Abstract
Chromazurol S(H4L) in the presence of an excess of cobalt formed CoL2- with an absorption maximum at 595 mμ in the range of pH above 8.1 and CoHL- with an absorption maximum at 500 mμ in the range of pH below 6.4. They had the structures in which cobalt coordinated, respectively, to the phenolate-carboxylate and the carbonyl-carboxylate sites of Chromazurol S.
Cobalt in the presence of an excess of Chromazurol S formed a 1:2 complex with an absorption maximum at 567 mμ in the range of pH above 8.8 by which 0.082 ppm of cobalt was determined in 3.42×10-3M of Chromazurol S at pH 10. Its molar absorptivity was 3.3×104 and the sensitivity for 0.001 of the absorbance was 0.0018 μg/cm2.
