Study of the binding equilibrium between Zn(II) and HSA by capillary electrophoresis–inductively coupled plasma optical emission spectrometry

A new method has been developed for following the interaction between zinc ion and human serum albumin (HSA) by capillary electrophoresis–inductively coupled plasma optical emission spectrometry. Under optimized experimental conditions, the detection limit (3σ) for free Zn2+ ion was found to be 1.34 μM by running 11 replicates of the reagent blank. The RSD was less than 3% and the recovery was more than 98.13%. The linear range of zinc ion concentration was between 5.1 μM and 0.3 M. The measured Zn(II)–HSA combination values of n1 and K1 for primary binding of Zn2+ to HSA were 1.09 and 2.29 × 105 L mol−1, respectively. The measured values of n2 and K2 for the non-specific binding of Zn2+ to HSA were 8.96 and 6.65 × 103 L mol−1, respectively. This new method allows rapid analysis of a small amount of sample, simple operation, while avoiding long periods of dialysis and eliminating interference from other metal ions. This method provides a reliable and convenient new way for studying interactions between metal ions and biomolecules.