5- (2-HYDROXYBENZYLIDENE) -2,4-TIAZOLIDINDION AS ANALYTICAL REAGENT FOR EXTRACTION-PHOTOMETRIC DETERMINATION OF COBALT (II)

The possibility of using 5- (2-hydroxybenzylidene) -2,4-thiazolidinedione (L) for photo­met­ric determination of cobalt (II) has been studied. The best extractants were dichloroethane, chlo­roform and carbon tetrachloride. With a single extraction with chloroform, 97.6% of cobalt is reco­ve­red as a complex. The cobalt (II) complex is extracted into chloroform in the pH range 4.0-5.3. The maximum analytical signal for the complexation of cobalt with L is observed at 530 nm. The mo­lar absorption coefficient is 3.28 × 104. The ratio of components in the complex is Co: L = 1: 2. The extract of the cobalt complex obeys the basic law of light absorption at a concentration of 0.25-16 μg / ml. Based on the results of spectrophotometric studies of cobalt(II) with L, methods for determining cobalt in different objects have been developed. Keywords: cobalt, 5- (2-hydroxybenzylidene) -2,4-thiazolidinedione, extraction-photo­metric method