Picomole quantitation of ammonia by flow-through fluorometry.

A new fiber optic fluorometer has been used to measure picomole amounts of ammonia. The method is based on the enzymatic conversion of alpha-ketoglutaric acid and ammonium ion to glutamate with associated oxidation of NADH. The decrease in NADH fluorescence is used to quantify sample ammonia content. The method is rapid and reproducible and is capable of resolving differences as small as 0.3 pmol between samples containing 0-7 pmol.