Uncertainty estimation of online measurement and manual sampling in water quality measurements

In this work, the measurement uncertainty of online environmental measurements was compared to the overall measurement uncertainty of manual sampling and laboratory analysis. The measured parameters were pH, turbidity, suspended solids and COD. The measurement results and uncertainty of online measurements were compared with the uncertainties given by two accredited analysis laboratories. The uncertainty related to sampling for the laboratory analyses was also estimated. The uncertainty estimation for online measurements was carried out according to Evaluation of measurement data - Guide to the expression of uncertainty in measurement (JCGM 100:2008, GUM 1995 with minor corrections). The sampling uncertainty was estimated according to Nordtest TR 604 Uncertainty from Sampling guide