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: Quality control of an analyzing system that includes a portable analyzer with insertable single-use cartridges whose sample chamber contains optical and/or electrochemical sensors is accomplished by bringing the sensors in the single-use cartridge into contact, or are in contact with, a calibrating and/or conditioning medium, the calibrating and/or conditioning medium exhibiting chemical and/or physical parameters which influence the characteristic of at least one of the sensors. Just before a sample is measured, the sensors are contacted with a quality control liquid which is identical with the calibrating and/or conditioning medium within a predetermined desired range of accuracy for the sample components to be measured, as regards the chemical and/or physical parameters influencing the characteristic of at least one sensor during calibration and/or conditioning. The instantaneous control values obtained on the basis of the calibration values are subsequently compared to known target control values.

Abstract: A system for determining the value of a compositional parameter of blood, including a sensor for producing a signal related to the value of the compositional parameter. A computer analyzes the signal and produces an output representing the value of the compositional parameter of blood. There is a delayed response in the system such that the signal has a time-varying waveform that varies from an initial value to an equilibrated value. The equilibrated value is predicted by detecting the occurrence of an inflection point and then computing an estimate of the equilibrated value based upon the assumption that the waveform varies exponentially from the inflection point to the equilibrated value.