Mass resolution improvements

Brown, R. S. Lennon, J. J. Mass resolution improvement by incorporation of pulsed ion extraction in a matrix-assisted laser desorption/ionization linear time-of-flight mass spectrometer. Anal. Chem. 1995,67,1998-2003. 

R. S. Brown and J. J. Lennon. Mass Resolution Improvement by Incorporation of Pulsed Ion Extraction in a Matrix-Assisted Laser Desorption/Ionization Linear Time-of-Flight Mass Spectrometer. Anal. Chem., 67(1995) 1998-2003. 

Bahr, U., StahlZeng, J., Gleitsmann, E. and Karas, M., Delayed extraction time-of-flightMALDI mass spectrometry of proteins above 25,000 Da. J. Mass Spectrom., 32, 1111-1116 (1997). Brown, R.S. and Lennon, J.J., Mass resolution improvement by incorporation of pulsed ion extraction in a matrix-assisted laser-desorption ionization linear time-of-flight mass-spectrometer. AwaZ. Chem., 67, 1998-2003 (1995). 

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. 

The reflectron increases the spatial separation of the ions of different m/z values by making them travel up and down the flight tube, so the distance traveled is twice what it would be if the ions simply passed once along the tube from one end to the other. The reflectron also narrows the energy spread for individual m/z values, thus improving mass resolution. TOP analyzers are not necessarily equipped with a reflectron. 

State-of-the-art ToF-MS employs reflection lenses and delayed extraction [176] to improve resolution by minimising small differences in ion energies, and in these cases up to 12000 mass resolution (FWHM, m/z 600) is available. This is sufficient for most modern applications. Solid probe ToF-MS (or direct inlet high-resolution mass spectrometry, DI-HRMS) is a breakthrough. DIP-ToFMS is a thermal separation technique. Advantages of DIP-ToFMS are ... 

Lasers have advanced the analytical use of mass spectrometers to characterise additives in polymers, and routine application of MALDI is no longer limited to high molecular masses only. MALDI can now clearly produce isotopically resolved mass spectra of small molecules (<800 Da) in an L-ToF instrument, which can be used successfully for the characterisation of molecules of different chemical classes. High mass resolution with an improvement of mass accuracy to... 

The ECAP incorporates an electrostatic lens in the time-of-flight spectrometer in order to improve the mass resolution by compensating for small spreads in the energies of the ions evaporated from the specimen under the pulsed electric field. A lens design by Poschenrieder or a reflectron type of electrostatic lens is used for this purpose, and is standard equipment for metallurgical or materials applications of APFIM. These typically improve the mass resolution at full width half maximum (FWHM) from m/Am 250 to better than 2000. 

Triterpenoid resins used as varnishes on paintings were first studied with GALDI-MS by Zumbiihl et al. [3,4], He realised that freshly bought commercial resin, usually considered fresh , is actually in an advanced stage of oxidation. Additional experiments were performed later on with improved mass resolution that allowed more detailed conclusions [34 36],... 

Columns filled with polymer solutions are extremely simple to prepare, and the packing can easily be replaced as often as desired. These characteristics make the pseudostationary phases excellent candidates for use in routine CEC separations such as quality control applications where analysis and sample profiles do not change much. However, several limitations constrain their widespread use. For example, the sample capacity is typically very low, pushing typical detection methods close to their sensitivity limits. Additionally, the migration of the pseudostationary phase itself may represent a serious problem, e. g., for separations utilizing mass spectrometric detection. The resolution improves with the concentration of the pseudostationary phase. However, the relatively low solubility of current amphiphilic polymers does not enable finding the ultimate resolution limits of these separation media [88]. 

Higher mass resolution is becoming more common in MC-ICPMS technology. The result will be a reduction in the hindrances of isobaric interferences. With judicious use of narrow entrance slits and improvements in ion optics, even smaller radius instruments can resolve 50Ti from Mg+, for example. However, at this writing most studies have made use of low-mass-resolution instruments, and even with high mass resolution, care must still be taken to avoid changes in instrumental fractionation due the presence of elements other than the analyte in the plasma. 

Thomson, B.A. Douglas, D.J. Corr, J.J. Hager, J.W. Jolliffe, C.E. Improved CID Efficiency and Mass Resolution on a Triple Quadrupole Mass Spectrometer. Anal Chem. 1995, 67, 1696-1704. 

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