TECH Brief 10 – Estimation Combined Uncertainty Burette Volume Automated Titrator

Described is a procedure to estimate the combined measurement uncertainty in the volume delivered by an automated titrator. Typically, the combined volume measurement uncertainty from a titration is required in the modelling approach for the estimation of the expanded uncertainty of a titrimetric method. This technical brief provides an example of the estimation of measurement uncertainty derived from the internal volume, the uncertainty in filling to calibration mark and uncertainty in solution temperature differing from the calibrated temperature.

With a standard ‘manual’ burette, the internal volume uncertainty is marked by the manufacturer onto the burette along with the nominal volume. However, automated titrators may not have a stated internal volume uncertainty for the burette, but a rather give a stated uncertainty on the burette diameter. Therefore, the uncertainty in the volume of the burette of an automated titrator is calculated from the diameter of the radius of the burette.