Журнал экосистемы и экографии

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Comparison of different Total Ionic Strength Adjustment Buffer Compositions for Determination of Low Level Fluoride in Environmental Water Samples with Fluoride Ion Selective Electrode

Forsido TT* , Ndibewu P

Fluoride content of environmental water samples collected from the vicinity of Pilanesberg National Park was determined using a Fluoride Ion Selective Electrode (F-ISE). Different Total Ionic Strength Adjustment Buffers (TISABs) EDTA, CDTA, citrate and acetate buffers, were compared for their effectiveness in releasing fluorine into the solution in its ionic form, by adjusting the pH and ionic strength of the solution, as well as by chelating polyvalent cations present in the samples. Nine water samples were collected from different sites around the park, where there is a decommissioned fluorspar mine, and an extinct volcano for fluoride content. Quantification was carried out by means of multipoint calibration covering the range of interest in all treatments. The fluoride concentration was calculated using the Nernst equation with values obtained from the calibration graph. It was found that CDTA and EDTA buffers were the best TISABs as they produced a better linearity, slope and recovery in that order, whereas the other acetate also produced better parameters and results than the untreated water samples.