Patent FR-2827958-A1 (FR)
Title: Capillary tube device for analysis of laser-induced fluorescence of substances in solution, for detecting and dosing trace substances in chemistry and biochemistry
Inventor: COUDERC FRANCOIS
IPC: G01N30/74
Filed: 2001-07-25
Abstract: Capillary tube device for analysis of laser-induced fluorescence of substances in solution for detecting and dosing trace substances, has a tube wall comprised of a material with a refractive index below that of the water in a channel or above that of both the water in the channel and the air outside it.  The capillary tube device has a tube (2) with a channel (11) containing a solution with at least one substance which produces a laser-induced fluorescent reaction. The tube is made of material which is transparent to an exciting light, projected locally into part (16) of the channel at an angle greater than 60 deg  to the longitudinal axis (A) of the channel. An optical collector (7) collects the resulting fluorescent light from the channel and is coupled to an optical measuring device (8). The resulting signals are treated in (9) to produce an analysis of the solution. Near the second end of the tube is a conical, ellipsoidal or parabolic internal wall with one side turned towards the first end of the tube. The tube has a larger internal section than the outlet pipe and includes a fluorescence detection cell adjacent to the junction (4) connecting the separation unit outlet to the second end of the tube so the detection cell contains the excitation zone for the substance(s). The second end of the tube has an internal shoulder for the outlet pipe to butt against, of the same internal diameter as the outlet pipe. A hollow T connector (5) is placed so the top of the T connects the wave guide of the collector and the end of the tube. The foot of the T forms a side branch (30) for circulation of the solution and/or transport of the substance(s) in and out of the tube. This side branch connects the first end of the tube to a reservoir which has electrodes placed across the wall. The solution conducts electricity and the electrodes are connected so there is a difference in potential between the ends of the tube to migrate the substance(s) through the tube by electrophoresis. A second hollow T connector at the other end of the tube can connect straight through to a second collector and provides a side branch. The tube then contains a second conical, ellipsoidal or parabolic internal wall near the first end, with one side turned towards the second end of the tube. The internal walls are coated with a reflective material which is resistant to oxidation. The tube has an internal diameter of up to 200 micro m for using capillary electrophoresis and up to 1000 micro m for using HPLC. The exciting light is projected by a light source (12) at the side of the tube and optical means (14) between the light source and the channel to match the cross section of the light beam to the internal diameter of the channel. The external wall of the tube is coated with a reflective material except near the excitation zone of the detection cell which must be transparent to the beam (F). The excitation beam is elliptical, with the major axis perpendicular to the longitudinal axis of the capillary tube and the minor axis parallel to the longitudinal axis of the tube.  An Independent claim is also included for a device for separation by chromatography including an analysis device as described above.