Determination of fluorine and iodine in biological materials

Fluorine and iodine were determined in some biological reference materials. Radiochemical neutron activation analysis was used for iodine and ion-selective potentiometry for fluorine. The two elements were separated from the matrix elements by pyrohydrolysis in the presence of vanadium(V) oxide. The volatile compounds were absorbed in sodium hydroxide solution for the determination of fluorine and in acidic silver nitrate solution for the determination of iodine. This method gives low detection limits with small sample sizes.