Coordination of mercury(II) to amino acids under physiological conditions

Abstract

The complex formation of mercury(II) with glycine(HL) and β-alanine(HL) was investigated under physiological conditions (at 37°C in 0.15 mol dm −3 NaCl aqueous solution) by glass-electrode potentiometry. From the analysis of the emf data in the two systems by use of computer program MIQUV, it was concluded that the species formed in both the systems are [HgL] + and [HgL 2] and their formation constants in the glycine system are larger than the corresponding ones in the β-alanine system, notwithstanding the lower basicities of the amino and carboxylate groups within glycine than those within β-alanine. The formation constants in the glycine system measured under the present experimental conditions (no data in the β-alanine system is available in the literature) are extremely less than those observed in different ionic media such as KNO 3, probably because chloride is bound to mercury(II) with high stability.