Fluorochemicals Flashcards
What are fluorochemicals?
USE: A group of diverse chemicals. Used in several products like food packaging, pans, impregnation
of textiles, firefighting foam and paint.
NAMING:
- Old naming of PFAS: PFC no longer used.
PFAS: Non-polymer is most detected Perfluorinated:
• Basic chemical structure
• Per = ”fully” fluorinated
• Alkyl-group: chain of carbon
• Replaced by fluorine
• That is called ”The tail”
• PFAA perfluoroalkyl acids.
• Carboxylates (PFCAs): Acid-group: the head, carboxylsyre
• Sulfonates (PFSAs): If sulfonic acid on head, then
Polyfluorinated:
• Poly = ”partially” fluorinated
• They are precursorces
• Polyfluorinated not well-undestand
• One or more that is not fluorine attached, tyoicaly H or OOne or more that is not fluorine
attached, typically H or O
• Naming: ”8:2 fluorotelomer alcohol”. 8 = 8 carbon,2 = 2 non-carbon
What is the chemical structure of PFAS?
CHEMICAL STRUCTURE:
• Per-flourochain does not make bonds
• Poly-fluorochain here the CH2 makes bonds
• The polar head: consists of the fluoride. These are electrostatic bounds.
• The carbon chain: is rather non-reactive and inert. The carbon-fluor bond is one of the
strongest bonds which is why the compound is not degraded and hence so persistent.
• The combination of the polar head (fluor) and hydrophobic chain (carbon-chain) is what makes
it a great surfactant. They seek interfaces as they can both repel liquids; they are both hydro
and lipophobic. The fluoride carbon bond are quite resistant to degradation =¿¿¿ persistent.
• It is a surfactant as it has a polar head (fluor) and hydrophobic tail (carbonchain). That is
why it is places at surfaces.
• There are large variations in vapor pressure and water solubilitoes
Explain the Physical-chemical properties of PFAS?
- MW, MP, BP: MW in some range. There are many solids as well as a lot of liquids.
• Dissociation: Several of them are acids.
• Henrys law: there is quite a range.
• Kow: difficult to measure as the compound goes to interfaces.
• Kd and Koc: some sorb to soil and sludge.
• Degradation: they are very persistent compounds. IF degraded then transform to something
more persistent.
• Tokcisity: range of toxicological observations.
Talk a bit about PFAS in relation to Transport.
- For PFAS the compounds can be transported in several ways as part of macroscale transport.
• First, PFAS is transported mainly trough a carrier, which in this case is consumer products.
These consumer products are things that we know from our everyday life as Teflon pans,
clothes, food packaging etc. and these are sold all over the world, which is also why it is
considered a part of macroscale transportation.
• Second, PFAS are also transported via a biological carrier. As mentioned the compounds can
bioaccumulate in biota (not found in the lipids but other places).
• Also a PMT compound. Used in firefighting foam and ends in slud
Talk a bit about PFAS in relation to distribution.
*if PFAS ends in the human body it will mainly distribute in lungs, stomach and human tissue.
It will bind to the protein in the blood, which connects to the liver and the kidney. Here they
will bind as they are rich in protein and as we know they associate to surfaces. One would
expect that they would bind to the intestines, however, a lot of material is passing through so
perhaps not.
• It is generally hard to measure the logkow for fluorochemicalcs as they are both hydro- and
lipophobic. They don’t want to stay in either water nor lipo-suspensions, making it hard to
measure, therefore it is not very meaningful to do. It will mainly stay in the interphase in
doing so, hence it is technically difficult to do.
• Instead one could look at the affinity of fluorochemicals binding to protein. The challenge here
is that there is a lot of proteins, so one need to have some kind of standardization as it is
analytically not easy.
• Usually one would look at logkow, but this does not make sense here. In this way these
compounds challenges how we look at them
