This European Standard specifies a method for the determination of the mass concentration of water soluble NO3- (nitrate), SO42- (sulphate), Cl- (chloride), NH4+ (ammonium), Na+ (sodium), K+ (potassium), Mg2+ (magnesium), Ca2+ (calcium) in PM2,5 as deposited on filters. This European Standard describes the analytical procedures for determining anions and cations as part of the PM2,5 particulate phase, sample extraction and analysis of anions and cations by ion chromatography. Sampling onto filters will be done in accordance with EN 12341 for PM2,5. 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 up 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 PM2,5 mass concentrations between approximately 1 ?g/m3 (i.e. the limit of detection of the standard measurement method (EN 12341) expressed as its uncertainty) up to 120 ?g/m3. The validated range of the anion and cation concentrations based on the field validation measurements is presented in Table 1. (...) See Annex A for the statistical analysis of the field validation measurements.