Richard H Kolloff

US Patent:

44649258, Aug 14, 1984

Filed:

May 17, 1982

Appl. No.:

6/378662

Inventors:

Richard H. Kolloff - West Chester PA

Assignee:

Hewlett-Packard Company - Palo Alto CA

International Classification:

G01N 3108

US Classification:

73 231

Abstract:

A thermal conductivity detector is described in which the temperature of the filament and wall are such as to cause the output signal to be on one side of zero for all mixtures of hydrogen or deuterium in a carrier gas such as helium.

US Patent:

47350822, Apr 5, 1988

Filed:

Jul 14, 1986

Appl. No.:

6/885120

Inventors:

Richard H. Kolloff - West Chester PA

Assignee:

Hewlett-Packard Company - Palo Alto CA

International Classification:

G01N 2518

US Classification:

73 27R

Abstract:

A thermal conductivity detector comprised of a Wheatstone bridge having a filament in one arm thereof that is contained within a cavity through which the elutant from a column is passed and means for deriving an output signal from one diagonal of the bridge when the voltage applied across the other diagonal is changed from a small value to a large value. In one embodiment, the voltage applied across the one diagonal of the bridge is changed from a fixed low value to a fixed high value and the output signal is the change in the voltage appearing across the other diagonal. In another embodiment, the voltage applied across the one diagonal of the bridge varies from a low value to a value required to keep the bridge in balance, and the difference between these voltages is the output signal.