Abstract: The invention concerns a process for validation of devices for photometry of living tissue, which encompasses the following steps:

Abstract: The invention concerns a process for validation of devices for photometry of living tissue, which encompasses the following steps:in vitro adjusting of a particular concentration of a substance to be detected in a bodily fluid;transporting the bodily fluid which has been adjusted to a pre-determined concentration to at least one measuring cell;transillumination of the bodily fluid; andsensing of the light intensity of at least one spectral window for determination of at least one suitable parameter in the bodily fluid, which is contained in the measuring cell, by means of at least one emitter and at least one receiver;thereby characterized,that one actively and in a defined manner dynamically changes the effective absorption length through the bodily fluid, without using the bodily fluid for transmission of the forces, wherein the bodily fluid is found in the optical space between the emitter and the receiver; andestablishment of at least one relationship between the concentration on the one hand and the suit