###### Abstract
The most common approach to measuring OS is to measure individual antioxidant levels in the same biological system, which tend to decrease in response to OS. Examples of this approach include those demonstrating a strong correlation between the decreased level of antioxidants and the severity of acute pancreatitis [17, 18] and intra-abdominal sepsis [19]. While this approach appears attractive, the reality is that there is a wide range of antioxidant compounds, and each of these requires a unique assay method for their measurement [16, 20, 21]. Furthermore, there is also a lack of consensus among researchers on how to measure and report antioxidant status across a broad spectrum of biological samples and diseases in a way that can yield meaningful and comparable results [22]. Cyclic voltammetry (CV) is a versatile electrochemical technique used to analyze redox status in a wide range of industrial and research settings. The common applications include evaluation of drug quality in pharmaceuticals [23, 24], determination of phenolics and antioxidants in food and wine [25], and label-free detection of biomolecules such as hormones [26, 27]. Conventional CV measurements are performed with a three-terminal cell configuration consisting of a working electrode (WE), a counter electrode (CE), and a reference electrode (RE) as shown in Figure 1. The technique measures the current response to a sweeping voltage potential applied to the sample via the WE. CV is highly sensitive to the detection of low-molecular-weight antioxidants (LMWA), which play a vital role in defence against OS [28]. Figure 2 shows a typical CV voltammogram of human plasma. The voltammetry peaks are due to the specific redox molecule(s) present in the biological sample, and the amplitude of current at each peak correlates with the concentration of the molecules [29, 30]. Traditional electrodes are reusable and can be made of different conductive materials and are formatted in a range of sizes and shapes. Studies have demonstrated CV can be used to assess the change of antioxidant level, disease severity and disease progression in rodent models of chronic and acute diseases, including acute pancreatitis and shock [31, 32, 33, 34]. Figure 1: (II) Conventional cyclic voltammetry setup with potentiostat connecting to three electrodes: working electrode (WE), the counter electrode (CE), and the reference electrode (RE). The electrode tips are submerged under the analyte in a sample vial. (I) A sweeping voltage potential is applied by the potentiostat to the analyte via WE; the potential increases and then decreases in the “cycle” at a pre-set duration. (III) The current response from analyte is measured at the WE and plotted against applied voltage potential in a voltammogram. The broad arrow indicates anodic current response, and the thin arrow indicates cathodic current response. While there have been some reviews on how to use CV to measure biological samples, they have been cursory [28; 29; 30; 35]. With the significant developments in the field of electrochemistry, this systematic review aims to examine all of the published studies to produce a detailed description and evaluation of CV methods for measuring antioxidant status in biological systems. As such, this paper will review the factors that are fundamental to the use of CV and will identify areas that require further validation and research.