Statistical evaluation of uncertainty for rapid tests with discrete readings - examination of wastes and soils

In the course of the colorimetric determination of analytes using a procedu re with discrete readings the measurement uncertainly cannot be calculated in the normally practiced manner. The basic principle of the analytical met hod used is a stepwise and non-equidistant reading. Based on the fact that half a step can be estimated, a calculation of the measurement uncertainty for the 95% confidence level is possible; this is needed to allow a reliabl e decision of whether a critical value is exceeded or not.