Historically, the sum parameter “adsorbable organically bound halogens” (AOX) was determined via titration according to EN ISO 9562 or EPA 1650. However, it represents only the sum of chlorine, bromine, and iodine, and does not account for fluorine. With the growing concern over PFAS contamination in the environment, the need to develop a reliable pre-screening parameter for PFAS contamination has emerged. Adsorbable organically bound fluorine (AOF) is such a parameter ideally suited for analyzing water samples.
The newly released ISO 18127 is based on the previously published DIN 38409-59. The methods are suitable for the analysis of various types of water, such as groundwater, surface water, drinking water, aqueous eluates, cooling water, and wastewater. Both standards were developed with support from our Metrohm CIC experts and describe a validated procedure to measure AOX as well as AOF by combustion ion chromatography (CIC). Additionally, the individual contribution of adsorbable organically bound chlorine (AOCl), bromine (AOBr) and iodine (AOI) to the total sum parameter AOX can be specified, which is not possible using titration according to EN ISO 9562 or EPA 1650.
Halogenated organic compounds, also called organohalogens, are molecules that have halogens attached to one or more carbon. While naturally occurring halogenated organic compounds exist, most are man-made. Examples include pesticides, refrigerants, and pharmaceuticals.
Organohalogens and their degradation products can pose serious risks to human health and the environment. Some exhibit mutagenic and carcinogenic properties. Many break down very slowly, leading to their accumulation in the environment, animals, and throughout the food chain.
Monitoring these compounds helps to ensure and maintain appropriate water quality, identify their sources, and assess how effective AOX and PFAS removal techniques are in water treatment processes.