Glutathione helps protect cells from free radical damage by acting as an antioxidant. Within cells, glutathione exists in reduced (GSH) and oxidized (GSSG) states. In addition to its role in oxidative stress, glutathione also helps maintain exogenous antioxidants such as vitamins C and E. Glutathione is involved with the breakdown of peroxides. It has a role in regulating the nitric acid cycle. Cell Biolabs’ OxiSelect™ Total Glutathione Assay Kit is a quantitative assay for measuring the total concentration of glutathione, which encompasses both reduced and oxidized glutathione (GSH and GSSG) from plasma, blood, saliva, urine, tissue extracts, and plant or mammalian cell lysates. The kit employs a simple enzymatic recycling reaction for total glutathione quantification. The kit has a detection sensitivity limit of 8 nM. Each kit provides sufficient reagents to perform up to 100 assays, including standard curve and unknown samples.