Process for taking micro-samples of a fluid under pressure, particularly for chromatography, uses container connected to transfer circuit containing carrier fluid passing through orifice at end of capillary tube

摘要

The container (1) holding the fluid is connected to a transfer circuit (6) containing a carrier fluid passing through an orifice (4) at the end of a capillary tube (5). The orifice is opened and closed by a piston (7), which is driven by deforming an expandable sealed chamber (8) containing the piston, so the seal around the piston is ensured without recourse to a sliding sealed joint. The pressure in a chamber (10) containing the expandable chamber is balanced so it is at least 2 bars greater than that of the fluid contained in the expandable chamber, so the pressure difference between the two chambers helps to move the piston. The piston is moved by deforming the expandable chamber using a jack, in particular a pneumatic jack. The time between two consecutive displacements in opposite directions is controlled so it is possible to control the quantity of fluid taken. The duration of the piston displacement is controlled to control the quantity of fluid taken. An Independent claim is included the apparatus for the above process, comprising a container (1) with a capillary orifice (4) at the end of a capillary tube (5), a transfer circuit (6) and a movable piston (7) which can occupy two positions, closing or opening the orifice. The piston is contained in a deformable expandable chamber (8) and has a means of operation.