OPTIMIZATION OF THE INSTRUMENTAL PARAMETERS OF A COMBINED LIQUID CHROMATOGRAPH MASS-SPECTROMETER, COUPLED BY AN INTERFACE FOR DIRECT LIQUID INTRODUCTION .1. PERFORMANCE OF THE VACUUM EQUIPMENT

The direct introduction of liquid solutions into the vacuum space of a mass spectrometer for liquid chromatography-mass spectrometry (LC-MS) purposes requires that the vacuum pumping equipment for the apparatus evacuates very high throughputs of gas resulting from the vaporization of the solvent. Updating and testing of the vacuum equipment are then the first operations to be carried out before adapting a direct liquid introduction (DLI) interface to a chemical ionization mass spectrometer. The requirements of a sucessful DLI/LC-MS experiment are examined. The need for a cryopump with a large active surface area chilled at 80°K is emphasized. © 1979.