An apparatus comprising: a housing defining a slot; a reaction support unit; a friction bearing within the slot configured to couple to the reaction support unit, the reaction support unit comprising at least two light permeable channels configured to receive at least one reaction substance, the at least one reaction substance changing color in presence of at least one particular gaseous or vaporous component; a gas conveyance device configured to convey gas through at least one channel of the reaction support unit; an optoelectronic detection device configured to detect a color change of the at least one reaction substance on the reaction support unit during and/or after the conveyance of the gas mixture, the color change being detected in the direction of flow of the gas mixture through the at least two channels in at least two separate positions, the optoelectronic detecting device comprising a digital camera, the digital camera having an image converter or image sensor, and an imaging optics system; an evaluating device configured to evaluate the data detected by the optoelectronic detection device; a sensory feedback device configured to provide sensory feedback characterizing the data evaluated by the evaluating device; and a gas connector configured to be moved between two positions, and which is fluidically connected to the gas conveyance device, so that, in a first position of the gas connector, no fluidic connection between the gas connector and one of the channels exists, and in a second position of the gas connector, a fluidic connection between the gas connector and one of the channels exists, and wherein the reaction support unit comprises at least two indicator pins, wherein each indicator pin is associated with one of the channels and is configured to be moved between two positions, wherein by bringing the gas connector in contact with the indicator pin during a movement of the gas connector from the first position of the gas connector to the second position of the gas connector the indicator pin is moved from a first position of the indicator pin to a second position of the indicator pin. a housing defining a slot; a reaction support unit; a friction bearing within the slot configured to couple to the reaction support unit, the reaction support unit comprising at least two light permeable channels configured to receive at least one reaction substance, the at least one reaction substance changing color in presence of at least one particular gaseous or vaporous component; a gas conveyance device configured to convey gas through at least one channel of the reaction support unit; an optoelectronic detection device configured to detect a color change of the at least one reaction substance on the reaction support unit during and/or after the conveyance of the gas mixture, the color change being detected in the direction of flow of the gas mixture through the at least two channels in at least two separate positions, the optoelectronic detecting device comprising a digital camera, the digital camera having an image converter or image sensor, and an imaging optics system; an evaluating device configured to evaluate the data detected by the optoelectronic detection device; a sensory feedback device configured to provide sensory feedback characterizing the data evaluated by the evaluating device; and a gas connector configured to be moved between two positions, and which is fluidically connected to the gas conveyance device, so that, in a first position of the gas connector, no fluidic connection between the gas connector and one of the channels exists, and in a second position of the gas connector, a fluidic connection between the gas connector and one of the channels exists, and wherein the reaction support unit comprises at least two indicator pins, wherein each indicator pin is associated with one of the channels and is configured to be moved between two positions, wherein by bringing the gas connector in contact with the indicator pin during a movement of the gas connector from the first position of the gas connector to the second position of the gas connector the indicator pin is moved from a first position of the indicator pin to a second position of the indicator pin.