a rigid reuseable metallic tube is provided with sealing screws at either end , operable to deform malleable lead washers against a labyrinth pattern at the extreme tube ends . in one embodiment , a wire form is disposed within the tube with an annular portion conforming to the tube interior , and an elongated wire depending therefrom , for holding the charcoal in place . in another embodiment , wire screen discs hold the charcoal in place , and utilize elongated pegs to remove the screen and withdraw the charcoal . plugs of glass wool may also be used to enclose the activated charcoal against the annulus and / or the screens . an orifice in the tube may be provided to restrict air flow through the charcoal . alternatively , a needle valve and flow meter may be used to regulate flow . an alternative embodiment is reuseable , and utilizes sintered metallic plugs press fit into and against the metallic tube , thereby giving rise to advantageous methods for removal of the sampled gases .