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

Abstract

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(V1) 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 30yl. The working ranges are 1-50 p.p.m. of total chromium and 0.1-20 p.p.m. of chromium(V1). ( 2) The determination of iron(l1) and total iron in mineral process solutions: this system can also operate at up to 120 injections per hour using either a 20or a 100-yl sample. A 20-$ sample gave linear working ranges of 5-120 p.p.m. of total iron and 0.5-120 p.p.m. of iron(ll), and a 100-yl sample gave working ranges of 0.5-25 p.p.m. of total iron and 0.2-25 p.p.m. of iron(l1).

New method for simultaneous determination of Fe(II) and Fe(III) in water using flow injection technique

“…differential pulse anodic stripping voltammetry [12], amperometry and differential pulse polarography [13,14], ICP [15], AAS [16,17] as well as combination of spectrophotometry and AAS [18,19] were also reported.…”

Simultaneous speciation of chromium by spectrophotometry and multicomponent analysis

“…One of the most used colorimetric methods for the Cr(VI) andyor total chromium determination is based on the reaction of Cr(VI) with diphenylcarbazide (DPC) (Lynch et al, 1984;Andrade et al, 1985;Milacic et al, 1992;Sule et al, 1996;Clesceri et al, 2002;Mulaudzi et al, 2002;Giusti et al, 2005). The absorbance of the red -violet complex of unknown composition, formed at the pH range of 1.6 -2.2, is read at 540 nm (Clesceri et al, 2002).…”

Flow Injection System for Simultaneous Determination of Iron(III) and Iron(II) with a Single Detector and a Single Injection

“…It was also found that the relative error for iron(III) tends to become larger than that for iron(II). This may result from an estimation of the iron(III) concentration by difference, as observed by Lynch et al 8 The method for iron speciation described here, however, is simple and rapid, requiring no complicated separation process. This approach has the advantage of achieving a better signal resolution as well as an easy and reliable measurement of the signal height in comparison with a system using a large volume sample injection reported earlier.…”