Microliter-sized ionization device and method

A microliter-sized metastable ionization device for the detection of trace analytes mixed with a carrier gas, comprising:

• a center core, first and second gas inlets and a gas outlet;
• a first electrode having a hollow tubular end portion in fluid communication with both said first gas inlet and said center core for delivery of the analyte and carrier gas mixture into said center core;
• a second electrode having an annular gap forming means disposed around said hollow end portion of said first electrode, said gap forming means forming a substantially concentric and uniform annular gap between said first and second electrodes;
• said gap being in fluid communication with, on one side, said second gas inlet and, on the other side, said center core for delivery of a corona gas through said corona gap and into said center core;
• a means to generate a corona discharge across said corona gap for creating metastable forms of said corona gas as said corona gas passes through said gap;
• a collector having a hollow end portion in fluid communication with both said center core and a gas outlet for the outgassing of gases within said center core, said collector being aligned to receive gases expelled from said first electrode;
• and
• means to detect ions formed in said center core.

A method to detect trace analytes in a carrier gas comprising:

• (a) providing a microliter-sized ionization device with:
• (i) a center core, first and second gas inlets and a gas outlet;
• (ii) a first electrode having a hollow tubular end portion in fluid communication with both said first gas inlet and said center core;
• (iii) a second electrode having a gap forming means with an opening disposed around said hollow end portion of said first electrode, said opening having a diameter greater than an outside diameter of said hollow tubular end portion of said first electrode forming a substantially concentric and uniform annular corona gap therebetween;
• (iv) said corona gap being in fluid communication with both said second gas inlet and said center core;
• (v) a means to generate a corona discharge across said corona gap;
• (vi) a collector having a hollow end portion in fluid communication with both said center core and a gas outlet, said collector being aligned to receive gases expelled from said first electrode;
• and
• (vii) a means connected to said collector to detect ionized forms of the analyte;
• (b) introducing an analyte and carrier gas mixture into said center core through said first electrode;
• (c) introducing a corona gas through said annular gap into said center core;
• (d) generating a corona discharge across said corona gap thereby creating metastable forms of the corona gas which interact with and ionize the analytes;
• and
• (e) detecting ionized forms of the analyte in said collector with said detecting means.

A trace analyte detection system comprising:

• (a) a detector having a cavity, having first and second gas inlets and having a gas outlet;
• (b) a sample valve;
• (c) a source of a purified rare gas connected to both said second gas inlet and said sample valve;
• (d) a source of analytes connected to said sample valve;
• (e) a gas separator connected between said sample valve and said first gas inlet;
• and
• (f) wherein said detector further comprises:
• (i) an inner electrode having a hollow tubular end portion in said cavity in fluid communication with said first gas inlet;
• (ii) an outer electrode in fluid communication with said second gas inlet, said outer electrode having a gap forming means with an opening aligned concentrically with said end portion of said inner electrode forming a substantially uniform corona gap in fluid communication with both said second gas inlet and said cavity;
• and
• (iii) a collector having an opening in said cavity in fluid communication with said gas outlet.