Related Experiment Video
Updated: Jun 28, 2026

Quantification of Metal Leaching in Immobilized Metal Affinity Chromatography
Published on: January 17, 2020
Effects of auxiliary complex-forming agents on the rate of metallochromic indicator colour change
1Laboratory of Analytical Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, Japan.
Abstract:
The rates of colour change reactions of metallochromic indicators such as XO, PAN, PAC and TAC at the equivalence point were measured in the chelatometric titration of copper, nickel, zinc or cobalt. Hexamine buffer has strong disturbing effects on the rate of colour change of the copper or nickel XO chelate. The effects of various auxiliary complex-forming agents were also examined. Bathophenanthroline, 2,2'-bipyridyl, 8-hydroxyquinoline, TPTZ, ethylenediamine, iminodiacetic acid, acetylacetone, 1,10-phenanthroline and glycine improve the colour change of the XO and PAN chelates of copper. Some titration methods for copper or nickel with XO or PAN as indicator are proposed.
More Related Videos
13:21Preparation, Purification, and Characterization of Lanthanide Complexes for Use as Contrast Agents for Magnetic Resonance Imaging
Published on: July 21, 2011
10:31Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores
Published on: December 6, 2015
Related Concept Videos
EDTA: Auxiliary Complexing Reagents
Complexometric Titration: Overview
Effects of EDTA on End-Point Detection Methods
In the visual method, metal-ion indicators (metallochromic dyes), which have distinct colors in their free and complex forms, are added to the mixture to signal the titration's end point. They form stable complexes with metal ions, but these complexes are weaker than the corresponding metal–EDTA complexes. As a result, EDTA...
Formation of Complex Ions
Complexometric Titration: Ligands
Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.