Perfluorinated compounds (PFCs)
Feb 9, 2015
Polyfluorinated compounds are part of persistent organic environmental pollutants exhibiting bioaccumulation potential. The compounds are composed of a hydrophobic alkyl chain with variable carbon number (typically C4 to C16) and by a hydrophilic part. The hydrophilic part can be wholly or partially fluorinated. If fully fluorinated, then the molecules are referred to as perfluorinated compounds (PFCs).
For partially fluorinated compounds, position and number of fluorines characterize the substance.
PFCs include several basic classes of compounds. They are:
- Perfluoroalkylcarboxylic acids (PFCAs)
- Perfluoroalkylsulfonic acid (PFASs)
- Perfluorinated sulfoamidoethanols (FOSEs)
- Perfluorinated sulfonamides (FOSAs)
- Fluorotelomer sulfonates (FTSS)
- Fluorotelomer alcohols (FTOHs)
Fluorine is in ionic form one of the most reactive elements. Bound fluorine is very stable. For this reason, fluorocarbons are completely stable in air (even at temperatures exceeding 150 ° C), incombustible, resistant to strong acids, bases, oxidizing agents and photolysis. Through these unique physicochemical properties PFCs found application in a variety of industries. They repel water and oil, and therefore a large proportion of these substances is used for the protection of consumer products. Previously these substances found application in surface treatment of carpets, fabrics, leather and paper, the production of coatings and additives for paints, production of detergents for domestic and industrial applications, and the production of pesticides and insecticides.
In 2000 the US company 3M, the world's leading manufacturer of PFOS, ceased manufacturing. Currently PFCs are still employed as additives in fire-fighting foams and hydraulic fluids, in photographic industry, in production of metallized articles and photolithography. However, their use is being gradually reduced.
PFCs present amphoteric character and the long fluorinated chain is responsible for their persistence and accumulation in sediments and biota. It is not just food that is important to human exposure but packaging like pizza boxes or bags of popcorn also play a role. After entry into the body, adsorption and distribution occur mainly in the liver and body fluids which binds the protein component of tissues. Substances are usualy excreted from human body gradually, however due to the simultaneous exposure there is virtually no chance that they can be completely eliminated during life. It is estimated that human body expels half of the amount of PFOS received in about 9 years and PFOA in 1-3 years. The main source of PFOA for consumers comes from food and drinking water. PFOS bio accumulates and its concentration is gradually increasing with the current half-life in the human body being about 5 years. PFOS is not a classic Persistent Organic Pollutant (POP), it does not store in the fatty tissues, but instead binds to proteins. For this reason, it accumulates in organs such as the liver, kidneys, brain and spleen.
The presence of PFOS was found in organisms like birds, fish and mammals, through this it is clear that this substance can penetrate into the food chain. In 2008, the European Food Safety Authority (EFSA) recommended the EU Member States monitor food for two important representatives of PFCs, namely perfluorooctanoic acid (PFOA) and perfluorooctansulfonate (PFOS) to estimate human exposure to these substances. EFSA for PFOS sets tolerable daily intake (TDI) at 0.15 mg / kg bw / day and for PFOA at 1.5 micrograms / kg body weight / day.
EU Member States monitor the concentration of perfluorooctansulphonic acids and other derivatives (PFCs) in surface waters under the directive of the European Parliament and Council Directive 2000/60/EC (amendment 2013/39/EU).
ALS Laboratory performs the determination of these substances by using modern equipment consisting of ultra-performance liquid chromatography coupled with mass spectrometry (LC-MS/MS). A team of experienced analysts optimized the procedure based on the method of direct injection with addition of labelled extraction standard. Currently, the method enables the determination of 17 perfluorinated substances with a quantification limit of 0.01 µg / L for each analyte. The method is fully validated and accredited.