Chemiluminescence flow sensor for the determination of vitamin B 12

Abstract

A novel chemiluminescence (CL) sensor for vitamin B 12 combined with flow-injection analysis is presented in this paper. It is based on the catalytic effect of cobalt(II), liberated from vitamin B 12 by acidification, on the CL reaction between luminol, immobilized electrostatically on an anion-exchange column, and hydrogen peroxide electrochemically generated on-line via a negatively-biased electrode from dissolved oxygen in the flow cell. The sensor responds linearly to vitamin B 12 concentration in the 1.0 × 10 −3–10 mg l −1 range, and the detection limit is 3.5 × 10 −4 mg l −1 vitamin B 12. A complete analysis, including sampling and washing, could be performed in 1 min with a relative standard deviation of < 3.5%. The system is stable for over 500 determinations and has been applied successfully to the determination of vitamin B 12 in pharmaceutical preparations.