voltammetric determination of cysteine (2-amino-3- mercaptopropanoic acid, cysh) by means of 4,4′-biphenol as a homogeneous mediator

In the present research, 4,4′-biphenol was used as a homogeneous mediator for determining cysteine (cysh) on a glassy carbon electrode (gce). to describe the electrochemical properties of 4,4′-biphenol and to examine its electrocatalytic impacts on cysteine oxidation, both cyclic voltammetry (cv) and linear sweep voltammetry (lsv) were employed. our findings revealed that 4,4′-biphenol could significantly accelerate the reactions related to electron transfer to cysh. moreover, the diffusion coefficient of cysh and its reaction with the catalytic constant of 4,4′-diphenoquinone was estimated via chronoamperometry technique. the results showed that cysteine concentration range of 10-1000 μm led to linear increases in the oxidation peaks, thus to providing a detection of 0.99 μm with r² = 0.993. a relative standard deviation (rsd) of 2.5% was achieved after performing 7 cysteine replicates (100 μm), and cysh was successfully determined in real serum samples through the proposed approach.