Interaction of dioxouranium(VI) ion with serine at different ionic strengths

The formation of complex species of dioxouranium(VI) ion with serine was studied in the pH range of 1-3.5 at 25 °C using a combination of potentiometric and spectrophotometric techniques. Results showed evidence for formation of the following species: UO2HL2+ and UO2(HL)22+. Investigations were performed in sodium perchlorate as background electrolyte at I (0.1, 0.3, 0.5, 0.7, and 1.0) mol dm− 3. The parameters based on the formation constants were calculated, and the dependences of protonation and the stability constants on ionic strength are described by a Debye-Hückel type equation. The dependence on ionic strength of the formation constants was also analyzed by the specific ion interaction theory (SIT) model. The stability constants at infinite dilution, obtained using this model, are logβ°111 = 1.32 ± 0.05 and logβ°122 = 2.74 ± 0.06, where indexes for the overall stability constant, βpqr, refer to the equilibrium pUO22+ + qH+ + rL− = (UO2)pHqLr(2p+q−r). The specific interaction coefficients are also reported.