Spectrophotometric determination of cobalt with cobaltone-I (p-nitrophenylhydrazone of diacetylmonoxime)

Summary Cobalt(II) in ammoniacal solution forms a pink, water soluble complex with Cobaltone-I (p-nitrophenylhydrazone of diacetylmonoxime) in the p_H range 11.7–11.9 with absorption peak at 520 nm. The system obeys Beer's Law in the concentration range 0.5–5 ppm of cobalt. Effect of different variables on the colored complex has been studied in detail and optimum conditions determined. Most of the common anions do not interfere with the reaction. The tolerance limits of the cations (other than cobalt) forming soluble amines have been determined. Alkali cyanide raises these limits considerably.Note. For the sake of convenience only, the reagent has been given the trivial name, Cobaltone-I and is referred to as such in the following pages