A system is described for determining the concentration of an analyte in a liquid by absorption measurement comprising a test element with a detection area which contains at least one reaction area with reagents for detecting the analyte which cause a change in the absorption behavior upon reaction with the analyte. The detection area contains at least one reference area in which the absorption behavior is substantially not changed when wetted by a sample having the analyte. Furthermore, the system contains a detection unit for the spatially resolved detection of light intensities which are received from the detection area and an evaluation unit for evaluating signals from the detection unit. Further embodiments of the system comprise reaction areas and reference areas arranged alternately in two dimensions.