Graphical methods of determination of stability constants of metal complexes using spectrophotometric and ion-selective electrode measurement data: cobalt(II)-PAR complex

Electrochemical Sensor Laboratory, Department of Chemistry, University of Allahabad, Allahabad-211 002, India

E-mail: mcc46@rediffmail.com

Manuscript received 21 June 2001. revised 19 June 2002, accepted 13 August 2002

A new heterogeneous Co^II-ion selective electrode has been developed and its characteristics have been studied. Using the electrode the stability constant of the complexes formed by Co^II-ion with 4-(2-pyridylazo)resorcinol (PAR) has been determined (log β₂ = 19.75) involving a graphical method. Stability constant of 1 : 2 complexes, determined by the ion-selective electrode (log β₂ = 19.75) agrees well with the value (log β₂ = 19.6) determined by spectrophotometric method.