Abstract.
A concentration-jump chemical relaxation catalytic procedure by using stopped flow injection is described with detection by spectrophotometry. The photoreduction of the Fe(III)-bipyridyl complex to Fe(II)-bipyridyl is pre-equilibrated at dark for at least 12 h. This solution is afterwards delivered by a peristaltic pump and mixed up with a stream of Co2+ solution as a catalyst. The mixture is confluenced down-stream with a flow of Fe(III) solution from a second pump, the concentration of which is about 30% of the pre-equilibrated Fe(III)-bipyridyl solution and acts as the perturbation (concentration-jump). The chemical relaxation process was monitored under thermodynamically non-equilibrium state, and the characteristic parameter of the relaxation process, relaxation time τ, is derived. The calibration graph between 1/τ and cobalt concentration is linear within 0.1–2.5 µg mL−1. The detection limit (LOD) and precision (RSD) are 9 ng mL−1 and 1.6%, respectively, both have been improved as compared to 12 ng mL−1 and 3.6% with a former reported manually operated procedure. The present procedure has been applied to the determination of cobalt in a certified reference material and a soil sample.
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Received June 15, 2002; accepted October 28, 2002
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He, R., Jiang, H. & Wang, J. A Stopped Flow Injection – Chemical Relaxation – Catalytic Spectrophotometric Procedure for the Determination of Cobalt. Microchim. Acta 141, 93–97 (2003). https://doi.org/10.1007/s00604-002-0933-5
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DOI: https://doi.org/10.1007/s00604-002-0933-5