Original Article

The Determination of The Stability Constants of Mixed Li-gand Comlexes of Creatinine-L-Cysteine and Creatinine-L-Cysteine Hydrochloride With Co(Ii), Cd(Ii), Zn(Ii), Mn(Ii): Using Potentiometric Method

  • Serap KARADERİ
  • Dilek BILGiÇ ALKAYA
  • Ayşen KURT CÜCÜ

Received Date: 06.11.2012 Accepted Date: 07.03.2013 Turk J Pharm Sci 2014;11(1):33-44

In this study, a potentiometric titration technique has been used to determine stability constants for the various complexes of Zn(II), Co(II), Cd(II) and Mn(II) with creatinine and two amino acids. Stability constants of ternary systems have been evaluated by the method suggested by Irving-Rossotti at 25°C and 0.11M ionic strength (kept constant with NaC104 in aqueous solution. In addition, the conditional constants were calculated as a function of pH. The maximum values of the conditional formation constants were found to be in accordance with the mixed-ligand complex formation constants in a given pH region. In addition, the mole fractions of different species from mixed complexes were calculated by means of formation constants. The values of stability constants of mixed-ligand complexes at 25°C were calculated as follows: logK=3.20 for Zn(II)-L-cysteine-creatinine,logK1=4 .24 and logK2=3.58 for Co(II)-L-cysteinecreatinine2, logK=3.22 for Cd(II) - L-cysteine - creatinine, logK=3.65 for Mn(II) - L-cysteine - creatinine and logK=5.34 for Co(II)-BDHL-cysteine-creatinine, logK=5.30 for Cd(II)-BDHL-cysteine-creatinine, logK1=5.35 and logK2 =3.93 for Zn(II) - BDHL-cysteine - creatinine2, logK1=5.40 and logK2=3.49 for Mn(II) - BDHL-cysteine - creatinine2.

Keywords: Creatinine, L-cysteine, BDHL-cysteine, Zinc(II), Cobalt(II), Cadmium(II) and Manganez(II) complexes, Mixed complex, Stability constants