COMPLEX-FORMATION EQUILIBRIA OF SOME HEAVY-METALS WITH AMINO-ALCOHOLIC BIOLOGICAL BUFFERS

The formation of complex species between mercury(II), lead(II) and cad mium(II) and some beta-amino-alcohols which are frequently employed as a pH buffer in biological studies is evidenced and discussed. The lig ands considered are 2-amino-2-methyl-1-propanol, 2-amino-2-methyl-1,3- propanediol and tris(hydroxymethyl)-aminomethane and differ from each other as regards the number of hydroxyl groups. From a comparison of t he equilibrium data, while the coordination of lead(II) is to be only attributed to the amino group, the hydroxyl groups also seem to contri bute to the coordination of cadmium(II). Equilibrium data related to m ercury(II) systems could not be deduced from potentiometric measuremen ts, owing to the high strength of the complexes formed.