DIN 38414-14:2011-08

Polyfluorinated compounds (PFC) are industrially produced, persistent organic compounds, where some or all hydrogen atoms have been replaced by fluorine atoms on the carbon skeleton. Due to their special characteristics and resistance, some of these compounds are used as surfactants in fire-fighting foams, galvanic baths and in the photochemical industry. A large number of chemical products used for impregnating paper, textiles and leather contain these compounds as building blocks of substances, as production-related contaminations or as their degradation products. PFC can enter the water cycle through manufacture, use and disposal and adsorb on suspended matter and sediments in water. During cleaning of wastewater, PFC can adsorb on sludge and lead to contamination of the natural resources soil and ground water during its utilization in agriculture. So far, the compounds perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) have been most frequently examined. These substances are therefore treated as major compounds for the presence of PFC. Longer-chain compounds, such as PFOS and PFOA, accumulate in the blood and liver and have half-lives in the human body of several years. In animal experiments, a number of toxic effects have been observed for these compounds, especially with regard to tumour formation and reproductive toxicity. As a result, apart from a few exceptions, PFOS and compounds derived from it must no longer be used in the European Union or placed on the market. This standard specifies a method for the determination of selected perfluoroalcyl substances in water sediment, sewage sludge, compost and soil. The lower application limit is 10 µg/kg dry mass. Within the framework regarding determination of performance characteristics, applicability of the method on feeding stuff was also validated. The applicability of the method to other compounds not given in the table and other solid materials is not excluded, it shall be tested in individual cases, however. During technical manufacture of perfluoroalkyl compounds by electrolytic fluorination of hydrocarbon starting products, mixed isomers are produced. For this reason, branched isomers, in addition to unbranched isomers, can often occur in the samples to be examined, especially in case of the compounds PFOA, PFHxS and FPOS. Especially in the case of PFOS, significant proportions of branched isomers can occur in environmental samples. As the branched isomers can only be partially separated from each other by chromatography, the method described in this standard specifies a convention for quantification of the total isomer content of each perfluoroalkyl sulfonate or perfluoroalkyl oxylate. The substances are extracted with methanol by ultrasonic-supported extraction from the dried homogenized sample. The extract is diluted with water or purified by solid phase extraction on a weak anion exchanger. Validation and quantitative determination is carried out by high-performance liquid chromatography, coupled with mass spectrometric detection (HPLC-MS/MS).