POROUS STAINLESS STEEL AS A CARRIER GAS SEPARATOR INTERFACE MATERIAL FOR GAS CHROMATOGRAPHY-MASS SPECTROMETRY

Silanized porous stainless steel of 0.1 micron mean pore size has been used as the interface material in an effusion-type carrier gas separator for gas chromatography-mass spectrometry. Two interface systems have been constructed, providing effluent introduction to the mass spectrometer either through a conventional direct inlet vacuum lock using a separator-probe assembly, or through a compact, permanently mounted unit. Efficiencies of 40-48% were measured for cholestane (MW 372) with column flow rates of 7 (entire column under vacuum) and 35 ml/min and ion source pressures of 2-4 — 10-5 mm Hg. Minimal tailing was observed for fatty acid esters, steroids and nucleoside derivatives. The M-18 peak of cholesterol was 34% of M for a sample introduced through the combination system (separator 250 °C) compared to 28% for conventional probe introduction at the same ion source temperature. © 1969, American Chemical Society. All rights reserved.