Speciation in the chromium(III)-glutathione system

The hydrolysis of chromium (III) cation and the complex species formed between chromium(III) and glutathione (H3L) in aqueous solution (25degreesC and 0.15 M in KCl ionic medium) have been studied potentiometrically. The application of the least-squares computer LETAGROP including the LETAGROP-FONDO version, indicates that under the employed experimental conditions (glutathione-chomium (III) ratios of 5.2 less than or equal to R less than or equal to 12.6; concentrations in the range 0.0052 less than or equal to M less than or equal to 0.007 and 0.027 less than or equal to L less than or equal to 0.084 mol dm(-3); pH range 2.0 less than or equal to pH less than or equal to 7.09); the hydrolytic species [Cr(OH)](2+), [Cr(OH)(2)](+) and [Cr-2(OH)(2)](4+) and the complex species [Cr(H2L)](2+), [Cr(HL)](+), [CrL], [Cr(OH)L)] and [CrL2](3-) (in the chromium-glutathione system) were found in significant amounts. The stability constants of the species formed were determined. The values are confirmed by HYPERQUAD program. The results are discussed.