Rapid Quantification of Oxidized and Reduced Forms of Glutathione Using Ortho phthalaldehyde in Cultured Mammalian Cells In Vitro Glutathione Assay (Colorimetric) A Derivatizing Agent for Glutathione Assays High Selectivity Fluorescence and Electrochemical Dual Mode Detection of Glutathione in the Serum of Parkinson's Disease Model Mice and Humans Analytical Chemistry Differentiating Changes in Glutathione Levels from Cytotoxic Events Using Multiplexed Assays Frontiers GPI anchored glutathione S transferase as marker allows affinity sorting of transfection positive cells