A method for inspecting a gas sample, comprising: a) providing an apparatus comprising: a T-shaped tubular element comprising a passage having first and second ends, and a first inlet/outlet; a chamber connected to said first end and containing a concentrating element for collecting at least one analyte from a gas sample; a pump for drawing said gas sample from ambient air via said first inlet/ outlet and said chamber in a first direction (path B); a chromatographic separator connected to the second end of said passage; at least one chemical detector connected to said chromatographic separator and having a second outlet; and a gas source for sequentially streaming a carrier gas along a first path (path D) and a second path (path A), said first path (path D) passing via said chamber to the first outlet without passing via the chromatographic separator and the at least one chemical detector, and the second path (path A) passing via said chamber to the second outlet in a second direction; wherein said first (path B) and second (path A) directions are substantially opposing to one another; wherein there are no valves along the passage between the chemical detector and the concentration element; b) using the pump to draw a gas sample from ambient air via said first inlet/ outlet and said chamber in a first direction (path B) so as to allow at least one analyte from said gas sample to be bonded to the concentration element; c) extracting impurities from said chamber by using the gas source to stream a carrier gas along the first path (path D) to the first outlet; d) heating said concentration element to release said at least one bonded analyte; e) streaming said carrier gas via said chamber and along the second path (path A) so as to carry said at least one released analyte to the second outlet, via the chromatographic separator and the detector; and f) reading an output of said detector for detecting at least one of the presence, the absence and the concentration of said at least one analyte. a) providing an apparatus comprising: a T-shaped tubular element comprising a passage having first and second ends, and a first inlet/outlet; a chamber connected to said first end and containing a concentrating element for collecting at least one analyte from a gas sample; a pump for drawing said gas sample from ambient air via said first inlet/ outlet and said chamber in a first direction (path B); a chromatographic separator connected to the second end of said passage; at least one chemical detector connected to said chromatographic separator and having a second outlet; and a gas source for sequentially streaming a carrier gas along a first path (path D) and a second path (path A), said first path (path D) passing via said chamber to the first outlet without passing via the chromatographic separator and the at least one chemical detector, and the second path (path A) passing via said chamber to the second outlet in a second direction; wherein said first (path B) and second (path A) directions are substantially opposing to one another; wherein there are no valves along the passage between the chemical detector and the concentration element; a T-shaped tubular element comprising a passage having first and second ends, and a first inlet/outlet; a chamber connected to said first end and containing a concentrating element for collecting at least one analyte from a gas sample; a pump for drawing said gas sample from ambient air via said first inlet/ outlet and said chamber in a first direction (path B); a chromatographic separator connected to the second end of said passage; at least one chemical detector connected to said chromatographic separator and having a second outlet; and a gas source for sequentially streaming a carrier gas along a first path (path D) and a second path (path A), said first path (path D) passing via said chamber to the first outlet without passing via the chromatographic separator and the at least one chemical detector, and the second path (path A) passing via said chamber to the second outlet in a second direction; wherein said first (path B) and second (path A) directions are substantially opposing to one another; wherein there are no valves along the passage between the chemical detector and the concentration element; b) using the pump to draw a gas sample from ambient air via said first inlet/ outlet and said chamber in a first direction (path B) so as to allow at least one analyte from said gas sample to be bonded to the concentration element; c) extracting impurities from said chamber by using the gas source to stream a carrier gas along the first path (path D) to the first outlet; d) heating said concentration element to release said at least one bonded analyte; e) streaming said carrier gas via said chamber and along the second path (path A) so as to carry said at least one released analyte to the second outlet, via the chromatographic separator and the detector; and f) reading an output of said detector for detecting at least one of the presence, the absence and the concentration of said at least one analyte.