Evaluation of combined measurement uncertainty of the determination of Mn content in sediment samples

Combined uncertainties of an analysis of elemental content of sediment samp les were evaluated. A monitoring system has been designed and implemented f or the characterization of the environmental conditions of Lake Balaton in Hungary. Sediments samples were collected and an acidic digestion method wa s used to determine the concentration of elements. For the calculation of t he result of each measurement three different approaches were considered, n amely a.) the calculation of the result using a calibration curve and estim ating the confidence limit by the Student t-distribution, b.) calculation o f the combined uncertainty and c.) estimation of the sampling errors using the transport and field blanks. The latter approach gave the most reliable result since it included all the parameters which had to be considered rega rding sampling and sample handling, and measurement. Determination of acid soluble Mn content in sediment samples has been chosen as an example, and t he combined uncertainty is calculated using blanks for sampling.