The MaxSignal® Ammonia Assay Kit uses a coupled enzymatic reaction scheme to detect ammonia in food samples: ammonia in the sample is used as a substrate by the enzyme glutamate dehydrogenase to make glutamate. In the process, NADH is stoichiometrically converted to NAD+. This conversion, measured at 340 nm, is proportional to the level of ammonia in the sample. The absorbance of each sample at 340 nm is measured using a spectrophotometer. The concentration of ammonia in each sample is then directly determined from the change in NADH absorbance at 340 nm within 25 minutes. The assay offers both a cuvette-based format and a microtiter plate format for high-throughput sample analysis.