Interfaces for Coupling Liquid Chromatography with Mass Spectrometry

Another attempt to perform high-speed separation is to use ultrahigh or turbulent flows (over 30 mL/min) [13]. At turbulent flow rates, the solvent front profile is plug-like rather than the usual parabolic. Therefore, a considerable improvement in column efficiency is achieved. These prohibitive ultrahigh flow rates are, however, possible when columns are packed with particles over 50 p,m. 

INTERFACES FOR COUPLING LIOUID CHROMATOGRAPHY WITH MASS SPECTROMETRY 

The coupling of LC with mass spectrometry is not as straightforward as a similar combination of GC with MS. There are several fundamental differences in the operating environment of HPLC and mass spectrometry. The first mismatch is the solvent flow rate. The separation in conventional wide-bore analytical columns is accomplished at liqnid flow rates of 0.5 to 1.5 mL/min. Unlike GC/MS, this liqnid produces a gas flow too large for safe operation of the mass spectrometry vacnnm system (10 to 10 torr). For example, 1.0 mL of water will pro-dnce about 1.0 x 10 m of gas load when introduced in a mass spectrometer at 10 torr pressure (see Example 5.3). Liquid flow rates below 10 xL/min can be accepted safely by a mass spectrometry system. Another problem is the 

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INTERFACES FOR COUPLING LIQUID CHROMATOGRAPHY WITH MASS SPECTROMETRY... 

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