Potentiometric studies of Hg(II)-L-canavanine or/and L-arginine binary and ternary systems

The stability constants of binary and ternary complexes of mercury (II) with L-canavanine (Can) and its structural analogue, L-arginine (Arg) was determined by potentiometric measurements at 298 K and at ionic strength μ of NaNO 3 = 0.1 M in the pH range of 2 to 10. The data processing of every system studied by use of a 'pit mapping" method allowing determination of the distribution of every complex species as a function of pH. During binary complexation simple species like [Hg(Can)J, Hg(Can) 2 ], [HgArg] and [Hg(Arg) 2 ]}, together with hydroxylated species: [HgH - 1 ], [HgH - 1 Can] and [HgH - 1 Arg] were observed. Likewise, during ternary complexation, the existence of the dihydroxylated species [HgH - 2 CanArg] was observed with a large predominance over [HgCanArg].