Optical detection arrangement for small volume chemical analysis of fluid samples

An optical detection arrangement for small volume chemical analysis of fluid samples, comprising a light source, a capillary tube and a photoelectric detector, which is connected with an evaluation electronics, wherein the arrangement of the light source relative to the capillary tube is such, that probing light emitted from the light source strikes a sample to be analyzed, which is flowing through the capillary tube, whereas the photoelectric detector is arranged relative to the capillary tube such, that it is capable of detecting sample light coming from the capillary tube, wherein probing light is guided between said light source and said capillary tube essentially in a probing light guiding means, which is made of a material having a coefficient of thermal expansion comparable to the coefficient of thermal expansion of the capillary tube and a refractive index gradient about perpendicular to a direction of propagation of said probing light, and which is connected to said capillary tube in a mechanically stable manner by means of a light transparent adhesive having a refractive index which matches that of the wall material of said capillary tube within about 20%, the light guiding means being connected to the capillary tube such that said probing light exiting the guiding means travels through the transparent adhesive and strikes an inner wall of said capillary tube.