Patent ID: 8071957

Claim:
An ionization source assembly comprising: a tube having a first end and a second end, wherein the tube is configured to receive a gas including a sample flowing into the first end of the tube; an ionization source attached to the tube, the ionization source comprising: a center post extending therefrom; a plurality of needles extending from the ionization source, wherein the plurality of needles extend substantially parallel to the center post, wherein the center post is positioned substantially in the center of the plurality of needles, and wherein the plurality of needles are coupled to an electrical supply; and a counterelectrode ring extending around the ionization source, wherein the center post and the plurality of needles extend through the counterelectrode ring, and wherein the plurality of needles is configured to form a gas discharge upon application of a first voltage to the plurality of needles, and wherein the center post, the plurality of needles, and the counterelectrode ring are positioned inside of the tube and configured to be exposed to the gas including the sample entering the first end of the tube; wherein the tube is configured to permit (a) the interaction of the reactant ions in the gas discharge and the sample to produce sample ions and (b) the exit of the sample ions from the second end of the tube.