Description_x000D_ Application_x000D_ Ammonia concentration was measured in serum and urine using the Sigma Ammonia Assay Kit in a study assessing expression of renal ammonia transporters in response to chromic metabolic acidosis._x000D_ This kit is for the quantitative, enzymatic determination of ammonia in food and biological samples. Ammonia reacts with α-ketoglutaric acid (KGA) and reduced nicotinamide adenine dinucleotide phosphate (NADPH) in the presence of L-glutamate dehydrogenase (GlDH) to form L-glutamate and oxidized nicotinamide adenine dinucleotide phosphate (NADP+). The decrease in absorbance at 340 nm, due to the oxidation of NADPH, is proportional to the ammonia concentration. L-Glutamate dehydrogenase reacts specifically with ammonia. The Ammonia Assay Kit may be used to determine ammonia concentrations in the range of 0.2-15 μg/ml.