Speciation of metals in solution by flow injection analysis. Part 1. Sequential spectrophotometric and atomic-absorption detectors

A general approach to the speciation of metals present in mixed oxidation states is described. It employs the use of sequential spectrophotometric and atomic-absorption detectors in a flow injection system.The application of this approach is illustrated by two examples. (1) The determination of chromium(VI) and total chromium in corrosion test sea water: this system can operate at up to 120 injections per hour with an injected sample volume of 30 µl. The working ranges are 1–50 p.p.m. of total chromium and 0.1–20 p.p.m. of chromium(VI). (2) The determination of iron(II) and total iron in mineral process solutions: this system can also operate at up to 120 injections per hour using either a 20-or a 100-µl sample. A 20-µl sample gave linear working ranges of 5–120 p.p.m. of total iron and 0.5–120 p.p.m. of iron(II), and a 100-µl sample gave working ranges of 0.5–25 p.p.m. of total iron and 0.2–25 p.p.m. of iron(II).Short-term repeatability and interference studies are discussed.