Abstract: A measuring assembly comprises a supporting element transparent to excitation and measurement radiation, which is provided with a number of preferably different luminescence-optical sensor elements on a first boundary face. Via a second boundary face excitation radiation can be picked up, and a third boundary face is used to supply measurement radiation of the sensor elements to a detector of an evaluation unit. The direction of the excitation radiation is essentially normal to that of detection. The preferably different sensor elements are connected by a common sample channel, and optical and/or temporal separation of the measurement radiation of the individual sensor elements is provided.

Abstract: In a method of optically determining the total hemoglobin concentration (tHb) in non-hemolyzed whole blood, using at least two wavelengths for measuring, a first wavelength of .lambda.<805 nm and a second wavelength of .lambda.>805 nm is employed, such the following is valid for the absorption coefficients of hemoglobin derivatives O.sub.2 Hb and RHb at the two measurement wavelengths .lambda..sub.1 and .lambda..sub.2 : .sigma.O(.lambda..sub.1).about..sigma.R(.lambda..sub.2) and .sigma.R(.lambda..sub.1).about..sigma.O(.lambda..sub.2). The sum of absorption values A.sub.1 and A.sub.2 measured at wavelengths .lambda..sub.1 and .lambda..sub.2 will be a quantity which is proportional to the total hemoglobin concentration tHb and independent of the oxygen saturation O.sub.2sat.