32:Why is direct electron ionization in Figure 22-14 permissible for gas chromatography, but only for capillary columns in liquidchromatography in Figure 22-29?

A direct electron ionization liquid chromatography–mass spectrometry interface (Direct-EI LC-MS interface ) based on the direct introduction of the liquid effluent into an electron ionization (EI) source.

A direct electron ionization liquid chromatography–mass spectrometry interface (Direct-EI LC-MS interface ) is a technique for coupling liquid chromatography and mass spectrometry (LC-MS) based on the direct introduction of the liquid effluent into an electron ionization (EI) source.

Library searchable mass spectra are generated. Gas-phase EI has many applications for the detection of HPLC amenable compounds showing minimal adverse matrix effects. The direct-EI LC-MS interface provides access to well-characterized electron ionization data for a variety of LC applications and readily interpretable spectra from electronic libraries for environmental, food safety, pharmaceutical, biomedical, and other applications.