1982 Volume 31 Issue 9 Pages 504-508
Beryllium (II) reacted with Chromazurol S (CAS, H4L) to produce two types of 1 : 2 complexes in the presence of zephiramine, one of which was in a form of mononuclear Be(HL)24- showing an absorption maximum at 612 nm and other was in binuclear Be2(OH)(HL)49-showing an absorption maximum at 525 nm. The formation equilibrium of these complexes in the range of pH 5 to 10 was examined by the spectrophotometric method. The binuclear complex was found to be produced from the hydrolysis of the mononuclear complex through the following equation;
Be(HL)24-+1/2 H2O
⇔1/2 Be2(OH)(HL)49-+1/2 H+
where zephiramine ion was not shown. The effect of anions such as chloride and sulfate ions on this equilibrium was observed. The apparent equilibrium constant decreased with the increase of the anion concentrations. The equilibrium constant was larger in the presence of sulfate ion than in chloride ion at the same concentration. In the practical spectrophotometric determination, however, these effects by such diverse ions could be successfully elimination by raising the pH to 10 so high as the above equilibrium was shifted rightward thoroughly.
