Square-wave voltammetry of human blood serum

The study concerns on the analysis of human blood serum by using square-wave
voltammetry (SWV) as a working technique. By exploring the SWV as the primary
voltammetric technique, best results have been obtained with Edge Plane Pyrolytic Graphite
Electrode (EPPGE) in comparison with the other electrodes used (Glassy Carbon or Pt
electrodes). In the electrochemical cell, a volume of 100-1000 μL of serum without any
treatment has been added into 10 ml of phosphate buffer with pH=7.34. Despite the complexity
of the serum as a medium, by using the EPPGE as a working electrode, three well-defined peaks
increase proportionally. This indicates that there is adsorption of uric acid (UA), bilirubin (BLR)
and albumin (ALB) going on to the surface of the working electrode. In addition, the parabolic
dependence of the measured peak-currents of all three peaks as a function of the SW frequencies
have been observed. This phenomenon is known as “quasi-reversible maximum” and it is
typical for systems undergoing an electrochemical transformation of the working electrode
from an adsorbed state. The effect of some interferences of organic systems present in the
human serum have been also monitored.
The major advantage of the method is that it is fast, inexpensive, and it does not require
treatment of the sample, as it is sensitive to micromolar concentrations. The major disadvantage
of the explored methods is that it requires very frequent electrode cleaning due to the adsorption
of compounds present in the human serum.