Determination of complex formation constants for Cu(II)-Alizarin complexone with amines by capillary zone electrophoresis

Complex formation constants between Cu(II)-Alizarin complexone (Cu(II)-ALC) and amines were investigated by capillary zone electrophoresis. The electrophoretic mobility (mu(ep)) Of CU(II)-ALC was obtained from the migration time of 3 mu g ml(-1) Cu(II) in a berate buffer in the presence of 1 x 10(-3) mol dm(-3) ALC of pH 9.1 at 20 kV. The mu(ep) value decreased with increasing amine concentration as additive in the buffer. This indicates coordination of the amines with Cu(II)-ALC. The first and second coordination equilibrium constants (dm(3) mol(-1)) were 1 +/- I and(3.33 +/- 0.01) x 10(6), 100 +/- 1 and(4.73 +/- 0.01) x 106, 69 +/- 4 and (1.21 +/- 0.07) x 10(5), 2 +/- 1 and (2.74 +/- 0.06) x 10(5), 150 +/- 20 and 74 +/- 7, 5 +/- 1 and 74 +/- 3, 42 +/- 1 and 12 +/- 3, 57 +/- 1 and 9 +/- 2, (2.9 +/- 0.2) x 10(8) and 990 +/- 90, and 7900 +/- 200 and 780 +/- 70 for ammonia, methylamine, ethylamine, n-propylamine, pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, imidazole, and 1-methylimidazole, respectively. (C) 1999 Elsevier Science B.V. All rights reserved.