Abstract: In a method for calibrating a biosensor for the amperometric determination of creatinine in biological liquids, consisting of one electrode system each for measuring the concentrations of creatinine and creatine, with at least two calibration solutions being used, the electrode system for measuring the creatinine concentration is calibrated with a creatinine solution which, prior to the calibration measurement, was mixed in the form of an acidic solution with an alkaline buffer solution, and the electrode system for measuring the creatine concentration is calibrated with a solution in which creatinine and creatine are at a thermodynamic equilibrium.

Abstract: In a method for calibrating a biosensor for the amperometric determination of creatinine in biological liquids, consisting of one electrode system each for measuring the concentrations of creatinine and creatine, with at least two calibration solutions being used, the electrode system for measuring the creatinine concentration is calibrated with a creatinine solution which, prior to the calibration measurement, was mixed in the form of an acidic solution with an alkaline buffer solution, and the electrode system for measuring the creatine concentration is calibrated with a solution in which creatinine and creatine are at a thermodynamic equilibrium.

Abstract: In a method for calibrating a biosensor for the amperometric determination of creatinine in biological liquids, consisting of one electrode system each for measuring the concentrations of creatinine and creatine, with at least two calibration solutions being used, the electrode system for measuring the creatinine concentration is calibrated with a creatinine solution which, prior to the calibration measurement, was mixed in the form of an acidic solution with an alkaline buffer solution, and the electrode system for measuring the creatine concentration is calibrated with a solution in which creatinine and creatine are at a thermodynamic equilibrium.

Abstract: In a method for calibrating a biosensor for the amperometric determination of creatinine in biological liquids, consisting of one electrode system each for measuring the concentrations of creatinine and creatine, with at least two calibration solutions being used, the electrode system for measuring the creatinine concentration is calibrated with a creatinine solution which, prior to the calibration measurement, was mixed in the form of an acidic solution with an alkaline buffer solution, and the electrode system for measuring the creatine concentration is calibrated with a solution in which creatinine and creatine are at a thermodynamic equilibrium.

Abstract: A control or calibration standard for use with instruments for the optical measurement of the hemoglobin content in blood samples, features scattering particles or beads dispersed in aqueous electrolyte solution. To prevent sedimentation of the beads during storage, they have a mean diameter of <0.6 &mgr;m, preferably about 0.3 &mgr;m, and a volume concentration of <1%, preferably <0.3%. To prevent long term agglomeration, a non-ionic surfactant with an added antioxidant can be included in the formulation.

Abstract: In a process for mixing two initial solutions to produce a working solution with an accurately defined mixing ratio, the two initial solutions are coarsely mixed in a first step, having a mixing ratio lying within a given range, and the value of an internal parameter of the working solution is determined in a second step. The values of this internal parameter are known and differ significantly for the two initial solutions. Then the accurate mixing ratio of the working solution is determined from the measured value of the internal parameter in a third step.

Abstract: In order to calibrate a measurement apparatus used for determining at least the pH and pCO.sub.2 values in aqueous media, two aqueous base solutions A and B with good storage stability are mixed at a defined ratio immediately prior to calibration, the desired pH and pCO.sub.2 values being provided for calibration of the measuring electrodes of the measurement apparatus only after chemical reaction of the base solutions A and B has taken place.

Abstract: Due to the size of the devices used for the excitation and measuring of light, conventional sensor elements for optically determining the concentrations of substances contained in gaseous and liquid samples, featuring an indicator layer with one or more indicator substances, are not well suited for use with microanalysis equipment, nor are they easy to mass-produce. These disadvantages are eliminated by integrating on the carrier layer (1) at least one photosensitive element (3) and its electric contact leads in planar arrangement, and by establishing optical contact between the indicator substance (7, 7') of the indicator layer (6) stimulated by the excitation radiation (11), and the photosensitive elements (3).

Abstract: Due to the size of the devices used for the excitation and measuring of light, conventional sensor elements for optically determining the concentrations of substances contained in gaseous and liquid samples, featuring an indicator layer with one or more indicator substances, are not well suited for use with microanalysis equipment, nor are they easy to mass-produce. These disadvantages are eliminated by using a unitary sensor element having a carrier layer, at least one photosensitive element with electric contact leads in contact with the carrier layer, and an indicator layer containing an indicator substance.

Abstract: A sensor element useful in making fluorescence-optical measurements includes a substrate having a carrier surface, particles having a large specific surface are which are glued, melted or sintered onto the carrier surface so as to provide small elevations of a regular distribution on the carrier surface, and an indicator substance immobilized on the particles. Additional substances can be applied to the particles to reduce undesirable influences of properties of the sample on the indicator substance.

Abstract: Bodies of borosilicate glass with a B.sub.2 O.sub.3 content of less than 13 percent by weight are provided with a microporous layer of a thickness of 5 to 20 .mu.m, and are thus turned into carriers for optical sensors. This process is characterized by the following steps. Thermal decomposition for 5 to 10 days at 500.degree. to 560.degree. C.; removal of the topmost layer of glass to a depth of at least 10 .mu.m in the part of the surface to be rendered porous; leaching of the separated borate phase with diluted mineral acids for a minimum of 2 days at 70.degree. to 98.degree. C.; and after-treatment of the microporous layer, including (a) chemical treatment with concentrated sulphuric acid and concentrated nitric acid for 2 hours at 20.degree. C., and (b) heat-treatment for 10 minutes to 2 hours at 450.degree. to 700.degree. C.

Abstract: An arrangement for the fluorescence-optical measurement of concentrations of substances contained in a sample includes a detector, a light source and a sensor element that includes a carrier element, the carrier element having an indicator layer on a portion thereof and an indicator-free surface, the carrier element being transparent to the radiation used, and having a refractive index which is greater than that of the ambient medium at the indicator-free surface, the light space being positioned such that the transmission of light from the light source to the indicator layer, and from there to the detector, is achieved, at least partially, by total reflection in the carrier element.

Abstract: In an O.sub.2 sensor element which contains a fluorescent indicator substance, a polymerized silicone polymer is used as a carrier material in which the indicator substance is incorporated in solubilized form and in an at least approximately homogeneous distribution. Solubilization of the indicator substance may essentially be performed in analogy to Friedel-Crafts alkylation of aromatics, which will increase solubility of the indicator substance in the polymer carrier without affecting quenching behavior.

Abstract: In a sensor element for determining the O.sub.2 content of a sample, comprising a fluorescent indicator substance which is embedded in a polymer carrier and with which the sample may be brought into contact, a fluorescence extinction sufficiently high for yielding useful measurement results is achieved by the use of plasticizer-compatible polymers as carrier materials which contain plasticizers in addition to the indicator molecules.

Abstract: Fluorescence-optical indicator material is chemically bonded in a network structure permeating a carrier membrane of the sensor element. As this network structure is independent of the membrane and not chemically bonded thereto, the properties of the membrane and the indicator are not affected by the immobilization.