Estimation of the measurement uncertainty of a gravimetric analytical procedure applied in fluvial hydrosedimentology - A didactic example for metrology in chemistry education in technical and undergraduate courses

Abstract

The measurement uncertainty is fundamental to assess the 'quality' of the results of any experiment. The measurement result with the corresponding uncertainty statement ensures its fitness for purpose by giving a measure of the confidence that can be placed on the results. This paper presents a detailed and didactic evaluation of the uncertainties for suspended sediment concentration determined by a gravimetric analytical method by filtration and for the river solid discharge using both the variance propagation law and its particular cases for sums (subtractions) and multiplications (divisions). The sources of uncertainties considered to estimate the uncertainty of the suspended sediment concentration were the weighing (resolution and calibration of the balances), the resolution of the conversion factor, the intermediate precision of the whole analytical procedure and the repeatability precision due to the direct measurements. The major uncertainty contributions for the suspended sediment concentration uncertainty were the intermediate precision and weighing of the samples.