Method and apparatus for introduction of liquid effluent into mass

Abstract

Methods and apparatus for liquid sample introduction into chemical detectors that require the sample to be transformed from a flowing stream into either gaseous or particulate states. The effluent from either a process stream or a liquid chromatograph is nebulized by combined thermal and penumatic processes within an inner fused silicon capillary tube heated by conduction through a relatively conductive sheathing gas such as helium or hydrogen from a surrounding electrical resistance heated outer capillary tube composed of a pure metal having a comparatively high linear relationship between temperature and electrical resistance to provide a uniform conduction of heat energy to the inner tube to form a well-collimated, partially or completely desolvated aerosol, with the less volatile solute components of the sample stream remaining in the particulate state. An expansion chamber at atmospheric pressure or less pressure slows the sheathing gas which surrounds the solvent vapor and solute particles sufficiently to form a stream which carries the solute particles in a manner that they avoid impacting the walls of the expansion chamber. The gaseous components of the aerosol are then separated from the solvent-depleted solute particles using either cryotrapping or momentum separation. The enriched solute particles are vaporized, ionized, and/or detected by suitable gas-phase or particle detectors. The device is primarily an interface between the liquid chromatograph or process streams and the mass spectrometer.