Voltammetric determination of cysteine at a carbon paste electrode modified with Cu(II)-salen complex

The electrochemical behavior of a modified carbon paste electrode (MCPE) with N,N′ ethylenbis(salicylideneiminato)copper(II) complex ([Cu(II)-Salen]) was investigated as a new sensor for cystein. The Britton-Robinson buffer with pH 5, 10% modifier in electrode, potential scanning rate of 20 mVs-1 and puls height of 50 mV were used as the optimum condition for the determination of cysteine using carbon paste electrode modified with Cu(II)-Salen complex. Under these optimum conditions, the resulting electrode demonstrated linear response with cysteine concentration in the range of 1-10 and 10-80 μM. The effects of potential interfering species were studied and it was found that only thiocyanate ion interfered in cysteine determination and the proposed procedure was free from most other interferences.