Method and apparatus for the introduction of a volume of at least one fluid in a tube, in particular suitable for capillary electrophoresis systems and method and apparatus for separating and/or analyzing a fluid material

Claim 1

A method for the injection of a quantitatively defined volume of at least one fluid sample into a tube or capillary (11) by means of gas pressure, in particular suitable for capillary electrophoresis systems, by immersing at least one end of the tube or capillary (11) in the fluid to be injected into the tube or capillary and generating an over pressure in a sealed space above the surface of the fluid to be injected, characterized by introducing said volume of the fluid into the tube or capillary by using a syringe device (1,2;20) comprising a cylinder (1;22) and a piston (2;21) and piston displacement control means for moving the piston in the cylinder in a controlled manner, said cylinder being filled with a suitable gas and being connected to the space above the surface of the fluid to be injected into the tube or capillary (11); compressing in a compression phase (C) said suitable gas by moving the piston in a controlled way in the cylinder; and decompressing in a decompression phase (D1) said gas by moving the piston in a controlled way in the cylinder such that the compression phase and the decompression phase are substantially mirror images of the pressure-time profile caused by the movement of the piston.

Claim 6

A method as claimed in any one of claims 1-5, characterized by closing the other end of the tube or capillary (11) prior to generating an overpressure in a space above the surface of the fluid to be injected by means of the syringe device (1,2;20); opening for a predetermined length of time the said other end of the tube or capillary (11) so that said at least one fluid flows into the tube or capillary (11) and closing the said other end again after said predetermined length of time, whereby a quantitatively defined volume of said at least one fluid is introduced in the tube or capillary (11).

Claim 7

A method as claimed in any one of the preceding claims, characterized in that after the injection of said at least one fluid, at least one second fluid is injected in similar manner.

Claim 9

A method as claimed in any one of claims 5-8, characterized in that the syringe device (1,2;20) is vented when the piston (2;21) moves from the first section to the second section.

Claim 10

A method for separating and/or analyzing a fluid material comprising a mixture or solution containing at least two components by chromatography, electrophoresis, or filtration, with or without applying a pH gradient, in a tube (11), wherein the fluid is introduced into the said tube (11) using the method of any one of claims 1-9.

Claim 11

An apparatus for injecting a quantitatively defined volume of at least one fluid sample into a tube or capillary (11) by means of gas pressure, in particular suitable for electrophoresis systems, said apparatus comprising pressure generating means and means (40) for receiving a fluid receptacle (9;54), characterized in that the pressure generating means comprises a syringe device (1,2;20) having a cylinder (1;22), a piston (2;21) movable in the cylinder and piston displacement control means including drive means for the piston, said cylinder being connected by a pressure line (7;24) to a pressure space above the fluid in the receptacle wherein the piston displacement control means is arranged to move the piston in a compression phase (C) and a decompression phase (D1) such that the compression phase and the decompression phase are substantially mirror images of the pressure-time profile caused by the movement of the piston.

Claim 16

An apparatus as claimed in any one of claims 11-15, characterized in that the piston (21) has a piston rod (27) extending through an end wall of the cylinder and being connected in driving relationship by a nut element and threaded rod device (31) to a stepping motor (32).

Claim 19

An apparatus as claimed in any one of claims 11-18, characterized in that the means (40) for receiving a fluid receptacle comprises a vial socket (48) having a cone shaped vial reception space (47) for receiving the mouth of a vial (9;54), said vial socket having at the top of the cone shaped space a bore (50) connecting the cone shaped space (47) with said pressure space.

Claim 22

An apparatus as claimed in any one of claims 19-21, characterized in that the means for receiving a fluid receptacle (9;54) comprise a first box-like element (42) connected by at least one arm (44,45) to a second box-like element (43) substantially parallel to said first box-like element (42), wherein said second box-like element (43) is arranged to move along the at least one arm (44,45) to and from the first box-like element (42) between a non-operative position (fig 3) and an operative position (fig 4), and wherein the first box-like element (42) is provided with means (52) for clamping the tube or capillary (11), wherein between the first and second box-like elements (42,43) a cross-piece (46) supporting an electrode (12a) is provided.

Claim 25

An apparatus as claimed in any one of claims 13-24, characterized in that the cylinder (1;22) has a first section for piston movement below the hole (26), and a second section beyond the hole (26), wherein the space above the piston is connected to the buffervessel (25) as long as the piston is in the first section, while the space above the piston is disconnected from the buffervessel (25) if the piston is in the second section.

Claim 26

An apparatus for separating and/or analyzing a fluid material comprising an apparatus for injecting a volume of fluid as claimed in any one of claims 11-25 and a tube or capillary (11) having an inlet end and an outlet end and detector means (16) placed adjacent the tube or capillary (11), characterized in that at least at the outlet end of the tube or capillary (11) a controllable closing means (14,15) is provided for closing or opening said end of the tube or capillary (11) at desired points of time.