Development of a flow manifold for Fe(III) ion determination with a fluoride ion-selective electrode

Continuous-flow (CF) and flow-injection (FI) analysis using the fluoride ion-selective electrode (FISE) as detector have been investigated. The measurements were performed in a home-made cell under appropriate flow conditions (2.86 or 3.45 ml min−1, 0.2 ml samples, 10−6 M sodium fluoride). The calibration graph was obtained by plotting the signal height versus concentration of iron in the range of Fe(III) concentration from 10−5 to 10−1 M in acetate buffer (pH 2.8 or 3.4). In all described procedures, the range of linear response extends to the Fe(III) concentration from 1×10−3 to 1×10−1 M, with detection limit 9×10−5 M. The effect of double-line, two-line flow manifold and CF was investigated and discussed.