Fast atom bombardment mass aqueous solutions

Analysis of Reactions in Aqueous Solution Using Fast Atom Bombardment Mass Spectrometry... 

Fast atom bombardment mass spectrometry has been utilized for the quantitative determination of ionic species, in glycerol/water solutions, which are produced by chemical and enzymic reactions. It is shown that reaction constants can be determined in this manner and that they can be accurately related to those determined by other methods used in the analysis of aqueous solutions. The reactions studied include proton dissociation constants for organic acids, an enzyme equilibrium constant, and enzyme rate constants using natural substrates. 

Fast atom bombardment mass spectrometry (FABMS) has become an important addition to the ionization techniques available to the analytical chemist in recent years. It has been particularly useful in a number of diverse applications which include molecular weight determinations at high mass, peptide and oligosaccharide sequencing, structural analysis of organic compounds, determination of salts and metal complexes, and the analysis of ionic species in aqueous solutions. This paper will focus on some aspects of the quantitative measurement of ionic species in solution. The reader is referred to a more comprehensive review for more details of some of the examples given here as well as other applications (1). 

More recently, studies concerning cluster ion formation from solid or deeply cooled liquid alcohols [120-122] have gained new interest. [123,124] Low-temperature fast atom bombardment (LT-FAB) of frozen aqueous solutions of metal salts provides a source of abundant hydrated metal ions. [125-127] Organic molecules can also be detected from their frozen solutions. [128] Such LT-FAB applications are particularly interesting when enabling the detection of species that would otherwise not be accessible by mass spectrometry, because they are either extremely air- and/or water-sensitive [129,130] as the phosphaoxetane intermediate of the Wittig reaction [131] or insoluble in standard FAB matrices. [106,132]... 

In the 1980s, attempts were made to enable continuous introduction of liquid samples (especially aqueous buffer solutions) to ion sources of mass spectrometers. An early con-tiuous flow interface was based on the fast atom bombardment (FAB) ion source [70]. However, it was the ESI interface that greatly facilitated temporal profiling of dynamic... 

A modification of the FAB technique is continuous flow FAB (CFFAB). In this approach, the sample in solution is introduced into the mass spectrometer through a fused silica capillary. The tip of the capillary is the target. The solution is bombarded by fast atoms produced as described earlier. Solvent is flowing continuously and the liquid sample is introduced by continuous flow injection (Fig. 9.13). The mass spectrum produced has the same characteristics as that from conventional FAB, but with low background. Typically, the solvent used is 95% water and 5% glycerol. The ability to inject aqueous samples is an enormous advantage in biological and environmental studies. 

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