Comparison of results of ion analyses in extracts from samples obtained with Annular Denuder Systems
Vergelijking van analyseresultaten in extracten afkomstig van monsternemeningen met Annular Denuder Systemen
Mennen MG , Hoek G , Cottaar F , Neele J
RIVM Report 222702001
Samples obtained with an Annular Denuder System (ADS) have been analysed by the Agricultural University of Wageningen and the National Institute of Public and Environmental Protection on sulfate, nitrite, nitrate, ammonium and hydronium. The ADS is used by both institutes to determine concentrations of acidifying gases and aerosols in ambient air. After sampling these gases and aerosols are dissolved in deionized, distilled water and concentrations of the corresponding ions are measured. For most of the ions different analytical methods used by the Agricultural University of Wageningen on one hand and the National Institute of Public Health and Environmental Protection on the other. In this examination samples have been analysed by both institutes for comparison. It has been set up both in order to examine the quality of the analysis methods and to determine, whether the concentrations of gases and aerosols measured by both institutes with their ADSs can be interchanged in further research. Good agreement was found for sulfate, ammonium and hydronium, Concentrations of nitrite measured by the Agricultural University of Wageningen were 10 times lower than those determined by the National Institute of Public Health and Environmental Protection. This difference can be presumably attributed to a calibration or a calculation error. After correction for this error the agreement was rather good. Nitrate concentrations from denuder samples showed relatively large differences, which may have been caused by instabilities in the corresponding solutions. Due to this differences the corresponding nitric acid concentrations can not be interchanged. Differences in nitrate concentrations from filter samples were acceptable.