Measurement of total and diffusible serum fluoride

Abstract

This article describes a technique for the measurement of total and diffusible F content of serum, at clinical significant concentrations of F (1-10 microM). The proposed procedure avoids the interference of unknown serum components with the ion-specific electrode. Sample F is concentrated fivefold through distillation of hydrofluoric acid (Taves' method). Ionic fluoride is presented to the electrode in a simple solution at concentrations within the linear response of the electrode. Average recoveries of F from serum or its ultrafiltrate were 96+/-7% (21%) and 97+/-12% (53%) (mean+/-SEM [CV]), respectively. With four replicates of each sample, the technique produce within-run standard deviations of 0.6 microM and 2.2 microM at 1 and 10 microM F, respectively. Total precision assessment gave standard deviations of 0.6 microM and 2.6 microM at 1 and 10 microM F, respectively. The fasting serum F levels of normal climacteric women, 45 to 65 years, showed an asymmetric distribution. The data obtained started at the detection limit of the technique (0.1 mM). The 75 percentile was 1.85 microM for total and 0.5 microM for diffusible F. In patients (n = 25) treated with NaF (30 mg F/day) the fasting levels of total serum F (4.5 +/-1.7 microM) did not differ from those of diffusible F (4.2+/-1.5 microM). In patients (n = 50) treated with sodium monofluorophosphate (15 mg F/day) the fasting levels of total and diffusible serum F were 6.5+/-1.7 microM and 0.5+/-0.03 microM, respectively. In conclusion, this paper establishes the presence of two fractions of serum fluorine: diffusible and nondiffusible (or protein bound) and describes a technique for their clinical estimation. In untreated subjects and in patients receiving NaF, the former fraction contains ionic fluoride. In patients treated with MFP, diffusible serum fluorine is composed by ionic fluoride and low molecular weight, peptide-bound, acid-labile fluorine.

Comparison of fluoride effects on germination and growth of Zea mays, Glycine max and Sorghum vulgare

“…Subsequently, the sodium hydroxide trap is adjusted to pH 5.5 with 17.5 mol L −1 acetic acid. 22 Standards in the range of 0.8 to 19 ppm were simultaneously processed. Results are expressed as parts per million of dry weight of the sample.…”

Effect of Fluoride on the Secretion of Insulin in the Rat

“…Fluoride concentrations in plasma were measured with an ion specific electrode (94-09, Orion Research Inc., Cambridge, MA) [5]. Before measurement, inorganic fluoride was isolated by means of the room temperature diffusion method of Taves [6].…”

Intestinal Absorption of Fluoride at High Luminal Concentration of Fluoride

“…Blood was drawn at 0, 30, 60, 120, 240 and 1440 min after the dose. Urine was collected during the subsequent 24 h. Total fluoride (urine and plasma) was measured as reported elsewhere [7]. Pharmacokinetic parameters: k e (rate constant of elimination), C max (maximum concentration), T max (time when plasma concentrations reach the highest value) and AUC (the area under the curve of fluoremia as a function of time) were calculated with a computer program [8].…”

“…Treated animals received 40, 80 or 160 µmol of fluoride/day in 1 ml of water (four animals per group). The fluoride contents of plasma, ashes of feces and bones were measured as described elsewhere [7].…”

“…Extraction of samples and mixing of the filling solution was achieved withdrawing and refilling the duodenal sac with a syringe. Fluoride was measured in each sample [7] and the data was used to estimate the rate constant of fluoride absorption (ЉkЉ).…”