Rapid Quantification of Oxidized and Reduced Forms of Glutathione Using Ortho phthalaldehyde in Cultured Mammalian Cells In Vitro Determination of reduced glutathione by spectrophotometry coupled with anti interference compensation Analytical Methods (RSC Publishing) Frontiers GPI anchored glutathione S transferase as marker allows affinity sorting of transfection positive cells Assay for quantitative determination of glutathione and glutathione disulfide levels using enzymatic recycling method Nature Protocols