UNCERTAINTY BUDGET FOR PRIMARY ELECTROLYTIC CONDUCTIVITY MEASUREMENT COMPARING DIFFERENT METHODS

摘要

In 2007, the Chemical Metrology Division (Dquim) from National Institute of Metrology, Standardization and Industrial Quality - Inmetro, established the primary system of electrolytic conductivity (EC) measurement. The main use of this system is to provide reliability and traceability to the EC measurements in Brazil, since its measurement is very important mainly for determining the purity of water. In order to show comparability and capability in primary EC measurement, Inmetro has participated in the key-comparison organized by Consultative Committee for Amount of Substance (CCQM) called CCQM-K36.1 to measure the EC in two solutions: one with a nominal value of 0.5 S m~(1) and the other, 5 mS m~(1). This work aims to present a comparison among the values of the uncertainty results from primary EC measurement in the solution of 0.5 S m~(1) obtained by using the methods of ISO GUM, Kragten and Monte Carlo simulation. In addition, this work will also present an evaluation of the uncertainty related to all relevant sources in the uncertainty budget for EC measurement by using the primary EC system from Inmetro. Moreover, this study has the purpose to show the main points which should be focused on in order to improve the process of primary EC measurement, when needed.