Reactive oxygen species (ROS), aerobic organisms, are active products continuously produced in the process of their own metabolism due to the stimulation of internal and external environment. Under natural physiological conditions, the increase and decrease of oxidative molecules cannot be prevented, and the oxidation/antioxidant balance shifts to the oxidation state, which will lead to a variety of diseases related to oxidative stress. The concentrations of different oxidants in serum (or plasma) can be measured individually by experiment, but the process is time consuming, costly and technically complex. Since it is not practical to measure the different oxidant molecules individually and their oxidation effects are additive, the total oxidation state (TOS) of the sample determined is needed.
