Electrospray interface disadvantages

In all these application areas, Cf-FAB has almost completely lost territory to electrospray interfaces. The two most important disadvantages of Cf-FAB are the limitations in the maximum allowable flow-rate and the difficulty of achieving stable conditions by balancing the solvent flow-rate, viscosity and surface tension, and the temperature, wettability, and liquid-film properties of the target. Because of its easy implementation on sector instmment, some application of Cf-FAB is still reported, especially frit-FAB. 

Mass spectrometry is a valuble tool with which an abundancy of structural information may be obtained from a minute amount of material. Capillary electrophoresis may be interfaced with mass spectrometry by electrospray ionization [124-126] or continuous-flow, fast-atom bombardment methods [127,128]. Several reviews discuss applications of the interfacing techniques, and address the attributes and disadvantages associated with these methods [129,130]. Critical parameters involved in the optimization of CE-electrospray ionization mass spectrometry analysis have been reviewed as well [131],... 

Electrospray mass spectrometry utilizes a soft ionization technique at nearly atmospheric pressure. As a result, intact molecular ions are formed in high yield. The instrument can be interfaced readily to HPLC or capillary electrophoresis columns and sub-femtomole amounts of proteins can be detected. A disadvantage is that salt concentrations must be kept low (< mM) and that the protein tends to bind Na, K+, and anions that may confuse interpretation of spectra. 

Field desorption (FD) and fast atom bombardment (FAB) mass spectrometry provides mass spectral information about compotmds that are not very volatile but these two techniques are not used often in polymer science since they have several disadvantages. Electrospray ionization (ESI) mass spectrometry can also be used to obtain the above information about polymers, but ESI spectra are generally complicated due to differences in charge state distributions. Static secondary ion mass spectrometry (static SIMS) is a surface-sensitive MS technique, which is suitable for studying the interfaces of polymers with respect to chemical structure and molecular weight as well as end groups and surface contaminants. Laser desorption... 

The introduction of liquid samples into the mass spectrometer has proved especially difficult. However, the advent of electrospray ionisation (ESI) and atmospheric pressure chemical ionisation (APCI) have overcome this problem and revolutionized the interfacing of HPLC with mass spectrometry. This success has pointed the way toward a major change in the mass spectrometric analysis of vitamin D, its analogs, and their metabolites. A disadvantage at the present time is that ionization using ESI and APCI is less efficient than the EI(+) used in GC-MS, but the immediate advantage is that it obviates the need for derivatiza-tion. 

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