Direct detection of ultra-trace vanadium (V) in natural waters by flow-injection chemiluminescence with controlled-reagent-release technology

A new simple, rapid, selective and sensitive analytical procedure based on chemiluminescence (CL) detection is described for the determination of vanadium (V) at sub-nanogram levels in natural waters by use of controlled-reagent- release technology in a flow injection system. The analytical reagents involved in the CL reaction, including luminal and periodate, were both immobilized on anion-exchange resins in a flow injection system. Through water injection, luminol and periodate were eluted from the anion exchange column to generate the chemiluminescence, which was enhanced in the presence of V(V). The increased CL intensity was linear with V(V) concentration in the range from 0.2 to 100 ng mL− 1. The limit of detection was 60 pg mL− 1 (3σ) and the relative standard deviation (RSD) was 1.45% (n = 5) for a 0.5 ng mL− 1 V(V). At a flow rate of 2.0 mL min− 1, including sampling and washing, a typical analytical procedure could be performed in 0.5 min with a RSD of less than 3.0%. The proposed method was successfully applied to determine vanadium in natural waters, and the results were in good agreement with those obtained by ion chromatography.