| 摘要 |
A thermal conductivity detector (5) for a gas chromatograph comprises a heatable resistive detector element (8, R2) configured to be physically arranged in a flow of analytes eluting from a chromatography column (4) and electrically arranged together with resistors (R1, R3, R4) in separate arms of a measuring bridge. The detector (5) further comprises an amplifier (U1) configured to detect a differential voltage between two opposite nodes of the measuring bridge and to apply an output voltage (10) to the other opposite nodes of the measuring bridge in order to maintain the detector element (8, R2) at a constant operating temperature. In order to compensate for uncertainties in the operating temperature due to manufacturing variations of the resistors (R1, R3, R4) and/or to allow for processing both small and large peaks of a chromatogram with highest resolution available, an additional resistor (R5) with a controllable switch (Q1) in parallel is connected in series with the detector element (8, R2) or resistor (R1, R3, R4) arranged in one arm of the measuring bridge. The switch (Q1) is periodically turned on and off with a predetermined duty cycle and/or controlled by information (12) on characteristic times-of-arrival of the analytes at the detector. |
