DETERMINATION OF FLUORIDE IONS BY SINGLE COLUMN HIGH PRESSURE ANION CHROMATOGRAPHY IN DENTIFRICE PREPARATIONS AND BODY FLUIDS: SALIVA AND BLOOD SERUM

Abstract

Fluoride ions are commonly used as anticaries agents in dentifrice preparations. However, when the fluoride level exceeds the recommended limits some fluorosis may be noticed. This paper focuses on the single column ion chromatographic determination of fluoride using conductometric detection. Chromatography was achieved on a low capacity anion exchange column, Hamilton PRP-X100 150 × 4.1 mm, 10 μm, with a low conductivity mobile phase consisting of 4 mM p-hydroxybenzoic acid and 0.5 mM sodium benzoate (pH 9.0 adjusted with 1 N NaOH) at a flow rate 1.8 mL/min. For the quantitative determination, peak height was used, while in some cases bromide can be used as internal standard (suggested concentration 15 mg/L). A rectilinear relationship was observed up to 30 mg/L. The limit of detection (S/N = 3) was 1 ng, while the limit of quantitation (LOQ) was 5 ng at 0.1 μS, when 50 μL of the samples were injected onto the analytical column. The time of analysis is less than 3.5 min. The statistical eval-uation of the method was examined performing within-day (n = 8) and inter-day calibration (n = 8) with RSD values rang-ing from 2.6 to 5.2 and from 7.1 to 11.7 respectively. The applicability of the method was demonstrated in the analysis of sodium fluoride dentifrices: lozenges, toothpastes, mouth wash solutions, as well as in body fluids: saliva and blood serum. Recovery of fluoride ions in spiked body fluid samples ranged from 91.7 to 110.1%.