Lipid peroxidation is a well-established mechanism of cellular injury in both plants and animals and is used as an indicator of oxidative stress in cells and tissues. Lipid peroxides, derived from PUFAs, are unstable and decompose to form a complex series of compounds, which include reactive carbonyl compounds, such as malondialdehyde (MDA). MDA can be quantified through a controlled reaction with thiobarbituric acid, generating 'Thiobarbituric Acid Reactive Substances' (TBARS). Cayman's TBARS (TCA Method) Assay Kit provides a simple, reproducible, and standardized tool for assaying lipid peroxidation in plasma, serum, urine, tissue homogenates, and cell lysates. The MDA-TBA adduct formed by the reaction of MDA and TBA under high temperature (90-100°C) and acidic conditions can be measured either colorimetrically at 530-540 nm or with much higher sensitivity fluorometrically at an excitation wavelength of 530 nm and an emission wavelength of 550 nm.