Spectroscopic determination of fluoride from groundwater using eriochrome black t (ebt) as spectrometric reagent: a method development

Abstract

Fluoride health problem is a global issue as a result of groundwater use. Thus, trace level fluoride analysis is vital to take appropriate measures upon fluoride level in drinking water. Potentiometric method is an effective analytical technique for the determination of fluoride ion in various samples matrics. Spectroscopic methods are also found important to quantify fluoride levels from water, however, several factors hinder its easier determination. Among the bottlenecks, the use of expensive chemicals and tedious steps in preparing chemicals as well as toxicity of chemicals used (e.g., SPANDS method) are to mention few. In this study, spectrophotometric based method was developed for the determination of fluoride from groundwater using Eriochrome Black T (EBT) as spectroscopic reagent. Experimental parameters affecting determination of fluoride including ligand type, reaction time, pH and ligand to metal ratio were assayed and the optimum conditions were established. Calibration curve was constructed by preparing different standards of fluoride at seven concentration levels. The obtained calibration curve has good linearity with a coefficient of determination (R2 = 0.9997). The limits of detection (LOD) and quantification (LOQ) were 0.19 and 0.64 mg/L, respectively. The precision studied in terms of intra-day and inter-day at two concentration levels showed %RSD values that were less than 7% in both cases. Applicability of the method was investigated by analyzing groundwater samples and demonstrated satisfactory recoveries which were 111.4 and 110.6 for 0.5 and 1.5 mg/L concentrations, respectively. The developed spectrophotometric method could be used as attractive alternative for the determination of fluoride from groundwater.