WIT Press

Assuring Comparability Of Results Of Nitrate Determinations In Wastewater: Application Of Metrological Principles


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WIT Press


A. Drolc & M. Roš


In the present paper, a methodology for the establishment of traceability and evaluation of measurement uncertainty of results of nitrate ion determination in wastewater is presented. Nitrate ion was determined using ion chromatography (EN ISO 10304-2, 1996). The necessary relevant information was obtained from the method validation data, the quality control data and equipment calibration certificates. The method of measurement is described together with the measurement equation, selected traceable reference standards and the associated measurement uncertainty. The major sources of uncertainty of the results of measurement were identified and the combined uncertainty was calculated. Identification of the main uncertainty sources represent a basis for target operation for reducing the measurement uncertainty of this determination. Keywords: nitrate, metrology in chemistry, traceability, comparability, measurement uncertainty. 1 Introduction Every year many millions of chemical measurements are made in the EU. It has been estimated that in the industrialised countries measurements and related operations account 4 to 6 % of the gross national product. Measurements are made for important purposes, like the determination of quality of products, estimation of the state of the environment, implementation of environmental regulations etc. That makes these measurements extremely important. But sadly, all too often chemical measurement results are unreliable. The impact of these poor quality measurements on the economic and social live of the EU is enormous. As a consequence, both government and industry are increasingly


nitrate, metrology in chemistry, traceability, comparability, measurement uncertainty.