Relative mass resolution

Both the time and the space domain show field free (white) areas with respect to the actual potentials. In the time domain these effects emerge during switching. In the space domain the electric field in the gaps between the finger electrodes cannot be controlled fully. This is the main reason for some blurr in the filter process. The relative mass resolution can be approximated as ... 

While the relative mass resolution of ca 10 of the SCSl-MS technique can compete very well with standard QMF and TOF mass spectrometers, the mass accuracy of the SCSI-MS technique will probably never be able to challenge that of FT-ICR mass spectrometry nevertheless, this shortcoming does not mean that the new technique is irrelevant. On the contrary, the SCSI-MS technique encompasses the advantages of high spatial and tanporal resolution from QMF and TOF together with the ability to perform non-destructive detection from FT-ICR. 

Although ion transmission guides and ion traps both use the same universal physical laws to achieve control over ion behavior, the ways in which the laws are used are different, as are the objectives. The guides do not retain ions to gain control over their velocities and are used simply to transmit both slow and fast ions over a very wide range of gas pressures. Ion traps retain ions over a relatively long period of time so as to adjust their kinetic energies and thereby improve mass resolution. The so-called bath gas is used at carefully controlled pressures. 

Qualitatively, the spark source mass spectrum is relatively simple and easy to interpret. Most instrumentation has been designed to operate with a mass resolution Al/dM of about 1500. For example, at mass M= 60 a difference of 0.04 amu can be resolved. This is sufficient for the separation of most hydrocarbons from metals of the same nominal mass and for precise mass determinations to identify most species. Each exposure, as described earlier and shown in Figure 2, covers the mass range from Be to U, with the elemental isotopic patterns clearly resolved for positive identification. 

In other experiments, PVC/plasticiser extracts (n-hexane) were separated by SEC using THF or chloroform as the mobile phase. Similarly, PE film was immersed in THF for several hours and the extract was concentrated by a factor of 20 prior to injection into a SEC system [51]. However, use of extraction techniques followed by injection into a SEC system for separation of low-MW additives is not the most obvious analytical approach in view of the relatively low resolution of conventional SEC in the low molecular mass range. For this purpose efficient column packing materials with small pore sizes are to be used. 

One typical example of carbon/carbon composite plates is that made by Oak Ridge National Laboratory (ORNL) in the United States [12]. The composite preform was fabricafed by a slurry-molding process from fhe mixed slurry befween short carbon fibers (graphite fibers were also added in some sample plates) and fhe phenolic resin. The mass rafio between fiber reinforcement and phenolic matrix is 4 3. The phenolic matrix improves the mechanical properties and dimensional stability of the plate. A subsequent vacuum molding process was utilized to fabricate composite plates and fluid fields with relatively high resolution (Figure 5.3, [11]). 

With soft ionization techniques such as MALDI, ions of m/z 200000 can be routinely detected. The mass range is mainly limited by the fact that with the detector the response decreases with increasing m/z of the ions. The mass resolution of a TOF mass analyzer is relatively poor (unit mass resolution and less) and is affected by factors that create a distribution in the flight time of ions with the same m/z. The simplest way to increase the mass resolution is to increase the length of flight tube or to reduce the kinetic energy spread of the ions leaving the source. 

Quantitative Bioanalysis with High Mass Resolution Prior to the introduction of the API sources for LC-MS, GC-MS was the dominant format for mass spectrometry. Within GC-MS, mass analysis at high resolution using magnetic sector instruments was relatively common, especially in the central mass spectrometry facilities of major corporations and universities. Uses of these instruments included quantitation by GC-HRMS for improved specificity and sensitivity. 

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