A device for extracting a vaporizable analyte from a sample gas containing the analyte and unwanted aerosol particles comprises; a vapour extraction chamber 2, first 3 and second 4 inlets, and first 5 and second 6 outlets; the chamber being provided with a heat source for heating the chamber to facilitate vaporization of analyte in the sample gas; the first inlet allowing a gas sample to be introduced into the chamber 2; the second inlet 4 being connected to a clean gas supply; in use laminar sample gas flow 7 is established through the chamber between inlet 3 and outlet 5, and laminar clean gas flow 8 is established through the chamber between inlet 4 and outlet 6; whereby analyte in vapour form in the sample gas flow 7 diffuses into the clean gas flow 8 reaching the second outlet and is substantially free of said unwanted aerosol particles; the first outlet 5 being a waste outlet for the sample gas flow, and the second outlet 6 being connected to an instrument for analysing analyte diffused into the clean gas flow.
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