Direct-liquid-introduction interface disadvantages

Seven different LC-MS interfaces are described in Chapter 4, with particular emphasis being placed on their advantages and disadvantages and the ways in which the interface overcomes (or fails to overcome) the incompatibilities of the two techniques. The earlier interfaces are included for historical reasons only as, for example, the moving-belt and direct-liquid-introduction interfaces, are not currently in routine use. The final chapter (Chapter 5) is devoted to a number of illustrative examples of the way in which LC-MS has been used to solve various analytical problems. 

LC-MS inlet probes support all conventional HPLC column diameters from mobile phase must be eliminated, either before entering or from inside the mass spectrometer, so that the production of ions is not adversely affected. The problem of removing the solvent is usually overcome by direct-liquid-introduction (DLI), mechanical transport devices, or particle beam (PB) interfaces. The main disadvantages of transport devices are that column... 

Instrumentation for Capillary SFC-MS. The development of fused silica capillary colusms with stabilized stationary phases suitable for SFC presented the opportunity to eliminate the disadvantages of the molecular beam approach. The typical fluid flow rates for 50 ym i.d. columns are in the range of 1-2 1/min (as liquid) this range can be handled by conventional two stage mass spectrometers (as typically configured with chemical ionization capability) without the use of the liquid nitrogen cryo-pumps required for commercial direct liquid introduction LC-MS interfaces (35). 

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