Ionization region, mass spectrometry

Fig. 2 (a) The optical image of a rat brain from a coronal section, (b) Matrix-assisted laser desorp-tion/ionization (MALDI)-mass spectrometry (MS)/MS images of astemizole in the rat brain slice without perfusion and (c) with perfusion cortex, hippocampus, corpus callosum, hypothalamic region, thalamus region, choroid plexus, dorsal third ventricle, and lateral ventricle are indicated by arrows, (d) MALDI-MS/MS images of M-14 metabolite of astemizole in the rat brain slice (Li et al. [152], Reproduced with permission from Future Science Ltd)... 

Figure 1 Schematic diagram of a double-focusing field ionization mass spectrometer of conventional geometry (not drawn to scale), showing the four regions in which field ionization kinetic measurements can be made. The stated times refer to an ion source with a blade emitter. Reproduced with permission of Wiley from Nibbering NMM (1984) Mechanistic studies by field ionization kinetics. Mass Spectrometry Reviews Z 445-477.

The laser desorption experiments which we describe here utilize pulsed laser radiation, which is partially absorbed by the metal substrate, to generate a temperature jump in the surface region of the sample. The neutral species desorbed are ionized and detected by Fourier transform mass spectrometry (FTMS). This technique has... 

Coupling of liquid chromatography to mass spectrometry has not only led to a wide variety of interfaces, but also initiated the development of new ionization methods. [8-13,62] In retrospect, the moving belt interface seems rather a curiosity than a LC-interface. The LC effluent is deposited onto a metal wire or belt which is heated thereafter to desolvate the sample. Then, the belt traverses a region of... 

Muller, C., Schafer, P., Stortzel, M., Vogt, S., and Weinmann, W. (2002). Ion suppression effects in liquid chromatography-electrospray-ionization transport-region collision induced dissociation mass spectrometry with different serum extraction methods for systematic toxicological analysis with mass spectra libraries. /. Chromatogr. B 773, 47— 52. 

In order for mass spectrometry to be used as an effective tool in LC, the analyte must be ionized in the interface region (source) since MS can only detect charged species. Consequently, the role of the ionization source is twofold (1) it is responsible for interfacing the chromatographic instrument with the detector and (2) it provides an effective and efficient means for sample ionization. It should be pointed out that source ionization efficiency plays a significant role in sample sensitivity for LC-MS analysis. The application of LC is ideally... 

Knop, G., and F. Arnold, Atmospheric Acetonitrile Measurements in the Tropopause Region Using Aircraft-Borne Active Chemical Ionization Mass Spectrometry, Planet. Space Sci., 35, 259-266 (1987b). 

Mass spectrometry (MS) is now an integrated detector for liquid chromatography. This is due to the advent of atmospheric pressure ionization (API) interfaces. In an API interface, the column effluent is nebulized into an atmospheric pressure ion region. Nebulization is performed pneumatically in atmospheric pressure chemical ionization (APCI) by a strong electrical field in electrospray or by a combination of both in ion spray. Ions are produced from the evaporating droplets... 

---