Abstract: In accordance with the present invention, a compliant pressure differential is applied across a separation column while its inlet is in a sample solution so that sample solution is introduced into the column. The profile of pressure differential over time is selected so that a desired volume of sample solution is introduced. Pressure and time are controlled with sufficient precision to yield repeatability of 5%, and preferably within 1%, by volume. The pressure differential is sufficiently low and the time sufficiently long that an acceptable velocity profile can be achieved.

Abstract: In accordance with the present invention, a compliant pressure differential is applied across a separation column while its inlet is in a sample solution so that sample solution is introduced into the column. The profile of pressure differential over time is selected so that a desired volume of sample solution is introduced. Pressure and time are controlled with sufficient precision to yield repeatability of within 5%, and preferably within 1%, by volume. The pressure differential is sufficiently low and the time sufficiently long that an acceptable velocity profile can be achieved.

Abstract: A method and apparatus for the injection of a quantitatively defined volume of at least one fluid into a tube or capillary, in particular suitable for capillary electrophoresis systems by immersing at least one end of the tube or capillary in the fluid to be injected in the tube or capillary and generating an overpressure in a space above the surface of the fluid to be injected, wherein said overpressure is generated by means of a syringe device comprising a cylinder and a piston movable in a controlled manner in the cylinder, said cylinder being filled with a suitable gas and being connected via a pressure line to said space above the surface of the fluid to be injected.