Apparatus and method for detection of blood or a blood component or determining the concentration of blood or a blood constituent in a liquid

The invention relates to an apparatus and a method for detection of blood or a blood component or determining the concentration of blood or a blood constituent in a liquid, in particular for the detection of hemoglobin in a dialysis solution. The inventive device has a light transmitter 13 for transmitting light in a first wavelength range and to transmit light in a second wavelength range, wherein the wavelength of light are matched in the first and second wavelength range in such a way on the wavelength-dependent absorption characteristics of blood or blood component, that the light passing through the liquid light is absorbed in the first wavelength range more than the light passing through the liquid light in the second wavelength range. In addition, the apparatus comprises a light receiver 13 for receiving the passing through the liquid light and a computing and evaluation unit 15 which is formed such that the on the basis of the different absorption of the light with the wavelength in the first and second wavelength range presence of blood or a blood component is closed in the liquid. A particularly high measurement accuracy and safety evaluation in particular for the detection of hemoglobin in dialysis fluid is reached when the first wavelength range between 400nm and 450nm is.