| 摘要 |
The invention pertains to a sample injector for liquid chromatography, particularly for high performance liquid chromatography, with a controllable injection valve (3) that features at least one waste port (12) for discharging fluid under low pressure, two sample loop ports (13, 16) and two high-pressure ports (14, 15) for supplying and discharging fluid under high pressure, wherein one high-pressure port (15) can be connected to a pump (40) and the other high-pressure port (14) can be connected to a chromatography column (41), with a sample loop (44, 51, 52) that comprises a first sample loop section (51) that is connected to one of the sample loop ports (16) on one end and to a pump volume (V) of a sample conveying device (5) on the other end, as well as a second sample loop section (44, 52) that is connected to the other sample loop port (13) on one end and to the pump volume (V) of the sample conveying device (5) on the other end. The second sample loop section (44, 52) is realized such that it can be separated into an intake segment (44) and a feed segment (52). A sample fluid can be taken in with the free end of the intake segment (44) that is connected to the pump volume (V) in the separated state and supplied to the respective sample loop port (13) via the feed segment (52) in the connected state. The sample injector furthermore features a control unit (60) for controlling the injection valve (3) and the sample conveying device (5). The injection valve (3) is realized in such a way that, in a LOAD position, the two high-pressure ports (14, 15) are connected to one another and the sample loop port (13) connected to the second sample loop section (44, 52) is connected to the waste port (12), and that, in an INJECT position, the high-pressure port (15) connected to the pump (40) is connected to the sample loop port (16) connected to the first sample loop section (51) and the high-pressure port (14) that can be connected to the chromatography column (41) is connected to the sample loop port (13) connected to the second sample loop section (51) [sic; (52)]. According to the invention, the injection valve has a PRESSURE COMPENSATION position, in which the sample loop ports of the closed sample loop (44, 52, 51) in the injection valve (39 [sic; (3)] are tightly closed. The control unit (60) controls the injection valve and the sample conveying device in such a way that the injection valve (3) is changed over into the PRESSURE COMPENSATION position after taking in the sample fluid in the LOAD position and the pressure in the sample loop (44, 52, 51) is increased to essentially the operating pressure of the pump (40) by means of the sample conveying device (5) before changing over into the INJECT position, and/or in such a way that the injection valve (3) is changed over into the PRESSURE COMPENSATION position after injecting the sample fluid in the INJECT position and the pressure in the sample loop (44, 52, 51) is reduced to essentially the ambient pressure by means of the sample conveying device (5) before changing over into the LOAD position.
|
