High-performance liquid chromatographic separation of iron, bismuth, indium and thallium by pre-column chelation with 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulphopropylamino)phenol

Abstract

The reversed-phase high-performance liquid chromatographic separation of several metal chelates with 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulphopropylamino)phenol (5-Br-PAPS) on a C₁₈-bonded stationary phase using methanol-water mixtures as the mobile phase is reported. The Fe^III-Bi^III-, In^III-and Tl^III-5-Br-PAPS chelates were separated in about 20 min using a LiChrosorb RP-18 column (125 × 4 mm i.d.) with methanol-water (65 + 35) as the mobile phase containing 1 × 10^–4M 5-Br-PAPS, 0.06 M butylamine and 0.05 M chloracetate buffer (pH 3). Visible detection limits at 580 nm are established in the range 0.1–1.2 ng of metal, except for Tl^III, which cannot be determined owing to degradation of the chelate on the column.