Abstract: An apparatus for detecting a presence of at least one analyte in a gas sample. The apparatus comprises a pump for drawing a gas sample from an ambient air, a passage having first and second ends, a chamber connected to the first end and containing a concentrating element for collecting at least one analyte from the gas sample, a chromatographic separator connected to a second end of the passage, and a gas source for streaming a carrier gas via the chamber to transfer the at least one analyte toward at least one chemical detector, via the chromatographic separator, in a first direction. The pump draws the gas sample via the chamber in a second direction and the first and second directions are substantially opposing to one another.

Abstract: An apparatus for detecting a presence of at least one analyte in a gas sample. The apparatus comprises a pump for drawing a gas sample from an ambient air, a passage having first and second ends, a chamber connected to the first end and containing a concentrating element for collecting at least one analyte from the gas sample, a chromatographic separator connected to a second end of the passage, and a gas source for streaming a carrier gas via the chamber to transfer the at least one analyte toward at least one chemical detector, via the chromatographic separator, in a first direction. The pump draws the gas sample via the chamber in a second direction and the first and second directions are substantially opposing to one another.

Abstract: An apparatus for detecting a presence of at least one analyte in a gas sample. The apparatus comprises a pump for drawing a gas sample from an ambient air, a passage having first and second ends, a chamber connected to the first end and containing a concentrating element for collecting at least one analyte from the gas sample, a chromatographic separator connected to a second end of the passage, and a gas source for streaming a carrier gas via the chamber to transfer the at least one analyte toward at least one chemical detector, via the chromatographic separator, in a first direction. The pump draws the gas sample via the chamber in a second direction and the first and second directions are substantially opposing to one another.

Abstract: An apparatus for detecting a presence of at least one analyte in a gas sample. The apparatus comprises a pump for drawing a gas sample from an ambient air, a passage having first and second ends, a chamber connected to the first end and containing a concentrating element for collecting at least one analyte from the gas sample, a chromatographic separator connected to a second end of the passage, and a gas source for streaming a carrier gas via the chamber to transfer the at least one analyte toward at least one chemical detector, via the chromatographic separator, in a first direction. The pump draws the gas sample via the chamber in a second direction and the first and second directions are substantially opposing to one another.

Abstract: An apparatus for detecting a presence of at least one analyte in a gas sample. The apparatus comprises a pump for drawing a gas sample from an ambient air, a passage having first and second ends, a chamber connected to the first end and containing a concentrating element for collecting at least one analyte from the gas sample, a chromatographic separator connected to a second end of the passage, and a gas source for streaming a carrier gas via the chamber to transfer the at least one analyte toward at least one chemical detector, via the chromatographic separator, in a first direction. The pump draws the gas sample via the chamber in a second direction and the first and second directions are substantially opposing to one another.

Abstract: An apparatus for detecting a presence of at least one analyte in a gas sample. The apparatus comprises a pump for drawing a gas sample from an ambient air, a passage having first and second ends, a chamber connected to the first end and containing a concentrating element for collecting at least one analyte from the gas sample, a chromatographic separator connected to a second end of the passage, and a gas source for streaming a carrier gas via the chamber to transfer the at least one analyte toward at least one chemical detector, via the chromatographic separator, in a first direction. The pump draws the gas sample via the chamber in a second direction and the first and second directions are substantially opposing to one another.

Abstract: A concentration valve for a gas detecting apparatus including a cylinder having diametrally opposed inlet and outlet ports for a sample gas and having diametrally opposed inlet and outlet ports for a carrier gas longitudinally spaced from and in the same longitudinal plane as the sample-gas inlet and outlet ports, a cylindrical plug having a diametral passage therethrough and movable longitudinally of the cylinder between a sampling position wherein the diametral passage communicates with the sample-gas inlet and outlet ports and an analyzing position wherein the diametral passage communicates with the carrier-gas inlet and outlet ports, a pneumatic actuator for longitudinally moving the cylindrical plug between the sampling and analyzing positions, gas adsorbing means in the diametral passage for adsorbing a gaseous material or materials from the sample gas, and means for heating the gas adsorbing means in the analyzing position of the cylindrical plug to desorb the previously adsorbed gaseous material or ma