Preparation, characterization and spectrophotometric determination of cobalt ion via diazotization reaction and its application

Abstract

A spectrophotometric technique was developed utilizing Ethyl4-(5-acetyl-2,3,4-trihydroxyphenyl) diazenyl benzoate (EATDB) as a chromogenic agent for the identification of cobalt (II) ions at pH 9. Extensive investigations were conducted to assess the effects of pH, time, temperature, ionic strength, sequence of addition, and reagent concentrations on complex formation. The concentration range of cobalt (II) ions conforming to Beer's Law was determined as 1-100 μg.mL-1 under optimized conditions. The resulting complex exhibited maximum absorption at 437 nm with a molar absorptivity of 0.212x10³ L mol?¹ cm?¹. The limits of quantification and detection were established as 1.4 μg.mL-1 and 0.425 μg.mL-1, respectively. The stoichiometric ratio of the chelate [M:L] was determined to be 1:2 [Co-EATDB]. The developed method was successfully applied for the determination of Cobalt (II) complex ions in Vitamin B12.