Speciation in the oxovanadium(IV)/glutathione system

The complex species formed in aqueous solution (25 degreesC; 1.5 mol dm(-3) KCL and 0.15 mol dm(-3) KNO3 ionic media) between the VO2+ cation and glut athione (H3L) were studied potentiometrically and spectrophotometrically. T he application of the least-squares computer program LETAGROP to the experi mental emf and UV-Vis data, taking into account hydrolysis of the VO2+ ion, indicated that under the employed experimental conditions (glutathione:van adyl (IV) ratio 5-50:1, pH range 2-9) only the species in the ligand/metal ratio 2:1, [VO(H3L)(2)](2+), [VO(H2L)(2)], [VO(H2L)(HL)](-) and [VO(HL)(2)] (2-) are formed in significant amounts. The stability constants were determ ined. The species distribution diagrams as a function of pH and the electro nic spectra were briefly discussed. (C) 2001 Elsevier Science Ltd. All righ ts reserved.