Nitro-Sulfuric acid is a kind of sulfur containing oxygen acid, the chemical formula is NOHSO4. It is used in chemical reactions to provide no+ ions. It can also be considered as a mixed anhydride of sulfuric acid and nitrous acid. NOHSO4 is used in organic chemistry to prepare heavy nitrogen salts from amines. A typical method is to dissolve sodium nitrite in an ice bath with concentrated sulfuric acid. Other reagents that can give the NO group include boric acid nitrite ([no]bf4) and nitrosamines chloride.