Most of organohalogens are toxic, carcinogenic, persistent and bio-accumulative. Therefore, these compounds are particularly dangerous for long-term pollution. Different types of organohalogens are used in industry and among other things as pesticide, solvents, cooling fluids. They are also formed as byproducts of pulp bleaching, wastewater disinfection and waste incineration. In order to facilitate monitoring of the large number of partly unidendentified organohalogens in environment, analytical procedures for group parameters have been developed. Three method have been standardized for detection of these compound.
Determination of adsorbable and adsorbed organic halogenated compounds (AOX) is performed by combustion of activated charcoal serving as sorbent for sorption of the above mentioned compounds from waters, leachates and extracts from acidified water sample or determination of these compounds adsorbed on the matrix of the sample. Inorganic halides, which should not be included in the result of determination, are eluted from the sorbent by a solution of NaNO3 or KNO3.
In the case of the determination of organohalides adsorbed on soil, rock and similar matrices activated charcoal is added to the sample suspended in water. Activated charcoal is used to catch the analytes during washing out of inorganic halides by solution of NaNO3 or KNO3.
Determination of volatile, organohalides (POX), represents the compounds capable to be stripped by a gas flow at a defined temperature from the solution or suspension of the sample being analyzed.
Determination of extractable organohalides (EOX) represents a group of halogenated organic compounds with lower polarity able to be extracted from aqueous media with organic solvents with low solubility/polarity in water and containing not a trace of halogens. It is possible to use, in the case of extraction from a solid phase, even solvents with higher polarity and so expand the range to the more polar compounds. Therefore, it is necessary to state always, together with the results, also the solvent used for extraction if it is not strictly stipulated by the used standard. Matrix is represented in this case by vapor of the used solvent and its combustion products (usually only CO2 and H2O) and transport of the sample from the evaporation into the combustion region of the furnace is influenced by volatility of the used solvent.