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.