Speciation in the chromium(III)-glutathione system

Abstract

The hydrolysis of chromium (III) cation and the complex species formed between chromium(III) and glutathione (H3L) in aqueous solution (25°C 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 ≤ R ≤ 12.6; concentrations in the range 0.0052 ≤ M ≤ 0.007 and 0.027 ≤ L ≤ 0.084 mol dm-3; pH range 2.0 ≤ pH ≤ 7.09); the hydrolytic species [Cr(OH)]2+[Cr(OH)2]+ and [Cr2(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. © 2004 2004 Taylor and Francis Group LLC.