On-line collection/concentration of trace metals for spectroscopic detection via use of small-sized thin solid phase (STSP) column resin reactors.: Application to speciation of Cr(III) and Cr(VI) Original Research Article

A novel and simple on-line flow injection (FI) system using anion- and cation-exchange resin disks was developed for the speciation of chromium species in fresh water samples by inductively coupled plasma-atomic (optical) emission spectrometry (ICP-AES). Two kinds of ion-exchange resin disks packed in line-filters were fixed and serially connected on the loop of each six-way valve. Five milliliters of a sample solution (pH 4.5) was introduced into the system. Anionic chromate ion, Cr(VI), was collected on the anion-exchange resin disk while cationic chromium ion, Cr(III), was collected on the cation-exchange resin disk. The collected species were then sequentially eluted by 2 M nitric acid and nebulized to the plasma of ICP-AES system. The detection limit (3σ) of Cr(VI) and Cr(III) were 0.04 and 0.02 μg l−1, respectively. The proposed method was applied to the speciation of Cr(III) and Cr(VI) in fresh water samples.