Figure 5 Determination of the TTC:vanadium molar ratios by the mobile equilibrium method; m=1. pH 5.5, *c*_{V(IV)} = *c*_{V(V)} = 3×10^{−5} mol dm^{−3}, *c*_{ND} = 4.0×10^{−4} mol dm^{−3}, *λ* = 333 nm (1 and 2) or 630 nm (1′ and 2′). 1 and 1′ obtained with V^{IV}, and 2 and 2′ – with V^{V}. Straight line equations: 1) y = 1.22x + 4.87; 1′) y = 1.02x + 4.19; 2) y = 1.02x + 5.15; and 2′) y = 1.02x + 5.39