Abstract: A multicapillary electrophoresis system includes juxtaposed capillaries, at least one source configured for the emission of a light beam intended to excite molecules lying in its path and inside the capillaries and detects the fluorescence of the molecules excited by the light beam. Light that emerges at the exit of the capillaries and that propagates along the direction in that the capillaries extend is detected. The resolution for detection is high enough to distinguish light that emerges at the exit of each of the capillaries. A first liquid is located outside of the capillaries. A second liquid is located inside of the capillaries. The first liquid has a first refractive that is equal to or greater than the refractive index of the second liquid. A mirror is facing the source on the side of the capillaries which is opposed to the source.

Abstract: A method of injecting a sample into an electrophoresis capillary, in which method the capillary (1) is plunged into the sample and an electric field is applied between the ends of the capillary (1) to cause the sample to migrate into the capillary (1), the method being characterized in that the sample is previously introduced into a part (3) presenting a channel (4) of dimensions perpendicular to the direction in which said channel (4) extends that are smaller than about four times the outside diameter of the capillary (1), and in that in order to plunge the capillary (1) into the sample, said capillary (1) is introduced into said channel (4).