GLUTATHIONE

Glutathione is the tripeptide γ-glutamyl-cysteinyl-glycine, and its odd γ-link joins glutamate through its side chain rather than its backbone, which sets it apart from ordinary peptides. The cysteine's free thiol (–SH) is the working part: it donates electrons to neutralize oxidants and to power glutathione peroxidases. That's why the ratio of reduced to oxidized l glutathione is a standard readout of oxidative stress, and why the form in the vial sets the baseline for the whole experiment.

Here's how it goes wrong. In the presence of oxygen and moisture, two GSH molecules link through their sulfur atoms to form GSSG, and a partly oxidized powder can still look perfectly clean. GSSG isn't an impurity in the usual sense; it's glutathione after the reaction your study might be measuring. Titan Core's glutathione is made in the USA as reduced L-glutathione and tested at an independent lab by HPLC, which separates GSH from GSSG, so the starting ratio is measured rather than assumed. The report carries the same LOT number as your vial, and a single LOT covers repeated assays. It's for laboratory research only, not a supplement or cosmetic, and not for human or veterinary use.