Determination of chloride and fluoride in elemental boron using ion chromatography with suppressed conductivity detection

An accurate method based on combination of microwave assisted digestionsuppressed ion chromatography is proposed for the determination of fluoride and chloride in nuclear grade enriched boron (B10). The digestion of the boron matrix is carried out in closed vessel microwave assisted digestion using hydrogen peroxide and dilute nitric acid. By using the microwave assisted approach, the digestion would be carried out using an acid quantity which is less by a factor of 3.6 and thus the overloading of the IC column and base line perturbations are avoided. The regeneration of nitric acid takes place via the reaction of evolved NO2 with water. Parameters optimized during this study to get quantitative recoveries of chloride and fluoride were; hydrogen peroxide & nitric acid concentration, microwave power, irradiation time and amount of the sample. Chromatographic performances of two analytical columns (IonPac AS15 and IonPac AS20) were compared for the separation and quantitative determination of fluoride and chloride in the resulting high nitrate matrix. Method detection limits for fluoride and chloride were 8 and 15 mg kg-1 respectively while the relative standard deviation (RSD) was less than 10% in most of the cases. Comparison of data obtained by a well known spectrophotometry methods like mercury thiocyanate-Fe3+ and ion selective electrode were employed to verify the accuracy of the proposed method. The proposed method is in agreement with green chemistry protocols, when digestion carried out by using dilute nitric acid that minimizes laboratory waste. © 2016 Universal Research Publications. All rights reserved