Determination of metal ion complexes in electroplating solutions using capillary zone electrophoresis with uv detection

Capillary zone electrophoresis with on-column UV detection at 214 nm was used to detect and determine iron cyanide complexes in liquid samples from zinc electroplating processes. Using a cathodic injection and anodic detection scheme, hexacyanoferrate(II) and -(III) ions were separated with separated with baseline resolution in under 5 min. A linear relationship between peak area and concentration was obtained for both ions, and the detection limit was lower than 10 μM. The experiments were extended to detect the presence of zinc hydroxo complexes in plating solutions. The electrophoretic mobility of this species was determined from the migration times, sampling simultaneously the zinc species at the cathode and adenosine, a neutral molecule that migrates with the electroosmotic flow, at the anode. The results seem to indicate the rpesence of the doubly charged species Zn(OH)2−4 in Zn11 solutions at pH > 10.5.