text: Persistent organic pollutants such as dichlorodiphenyltrichloroethane (DDT), polychlorinated biphenols, dioxins, are all assessed in AOX analysis. Generally, the higher the amount of chlorine in an organic compound, the more toxic it is considered. While there are several biochemical or electrochemical methods to remove organic halides, AOX has been preferred due to its low cost of operation and simplicity of design.
  In a lab, the determination of AOX parameter consists of adsorption of organic halides from the sample on to an activated carbon. The activated carbon can be powdered or granular and adsorbed using microcolumns or a batch process, if the samples are rich in humic acids. Vigorous shaking is often employed in the event of a batch process to favor the adsorption of organic halide on to the activated carbon due to its electronegativity and presence of lone pairs. The inorganic halides that are also adsorbed are washed away using a strong acid such as nitric acid. The carbon with adsorbed organic halide is obtained by filtration, after which the filter containing the carbon is burnt in the presence of oxygen. While combustion of hydrocarbon part of the compounds form CO and HO, halo acids are formed from the halogens. These haloacids are absorbed into acetic acid. Subsequent use of microcolumetric titration, an electrochemical quantification method, provides the AOX content in the sample. Using the dilution ratio, the total AOX content at the location can be estimated. Alternatively, the chlorinated compounds in the sample can be determined by using pentane extraction followed by capillary gas chromatography and electron capture (GC-ECD). The organic carbon that was remaining after the nitric acid purge can be analyzed using UV-persulfate wet oxidation followed by Infrared-detection (IR). Several other analytical techniques such as high performance liquid chromatography (HPLC) could also be implemented to quantify AOX levels. The general adsorption procedure is given below:
  Where  is the activated carbon and  is any organic halide.
  is the organic halide - activated carbon complex that can be filtered out.