Fluoride in biological material

H.B. Li, F. Chen, A highly sensitive fluorimetric method for the determination of fluoride in biological material with AP -calcein complex, Fresenius J. Anal. Chem. 368 (2000) 501-504. 

D. Klockow, J. Auffarth, C. Kopp, A catalytic kinetic method for the determination of traces of fluoride in biological material. Anal. Chim. Acta 89 (1977) 37-46. 

Determination of Fluoride in Biological Material by Cas Chromatography Pharm. Tijdschr. Belg. 45(9) 177-179 (1968) CA 70 84840e... 

Determination of Fluoride in Biological Materials by Means of Gas Chromatography... 

P. Venkateswarlu, Evaluation of analytical methods for fluoride in biological and related materials, J. Dent. Res. 69 (1990) 514-521. 

The method based on the use of DAM has been applied for determining titanium in biological materials [11], silicate rocks [32,99,100], cast iron and steel 33], molybdenum and tungsten [6,18], vanadium [18], zirconium, hafnium, and niobium [101], lithium fluoride [102], nickel, aluminium, and molybdenum alloys [11], and ferrotitanium [103]. Titanium was determined in aluminium alloys with the use of DAM in the presence of SnCh [35,104]. 

Nevertheless, fluoride does lead to a reduction in the solubility of hydroxyapatite in aqueous solution, even in the absence of trace levels of fluoride in solution, and hence can be seen to have an effect in the solid state as well [57], Apatites are complex and diverse materials which have the general formula Caio(P04)eX2 (X = F, Cl, OH) and they represent a crystallographic system, in which there can be considerable replacement of species. Thus, with little or no change in the dimensions of the crystal lattice, there can be exchanges of OH for F, Ca + for Sr +, and PO4 for CO and all of these are known to occur in biological systems. Natural hydroxyapatite, for example, is often partially carbonate substituted [58]. 

Traces of fluoride can be separated from aqueous solutions by extraction with triethylchlorsilane in m-xylene The conditions were optimized and co-precipitation (for enrichment) reactions were tested Adsorption on hydroxyl apatite was found most suitable. From acidified solutions of biological materials fluoride was selectively extracted with a solution of trimethylchlorsilane in benzeneOrganic material or blood was destroyed by heating with hydrochloric acid and hydrogen peroxide in a closed distilling apparatus. The resulting distillates were extracted by triethylchlorsilane in tetrachloroethylene ... 

Morsches, B. and Tolg, G. (1966). Method for determination of trace elements in limited amounts of biological materials, Fres. Z. Anal. Chem. 219,61-68 Munksgaard, E.C. and Bruun, C. (1973). Determination of fluoride in superficial enamel biopsies from human teeth by means of gas chromatography. Archs. Oral Biol. 18, 735-744... 

The fluoride selective electrode is routinely used for flie determination of fluoride in drinking water, industrial effluents, sea water, air, aerosols, flue gases, soils and minerals, urine, serum, plasma, plants, and other biological materials. The following discussion focuses on flie development of analogous techniques for flie determination of fluorine in hydrocarbons. 

Two methods were examined for digestion of biological samples prior to trace element analysis. In the first one a nitric acid-hydrogen peroxide-hydrofluoric acid mixture was used in an open system, and in the second one nitric acid in a closed Teflon bomb. The latter method was superior for Ge determination, however, germanium was lost whenever hydrogen fluoride had to be added for disolving sihcious material. End analysis by ICP-AES was used for Ge concentrations in the Xg/g range13. 

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