organic nitrates
From Glossary of Meteorology
Nitrogen-containing compounds, general formula RONO2, where R is an alkyl (or organic) group; formed in a minor (2%–30%) channel of the reaction of nitric oxide with the corresponding alkylperoxy radical.
The extent of formation of organic nitrates in an air mass has been used as a measure of the age of the air mass. They are a reservoir species for [[NOx]].