Determination of V(V) by a kinetic stopped-flow FIA method with spectrophotometric detection

In the present paper, two automatised methods to determine V(V) in water samples are described. A continuous flow system based on the classical reaction for the determination of vanadium(V) with 3,3'dimethylnaphtidine in acid medium, by using a stopped-flow technique and spectrophotometric detection was developed (Method A). It was possible to increase the kinetic of the reaction obtaining a higher sample throughput (34 h(-1)), lower detection limits (0.2 mg l(-1)) and a high sensitivity. In order to determine still a lower concentration levels of V(V), a preconcentration step has been introduced in the above system (Method B). This manifold has a lower detection limits (0.032 mu g ml(-1)) and a high sensitivity (4 times greater than Method A). Both methods show a good reproducibility (RSD: Method A=1.9% and Method B=2.3%). (C) 1998 Elsevier Science B.V.