Estimation of Small Amounts of Fluoride in Body Fluids

Abstract

tied to accommodate this size sample by taking a sample containing 0.72 mg. of calcium, using one fifth the amount of each reagent, and diluting to a volume of 10 ml. Standards are made in the range of 2 to 30 7 of magnesium.

Estimation of a Few Nanograms of Fluoride in Presence of Phosphate by Use of Liver Esterase.

“…Although the semilogarithmie type of plot used by Linde (6) and in the present work for the standard curves is entirely empirical and, under our conditions, not linear over wide ranges of fluoride level, it can be considered linear for practical purposes over satisfactory ranges. In the idealized case of competitive inhibi-tion, a plot of inhibitor level against (1 -h)/h should be linear, where h is the hydrolysis expressed as a fraction of the control value (10).…”

“…Investigation of Enzyme Preparations. Although the beef liver supernatant employed by Linde (6) is quite satisfactory as a source of esterase for the estimation of fluoride, it slowly loses activity and this necessitates continual restandardization and frequently repeated preparations of the supernatant. The preparation of a stable powder was therefore attempted.…”

“…It is probable that most biological materials can be analyzed for fluoride by the present method; however, since certain ions can influence the activity of liver esterase (7), the lower limit of fluoride, which can be determined, will be governed by the amount of sample which can be taken for analysis without significant interference by these ions. Linde (6) has applied his method to blood and urine.…”

“…The assignment of the band near 1025 cm.-1 is a little uncertain but it is probably due to the dextran capsule making up the shell of the bacteria. Another culture grown on a second, but similar media, yielded the Linde (6) appeared to offer the best possibility of attaining the required degree of sensitivity. This method is based on the extraordinary susceptibility of the enzyme lever esterase to inhibition by fluoride, and it is capable of estimating a minimum of approximately 0.1 µg.…”

Thermometric Sensing of Fluoride by Adsorption on Ceramic Hydroxyapatite Using Flow Injection Analysis

“…Some of them rely on the inhibition of an enzyme reaction by fluoride, e.g., using immobilized glucose oxidase with Clark oxygen electrodes, 2 or esterolytic enzymes. 3,4 Other detection methods employ fluoride selective electrodes. 5,6 In the present paper we report the application of commercially available ceramic hydroxyapatite (CHAP) as an affinity matrix for the thermometric detection of sub-ppm levels of fluoride ions in flow injection analysis mode.…”