Rapid and sensitive colorimetric determination of cobalt(II)

Area of Science:

• Analytical Chemistry
• Spectrophotometry

Background:

• Accurate quantification of cobalt (II) is crucial in various matrices, including pharmaceutical formulations.
• Existing methods may suffer from interference by common co-existing ions and formulation components.

Purpose of the Study:

• To develop a highly selective and sensitive spectrophotometric method for determining cobalt (II).
• To validate the method's applicability in the presence of potential interfering substances found in geriatric and pharmaceutical formulations.

Main Methods:

• Spectrophotometric analysis utilizing 7-Nitroso-8-hydroxyquinoline-5-sulfonic acid sodium salt as a chromogenic reagent.
• Employing McIlvaine's pH 8 citric acid-phosphate buffer to enhance selectivity.
• Testing for interference from common metal ions (Fe, Cu, Zn, Mn, Ca, Mg), hormones, vitamins, and additives.

Main Results:

• The developed method demonstrated high selectivity and sensitivity for cobalt (II) determination.
• Interference from iron (II/III), copper (II), zinc (II), manganese (II), calcium (II), and magnesium (II) was effectively eliminated under the specified buffer conditions.
• The method showed no interference from common hormones, vitamins, and additives.
• A sensitivity of 0.37 µg of cobalt (II)/ml was achieved.

Conclusions:

• A robust and selective spectrophotometric method for cobalt (II) determination has been established.
• The method is suitable for analyzing cobalt (II) in complex matrices like pharmaceutical and geriatric formulations.
• The high sensitivity and minimal interference make this a valuable analytical tool.