1985 Volume 34 Issue 1 Pages 36-39
A new spectrophotometric method for the determination of cobalt(II) with 2, 2'-dipyridylketone-2-picolylimine(DPPI) in the presence of sodium L-ascorbate is proposed. DPPI is prepared by heating an equimolar mixture of 2, 2'-dipyridylketone and 2-aminomethylpyridine in methanol. DPPI reacts with cobalt(II) to form a water soluble complex which has an absorption maximum at 580 nm. The calibration curve obeys Beer's law over the concentration range from 0.05 to 2.5 μg/ml of cobalt(II). The apparent molar absorption coefficient of the complex is 4.42 × 104 dm3 mol-1 cm-1. The recommended procedure are as follows ; To a sample solution, 1 ml of 10 % sodium L-ascorbate and 5 ml of 10-2 M DPPI solution are added. pH is adjusted to 8.511.1 with ammonia buffer solution, and the solution are heated gently to boil. After cooling the solution to room temperature, it is made up to 50 ml with water. The absorbance is measured at 580 nm against reagent blank. DPPI solution is stable for 50 d in a refrigerator. It is considered that DPPI acts as a tridentate ligand for cobalt(II), from the results of the color reactions of cobalt(II) with DPPI and other Schiff bases similar to DPPI.
