A new and improved gas chromatographic method for the determination of fluoride in plasma and faeces.

A method is described that extracts fluoride selectively as trimethylfluorosilane using carbon tetrachloride and trimethylchlorosilane . Drawbacks of other methods as well as advantages of the proposed method are discussed. The method is directly applicable to plasma and faeces samples, has a short gas chromatographic run time due to the use of a backflush technique and is suitable for automation. Its lowest quantifiable limit for plasma and faeces is 10 micrograms/l and 1 microgram/g fluoride respectively, using 1.0 ml or 1.0 g samples. Preliminary pharmacokinetic parameters of fluoride obtained in two subjects are reported.