Abstract
A novel, simple, sensitive spectrophotometric method is proposed for the determination of cobalt(II). Chloromine-T with iodine in acetic acid produces iodine monochloride, which oxidizes promethazine hydrochloride and diphenylamine to absorbing cations. Those would associate later with cobalt complex to form an ion pair, [Ph+] [CoCl4]-and [Dh2+] [CoCl4]-2in acid medium. These appear to provide exceptional color stability to the systems. The results compare favorably with those of reported method. The conditions required for the determination of cobalt(II) are described and related analytical parameters are also calculated.
Highlights
Cobalt is a naturally occurring element that appears in the first transition series of Group 9 (VIII) of the periodic table along with iron and nickel[1]
A biochemically important cobalt compound is vitamin B12.Vitamin B12 is a cofactor in critical biochemical reactions and is required for good health[3]
For the reagent sodium diphenylamine, aliquots of the standard Co(II) solutions containing 5 to[75] μg/mL were transferred into a series of 10 mL volumetric flasks
Summary
Cobalt is a naturally occurring element that appears in the first transition series of Group 9 (VIII) of the periodic table along with iron and nickel[1]. Silverstone and Bach[24] have described a spectrophtometric method for the determination of cobalt in nickel alloys by use of ethylenediaminetetraacetic acid and hydrogen peroxide at elevated temperature. Grahovac described the kinetic spectrophotometric[25] method for the determination of cobalt ion by the oxidation of Ponceau 4R by hydrogen peroxide. To each one of these flasks 0.75 mL iodine monochloride (0.009 M) followed by 1.5 mL of promethazine hydrochloride were added.
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