Sciencemadness Discussion Board - F- From Tap Water?

F- From Tap Water?

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blogfast25 - 22-2-2013 at 06:55

"Fluoride ions form stable, colorless complexes with certain multivalent ions, such as (AlF6)3-, (FeF6)3-, and (ZrF6)3-. Most colorimetric methods for the determination of fluoride are based on the bleaching of colored complexes of these metals with organic dyes when fluoride is added (WHO 1984). The degree of bleaching is determined with a spectrophotometer, and the concentration of fluoride ions is assessed by comparison with standard solutions. In EPA Method 340.1, the sodium 2-(parasulfophenylazo)-1,8-dihydroxy-3,6-naphthalenedisulfonate (SPADNS) reagent is used, and the color loss is measured at 570 nm (EPA 1998c). In EPA Method 340.3, the red cerium complex with alizarin complex one turns blue on the addition of fluoride (EPA 1998c)."

When fluoride ions are tightly complexed they don't behave like fluoride ions. That also why the menacing looking K3Fe(CN)6 can be used as a food additive: it reacts neither as CN- nor as Fe3+.

NEXT!

Morgan - 22-2-2013 at 11:39

Methods for Determining Parent Compounds and Degradation Products in Environmental Media
"Methods are available for determining fluoride levels in
environmental samples. Methods determine the fluoride concentration and not the particular fluorine-containing compound. Therefore, analytical methods do not distinguish between parent compound and degradation product. The ISE
method is the most common method for measuring fluoride in environmental samples. It is a convenient, sensitive, and reliable method, but fluoride ions must first be released from any matrix and rendered free in solution."
http://www.atsdr.cdc.gov/toxprofiles/tp11-c7.pdf

“It is not clear if current analytical techniques are capable of detecting whatever species exist under actual drinking water conditions, and such knowledge is critical for the formulation of sound policy and regulation. Table 6 lists species that may exist in fluoridated water systems.”
http://www.enviro.ie/Rebuttal_June_2012.pdf

Uptake of fluoride by tea plant (Camellia sinensis L) and the impact of aluminium
"The concentrations of fluoride in the leaves were significantly (P < 0.05) increased by 19.1% or 37.7% when 18.5 µmol l−1 Al or 74.1 µmol l−1 Al respectively was included in the uptake solution, compared with the control without Al during an uptake period of 22 h. Similarly, Al application (100 mg kg−1) to soil led to significantly higher fluoride concentrations in mature leaves and new shoots (one bud with three leaves).
http://onlinelibrary.wiley.com/doi/10.1002/jsfa.1546/abstrac...

Sorption and Desorption of Fluoride in Soil Polluted from The Aluminium Smelter at Årdal in Western Norway
"The B-horizons sorbed considerably more F than the Ah-horizons, due to higher content of Al-oxides/hydroxides."
"Continued deposition of F may increase the availability to plants and soil organisms."
http://link.springer.com/article/10.1023%2FA%3A1004900415952...

The other day I came across this up because I noticed my purple fluorite crystals smelled like sulfur when I rinsed them off. I post this just as an aside.
"Wanting more proof, Kraus looked for F2 using mass spectrometry, but could not find it and says it ‘must have reacted with parts of the mass spectrometer before we could detect it’."
"The analysis by NMR seems fine, although the identification by smell does harp back to a bygone age of chemistry!’ He adds that Kraus’s discovery will change many people’s perception of fluorine’s natural occurrence. ‘The opening line in many chemistry books’ chapters on halogen chemistry needs modification," he says.
http://www.rsc.org/chemistryworld/2012/07/fluorine-finally-f...

Morgan - 22-2-2013 at 12:33

A relatively small but quirky source of fluoride.

"Arctic krill contain exceptionally large amounts of fluoride, (mg/kg dry weight): whole animal 1000, muscle 70; and exoskeleton, 2000." (Page 162)
http://books.google.com/books?id=UTva4Zbh_8UC&pg=PA162&a...

http://link.springer.com/article/10.1007%2FBF00286823?LI=tru...

New Scientist
"Minced krill ended up in sausages and soup, but it is a poor raw material for the food industry because it is very alkaline, it does not bind water and it emulsifies fats poorly."
"More oddly, it sometimes ignites spontaneously for no known reason and chickens that eat large amounts of it produce eggs with red yolks."
http://books.google.com/books?id=hV72KUegEHIC&pg=PA39&am...

Penguin bones
Krill-eating adélie penguins (Pygoscelis adeliae) reached equilibrium concentrations in the order of 10000 mg F/kg d.w. in femur.
http://link.springer.com/article/10.1007%2FBF00259206?LI=tru...

"Although bones of Adelie penguin (Pygiscelis adeliae) and skua (Catharacta maccormicki) showed exceptionally very high F concentration in the range of 832 to 7187 mg kg(-1), their radiographs did not show any evidence of skeletal fluorosis. The possible reason and geochemical aspects of F in Antarctica region are discussed."
http://www.ncbi.nlm.nih.gov/pubmed/14740990

"By the use of an ion-selective electrode, the fluoride concentration in these samples were found to be higher than that normally occurring in any mammalian species, ranging from 4340 to 18 570 ppm. The positive correlation observed with age, along with high fluoride concentrations found in krill taken from the stomachs of these whales, indicated a probable bioaccumulation of fluoride from dietary sources."
http://www.sciencedirect.com/science/article/pii/01411136919...

[Edited on 22-2-2013 by Morgan]

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