Determination of vitamin B12 as cobalt by use of a catalytic-spectrophotometric method

Abstract

A kinetic-spectrophotometric method is proposed for the determination of vitamin B₁₂ as cobalt in pharmaceutical preparations. After digestion of the sample with concentrated sulphuric acid, cobalt in the range 0.20–13.00 ng ml^–1 can be determined catalytically by addition of a methanolic solution of pyrogallol red and hydrogen peroxide. The results are compared with those for the determination of cobalt by flame and graphite furnace atomic absorption spectrometry.