| 摘要 |
<p>A dosing device has a flow divider (5) connected between a carrier gas source (1) and a gas chromatography separating column, in particular a capillary column. The flow divider has a conduit with an opening (8) and a chamber (7) surrounding said conduit with a delivery line (11) for the gas sample. The gas sample is taken from the sampling gas source (13) through a metering valve (12) with a metering loop (16) at low pressure and passed, together with the carrier gas at higher pressure, into the flow divider. A pressure drop can be reversed by means of a reversing valve (3) connected to the carrier gas source (1) so that in a first switching position the sample can enter the chamber (7) and in a second switching position a fraction of the sample corresponding to the dividing ratio in the flow divider can pass through the opening (8) in the conduit (6) into the separating column (26). The advantages of the metering device and its operating procedure are that it functions independently of the pressure of the sampling gas source and that, by suitable choice of the switching time-intervals of the metering and switching valves, sampling can be effected exactly as required.</p> |
