Fast analysis of AOX in waters by CIC

AOX (adsorbable organically bound halogens) is a complex parameter covering the sum of halogenated organic compounds adsorbable on activated carbon. Many of these organohalogens and their degradation products pose serious risks to human health and the environment [1–4]. Monitoring them is essential to ensure appropriate water quality, to trace their sources, or to investigate the efficiency of AOX removal techniques in water treatment processes. Historically, AOX was determined via microcoulometric titration after adsorption of water samples on activated carbon and subsequent combustion (DIN EN ISO 9562 or EPA 1650) [1,2]. By definition based on the technical setup, AOX was comprised of adsorbable organically bound chlorine (AOCl), bromine (AOBr), and iodine (AOI)—but not fluorine (AOF)—as a sum parameter and not its individual fractions. The new DIN 38409-59 describes a validated procedure of adsorption and analysis via combustion ion chromatography (CIC) to determine AOCl, AOBr, AOI, the sum parameter CIC-AOX(Cl), as well as AOF, a monitoring parameter for per- and polyfluorinated alkyl substances (PFASs) currently of emerging global concern.