Intercomparison of Analytical Methods within the European Monitoring and Evaluation Programme (Emep)

Abstract

Publisher Summary This chapter discusses the plan, prepared by the Chemical Centre, for intercomparison of the analytical methods to be used in the European Monitoring and Evaluation Program (EMEP). The intercomparison of the methods is an essential part of the project. The plan for the intercomparison is based on the previous experience obtained in interlaboratory tests conducted within the OECD project “Long Range Transport of Air Pollutants” (LRTAP). Information about the reproducibility of the analytical methods employed within the LRTAP was necessary for evaluation of the chemical data. Series of samples were distributed to the participating laboratories for analysis, and the mean concentrations and standard deviations were determined. The chapter explains the results of an intercomparison study of methods for determination of sulphur dioxide in the hydrogen peroxide absorbing solution, and of sulphate and strong acid determination in precipitation. All these samples were synthetic. One laboratory applied a nephelometric method for the determination of sulphate, and two were using a titrimetric Thorin method. All the others used the spectrophotometric Thorin method, which is recommended in the manual. The results show a satisfactory agreement for the determination of sulphur dioxide and of sulphate in precipitation. Some of the samples of strong acid gave large standard deviations, but these were caused by a few outliers.