| 摘要 |
In a gas chromatograph, components of a sample of a gas mixture (1) are separated by means of at least one separation column (4, 6). A sensing element (5', 7') of a thermal conductivity detector (5, 7) is arranged downstream from the separation column (4, 6) and operated at a first temperature to detect the separated components and to generate a detector signal (S5, S7) in response to each of the detected components. An evaluation unit (26) evaluates the detector signals (S5, S7) and determines the concentrations of the detected components. In order to detect gas components of widely different concentration ranges at high sensitivity, a further sensing element (11', 12') of a further thermal conductivity detector (11, 12) is arranged immediately downstream or upstream from the thermal conductivity detector (5, 7) and operated at a second temperature different from said first temperature. The thermal conductivity detector (5, 7) and the further thermal conductivity detector (11, 12) are calibrated for different concentration ranges. The evaluation unit (26) compares the detector signal (S5, S7) with the detector signal (S11, S12) of the further thermal conductivity detector (11, 12) to output a concentration value determined from the signal of the thermal conductivity detector that is calibrated for the concentration of the component measured. |
