Direct and derivative spectrophotometric determination of cobalt with 5-bromosalicylaldehydethiosemicarbazone

Department of Chemistry, Sri Krishnadevaraya University, Anantapur-515 003, India Manuscript received 16 June 1999, revised 11 February 2003, accepted 12 March 2003 A simple and sensitive spectrophotometric method is developed for the determination of cobalt in aqueous DMF medium. The metal ion forms a brown coloured complex with 5-bromosalicylaldehydethiosemicarbazone (5-BSAT) in acidic medium. The complex shows absorption maximum at 410 nm. Beer's law is obeyed in the range 0.29-5.89µg ml-1 of cobalt(ll). A method for the determination of cobalt by third derivative spectrophotometry is also proposed. The methods have been employed successfully for the determination of cobalt in steel samples.