Atmospheric pressure ionization with optimized drying gas flow

An apparatus for use in atmospheric pressure ionization, comprising:

• a sample receiving chamber;
• a sample droplet source communicating with the sample receiving chamber;
• an outlet conduit defining a sampling orifice communicating with the sample receiving chamber;
• and
• means for directing a flow of drying gas into the chamber according to an elongated flow profile and in a non-coaxial, generally counterflow relation to a flow of droplets from the sample droplet source.

A method for evaporating droplets of sample material in an atmospheric pressure ionization apparatus, comprising:

• admitting sample material into a chamber as a sample droplet stream;
• directing the sample droplet stream toward an opening and a sampling orifice, wherein the chamber and sampling orifice are positioned at opposite sides of the opening and the sampling orifice leads away from the chamber;
• and
• while directing the sample droplet stream, admitting a flow of drying gas through the opening and into the chamber in a non-coaxial, generally counterflow relation to the sample droplet stream and according to an elongated flow profile, whereby the elongated flow profile presents an elongated area in which droplets of the sample droplet stream contact the drying gas for enhancing evaporation of the droplets prior to entry of sample material into the sampling orifice.