The reduction potential of the sample or standard effectively converts Cu+2 to Cu+1, thus changing the ion's absorption characteristics. This reduced form of copper will selectively form a stable 2:1 complex with the chromogenic reagent with an absorption maximum at ca. 450 nm12-16. A known concentration of Trolox is used to create a calibration curve, with the data being expressed as mM Trolox equivalents or in μM copper reducing equivalents. Sample Types: biological fluids. Range: 0.125 - 2.0 mM. Sensitivity: 0.125 ng/mL. Time: 3 minutes ? Oxidative stress has been implicated in a number of diseases such as atherosclerosis1, chronic inflammatory disease2, chronic renal failure3, and cancer4. It is a condition where an imbalance exists between the production of reactive oxidizing species and the body's ability to neutralize these intermediates, resulting in cellular damage. The body has designed several physiological responses to oxidative stress including counterbalances5 such as enzymes and variously functionalized molecules (see examples below) that effectively neutralize these damaging species. These antioxidants can be either water or lipid soluble, and are localized transiently throughout various tissues, cells and cell types.