Voltammetry in sheep's blood: Membrane-free amperometric measurement of O2 concentration

An amperometric method was applied for the electroanalytical measurement of oxygen content in sheep's blood. This method was based on a bare platinum microdisc electrode coupled with the use of chronoamperometry. A linear relationship between the chronoamperometric current and the oxygen concentration was observed in both saline solution and sheep's blood. The developed method was able to measure the oxygen percentage with an error of ca. 1.3% in sheep's blood. In addition, this article presents the first study on direct voltammetry in sheep's blood and a dissociative CE process was proposed to explain the electrochemical behaviour of oxygen reduction in blood on a platinum electrode in which the 'free' oxygen was first dissociated from oxyhaemoglobin prior to electron transfer with the magnitude of the observed current controlled by the diffusion of oxyhaemoglobin to the electrode where for sufficiently large electrodes (greater than ca. 1 mu m in radius) the dissociation proceeds to completion on the voltammetric timescale allowing quantitative measurements.

Automated summary

An amperometric method was used to measure oxygen content in sheep's blood, with a linear relationship observed between chronoamperometric current and oxygen concentration. Additionally, this study presents the first investigation of direct voltammetry in sheep's blood and proposes a dissociative CE process to explain the electrochemical behavior of oxygen reduction.