TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The material is ability to react with (B) to form at least one involatile compound. The material comprises a metal to react with (B) to form a metal halide. The metal comprises group (I-IV) elements (preferably titanium or zirconium). The material is heated at above 200 (preferably 250-650)degreesC. The residence time of the stream within the material is greater than 0.1 (preferably greater than 1) second. The material defines a tortuous path for the passage of the stream there through. The material comprises a plurality of voids defining the tortuous path or a foam or sponge through which the stream is conveyed. The stream is brought into contact with a second material that reacts with hydrogen to form water. The second material comprises a metal oxide or metal oxide rich reagent e.g. copper oxide or iron oxide at 250-650degreesC. The stream is conveyed firstly into a first reactor containing the first-mentioned material and subsequently into a second reactor containing the second material. The gas is conveyed into a single reactor sub-divided into two zones by the first material and the second material. The stream is subsequently dried to remove any water. The noble gas comprises xenon, krypton and/or argon. The halogen-containing component of the stream comprises a fluorine-containing component. The fluorine-containing component of the stream comprises fluorine, a perfluoro compound or hydrofluorocarbon compound. The component comprises fluorine gas (F2), tetrafluoro methane (CF4), hexafluoro ethane (C2F6), octafluoro propane (C3F8), octafluoro butane (C4F8), trifluoro methane (CHF3), pentafluoro ethane (C2HF5), difluoro methane (CH2F2), trifluoro amine (NF3) or thio hexafluoride (SF6). (B) is removed from the stream at a sub atmospheric pressure. The noble gas is pressurized prior to its return to the process tool. The recovered noble gas is used as a purge gas for a vacuum pump used to draw the effluent stream from the process tool.