The GSSG/GSH Quantification kit contains Masking Reagent of GSH. The GSH can be deactivated in the sample by simply adding the Masking Reagent. Therefore, only the GSSG is detected by measuring the absorption (λmax = 412 nm) of DTNB (5,5’-dithiobis (2-nitrobenzoic acid) using the enzymatic recycling system. Also, GSH can be determined the quantity by subtracting GSSG from the total amount of glutathione.The kit is limited to quantifying GSH/GSSG concentration from 0.5 μmol/l to 50 μmol/l and GSSG concentration from 0.5 μmol/l to 25 μmol/l.