This European Standard specifies a method for the determination of the mass concentration of water soluble NO3-, SO42-, Cl-, NH4+, Na+, K+, Mg2+, Ca2+ in PM2,5 as deposited on filters. This European Standard describes a measurement method which comprises sampling of anions and cations as part of the PM2,5 particulate phase, sample extraction and analysis of anions and cations by ion chromatography. NOTE 1 Alternatively, cations, excluding ammonium, can be analysed by inductively coupled plasma optical emission spectrometry (ICP-OES). Ammonium can also be analysed by photometry or conductometry. This European Standard can be used for the measurements of anions and cations as required by Directive 2008/50/EC. The method does not take into account the possible losses during sampling due to evaporation. NOTE 2 NO3-, Cl-, NH4+ are part of the volatile fraction of PM2,5, and the concentrations determined using this standard can be used as minimum values for the concentrations of these ions in PM2,5. NO3-, NH4+, Cl- are usually 0 % to 30 % underestimated due to evaporational losses from the filter during sampling. This European Standard may be used at rural and urban background sites and road sites that are in accordance with the siting criteria of Directive 2008/50/EC. This European Standard is applicable to the measurement of anion/cations in PM2,5 samples corresponding to mass concentrations between approximately 1 ¼g/m3 (i.e. the limit of detection of the standard measurement method (EN 12341) expressed as its uncertainty) up to 120 ¼g/m3.