spectrometry

High-resolving mass analyzers

High-shear interface mass transfer coefficient

High-temperature gases mass change analysis

High-throughput affinity selection-mass spectrometry

High-throughput screening mass spectrometry applications

Highly isotope masses

Isolation high resolution mass spectrometry

Liquid chromatography-high-resolution mass spectrometry

Liquid chromatography-mass spectrometry high polarity

Liquid high molar mass

Low-Temperature Calorimetric Detectors for High-Mass Ions

Mass Spectrometry ultra-high-resolution

Mass Transfer at Moderate and High Reynolds Numbers

Mass analysis high-sensitivity

Mass analyzers, high-resolution

Mass change analysis, high-temperature

Mass measurement, high-resolution, accurate

Mass pulsed-electron high-pressure

Mass spectrometer high-voltage, double-focusing, sector

Mass spectrometer, high-resolution double

Mass spectrometers high-resolution studies

Mass spectrometry high resolution technique

Mass spectrometry with high-performance liquid

Mass spectroscopy high-resolution

Mass spectrum high-resolution

Mass transfer high flux, effect

Mass ultra-high

Molecular formula, by high resolution mass

Molecular formula, from high-resolution mass spectrometry

Multiple high resolution mass

Neutral loss high-resolution mass spectrometry

Particle beam high-performance liquid chromatography/mass spectrometry

Permethylated, High-Mass Samples

Polyethylene ultra-high molar mass

Polymer high-molecular mass

Practical Aspects of Analysis at High Mass

Pulsed high-pressure mass

Pulsed high-pressure mass spectrometry

Pulsed high-pressure mass spectrometry PHPMS)

Pyrolysis high-resolution mass spectrometry

Reaction Mechanisms with Highly Reactive Gases and Discrimination by Selective Bandpass Mass Filtering

Relatively Very High Mass Transfer Rates

Sector high mass resolution with

Selectivity analysis high-resolution mass spectrometry

Sensitivity analysis high-resolution mass spectrometry

Single high mass resolution with sector field

Specificity analysis high-resolution mass spectrometry

Spectral high mass resolution with sector field

Structural high resolution mass spectrometry

Synapt high definition mass spectrometer

Water-soluble high molar mass polymer

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