Measurement uncertainty in the pH measurement procedure

A measured value without even an approximate knowledge of the uncertainty is worthless. The uncertainty is part of every measured value and specification of the uncertainty is part of every analytical procedure. The uncertainty makes the value independent of its origin. The basis for estimation of the uncertainty is the "Guide to the Expression of Uncertainty in Measurement". For some procedures, however, for example pH measurement, several problems arise in practice. This article describes a practical and inexpensive way of calculating the uncertainty of pH values.