Ammonium acetate, also known as spirit of Mindererus in aqueous solution, is a chemical compound with the formula NH<sub>4</sub>CH<sub>3</sub>CO<sub>2</sub>. It is a white, hygroscopic solid and can be derived from the reaction of ammonia and acetic acid. It is available commercially.
The synonym Spirit of Mindererus is named after R. Minderer, a physician from Augsburg.
It is the main precursor to acetamide:
It is also used as a diuretic.
As the salt of a weak base (ammonium) and a weak acid (acetic acid), is often used to create a buffer solution. Ammonium acetate is volatile at low pressures. Because of this, it has been used to replace cell buffers that contain non-volatile salts in preparing samples for mass spectrometry. It is also popular as a buffer for mobile phases for HPLC with ELSD and CAD-based detection for this reason. Other volatile salts that have been used for this include ammonium formate.
When dissolving ammonium acetate in pure water, the resulting solution typically has a pH of 7, because the equal amounts of acetate and ammonium neutralize each other. However, ammonium acetate is a dual component buffer system, which buffers around pH 4.75 ñ 1 (acetate) and pH 9.25 ñ 1 (ammonium), but it has no significant buffer capacity at pH 7, contrary to common misconception.
Ammonium acetate is also used as a food additive as an acidity regulator; INS number 264. It is approved for usage in Australia and New Zealand.
Ammonium acetate is produced by the neutralization of acetic acid with ammonium carbonate or by saturating glacial acetic acid with ammonia. Obtaining crystalline ammonium acetate is difficult on account of its hygroscopic nature.