Peroxynitrate (or peroxonitrate) refers to

salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quant ...

s of the unstable peroxynitric acid, HNO₄. Peroxynitrate is unstable and decomposes to nitrate and dioxygen. No solid peroxynitrate salts are known. However, there is a report that the Russian chemist

Sebastian Moiseevich Tanatar Sevast’ian (or Sebastian) Moiseevich Tanatar (Севастьян Моисеевич Танатар) (Oct 7 (19) 1849, Odessa–Nov 30 (Dec 13) 1917) was a Russian chemist. He was born into a family of Karaite merchants in Odessa. When he w ...

produced sodium peroxynitrate octahydrate ( NaNO₃. H₂O₂.8H₂O) by evaporating a solution of

sodium nitrate Sodium nitrate is the chemical compound with the formula . This alkali metal nitrate salt is also known as Chile saltpeter (large deposits of which were historically mined in Chile) to distinguish it from ordinary saltpeter, potassium nitrate. ...

and

hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3 ...

until crystallisation begins and then mixing with alcohol to form crystals of the octahydrate.

References

Oxyanions {{inorganic-compound-stub