Abstract: A method and an arrangement detect harmful substances while eliminating or minimizing the drawbacks of an ion mobility spectrometer (IMS). The sample gas flow is mixed with a reference gas utilizing a pump (7). A reaction gas is supplied via a metering unit (10) to the ion-mobility spectrometer (2) when complex ion-mobility spectrometer spectra are present. The measurement signals obtained as to the gas-quantity ratio between the sample gas and the reference gas are adapted to the original concentration and are then compared to previously defined and stored measured values via a signal height comparison or a pattern recognition. The measuring system is rinsed following the measurement phase by feeding the reference gas and is cleaned by metering an additional cleansing gas when harmful substances are detected which could be rinsed away. Such methods and measuring systems are used for identifying harmful substances in ambient air.

Abstract: The aim of the invention is to improve the identification of individual gas compounds which co-exist with other compounds that have substantially higher concentrations. To achieve this, the adsorbent (2) is heated in a cyclic manner by a thermal shock treatment of the gas sensor (4) and the compounds that are released in cycles are diffused from the measured gas side through the membrane-type adsorbent (2) to the gas sensor (4) and are detected by the latter (4). The adsorbent (2) of the corresponding detector is configured as a flat or tubular membrane and is positioned directly adjacent to the gas sensor (4), without touching the latter. The adsorbent (2) separates the gas sensor (4) from the measured gas and is heated in a cyclic manner by the heater (6) of the gas sensor (4) in such a way that the desorbed gaseous compounds are identified using the active layer (5) of the gas sensor (4).

Abstract: The invention relates to a device for identifying gaseous compounds, comprising a sensor array (1) having, for instance, ten gas sensors (2) in the form of semiconductor gas sensors. Said sensor array (1) has a supply line (3) with an inlet (4) and an outlet (5). A switchable three-way valve (6) is located in the supply line (3), to which a selective collector unit (7) is attached. Said collector unit (7) comprises a special adsorber (8), a heater (9) and a separate feed pump (10) with a flow sensor (11). A secondary line (12), in which a dilution unit (13) is arranged, discharges into the feed line (3) between the three-way valve (6) and the sensor array (1). A feeding and control unit (16) also having a feed pump (17) with a flow sensor (18) is located in the area of the outlet (5) of the sensor array (1). An electrical line (19) leading to an evaluation computer (20) branches off from the sensor array (1).

Abstract: A method and apparatus for separating selected materials in a gas chromatograph. The gas mixture is introduced into a separation column of the gas chromatograph and the separation column is heated inside a chamber of the gas chromatograph to a preset temperature. The preset temperature is matched to the material to be separated and that heating is accomplished by using IR radiation.