Abstract: Voltammetric behavior studies on the interaction of Ln³⁺ ions with NAD⁺ andNAD-LDHcomplex were presented.The results showed that Ln³⁺ interacted with NAD⁺ bydividing the reduction wave of NAD⁺ at -0.94 Vinto two waves, which could be attributedto the binding of Ln³⁺ ions with the pyrophosphorous moiety of NAD⁺.The effect of Ln³⁺ions on NAD⁺ was progressively eliminated by adding EDTA.On mercury electrode NAD⁺formed a complex with LDHand was reduced at-1.16 V.The dissociation constant ofNAD-LDHwas determined.When NAD-LDHcomplex was formed, the addition of5μmol/L La³⁺, Ce³⁺, Pr³⁺, Eu³⁺, Gd³⁺, Dy³⁺, Yb³⁺, Lu³⁺ respectively increased the dis-sociation constant of NAD-LDHcomplex in the range of 40%-70%.These results could beused as an explanation for the inhibition of Ln³⁺ ions on LDHactivity.

Key words: Ln³⁺ ions, NAD⁺, NAD-LDH, Voltammetric behavior