The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 06, 1999
Filed:
Sep. 30, 1997
Mahmoud F Abdel-Rahman, West Grove, PA (US);
Hewlett-Packard Co., Palo Alto, CA (US);
Abstract
An ionization detector having an upper ionization chamber, a lower ionization chamber, and a radioactive source located in the upper ionization chamber but shielded from the lower ionization chamber by a barrier. A substantially constant fluid stream of detector gas is supplied to the upper ionization chamber so as to fill the upper ionization. The radioactive particle emitter is disposed on the periphery of the interior of the upper ionization chamber so as to generate a constant supply of alpha particles into the internal volume defined by the upper ionization chamber. The interaction of the alpha particles and the detector gas generates metastables and photons as the alpha particles traverse a portion of the volume in the upper ionization chamber. The lower ionization chamber is coupled to the upper ionization chamber so as to receive the detector gas flow and the metastables. A sample fluid is directed into the lower ionization chamber, preferably by way of a carrier gas flow supplied from an outlet end of a capillary separation column, and the metastables present in the lower ionization chamber then ionize the analyte molecules. An outlet is provided in the base of the lower ionization chamber so as to vent the combined flows of the carrier gas, sample fluid, and the detector gas. In the preferred embodiment, the carrier gas and the detector gas are helium. The barrier is interposed in the path between the radioactive source and the lower ionization chamber so as to prevent entry of the radioactive particles into the lower ionization chamber where there may ensue some interaction of the radioactive particles with analyte molecules in the lower ionization chamber. As a result, the primary mechanism for ionization of the analyte molecules is substantially restricted to an interaction of the metastables with the analyte molecules.