Hydrogen peroxide was used as an oxidant in Flow Injection Analysis (FIA). The formation of gaseous components during the analysis was suppressed by maintaining a concentration lower than 0.15% of hydrogen peroxide in 0.1 M NaOH. By this method Cr(III) was oxidised on-line to Cr(VI) which was detected spectrophotometrically at 548 nm by complexation with 1,5-diphenylcarbazide (DPC). Linear responses was found for concentrations less than 20 mg/L and the sensitivities obtained of the pure species were 0.0225 ± 0.0015 L/mg for Cr(III) and 0.0420 ± 0.0015 L/mg for Cr(VI). For the speciation of Cr(III) and Cr(VI) the analysis of both species was performed by treating them as mutual interference’s. Thus, the total amount of chromium species was measured by FIA and the total amount of chromium was measured by Graphite Atomic Absorption Spectrometry (G-AAS). The speciation was then performed at concentrations above 6 mg/L which is suitable for on-line monitoring of e.g. waste waters.
|Journal||Analytica Chimica Acta|
|Publication status||Published - 1998|