Hydrogen peroxide from the local shop (dilute, 2-3%) sometimes has a stabilizer to slow it's breakdown rate and increase it's "shelf-life", since we'd like to keep it around the house on our shelf for years, and the shop would like the option to keep on their shelf a while as well.
Examples of H2O2 stabilizers include acetanilide and sodium citrate.
This answer notes that the Soyuz spacecraft (the one with the now-patched hole) also has a "shelf-life" and this one is only about 200 days, for reasons explained there.
Is it known if the Soyuz spacecraft(s) docked to the ISS use chemical stabilizers in the peroxide (H2O2) so that it can remain docked at the ISS for 200+ days?
More info about the situation: