Column preconcentration of iron(III) with an ion pair of 1,2-dihydroxybenzene-3,5-disulfonate and benzyldimethyltetradecylammonium ion supported on naphthalene using flame atomic absorption spectrometry

Abstract

A solid material consisting of an ion pair produced from disodium 1,2-dihydroxybenzene-3,5-disulfonic acid (Tiron) and benzyldimethyltetradecylammonium (BDTA) chloride supported on naphthalene in a funnel with a glass tube and tip provides a simple, rapid and selective method for preconcentrating iron from biological samples. Iron(III) reacts with Tiron to form a water soluble, coloured, chelate anion. The chelate anion forms a water-insoluble iron(III)–Tiron–BDTA complex on the surface of Tiron–BDTA–naphthalene adsorbent packed into a column. Iron is quantitatively retained on the naphthalene in the pH range 6.0–9.0, at a flow-rate of 1 ml min^–1. The metal complex and naphthalene column are dissolved with 5 ml of dimethylformamide (DMF) and the absorbance was measured using flame atomic absorption spectrometry (FAAS) at 248 nm. The calibration graph is linear over the concentration range 0.5–20 µg of iron in 5 ml of the final DMF solution. The sensitivity for 1% absorption was 0.078 µg ml^–1(0.165 µg ml^–1 for the direct FAAS method from the aqueous solution). The method has been utilized for the determination of iron in standard reference materials of mussel and chlorella.