For quantitative determination of nitric oxide (nitrate/nitrite) and evaluation of drug effects on its metabolism. Key Features: Sensitive and accurate. Detection range 0.6 - 200 µM in 96-well plate. Rapid and reliable. Using an optimized VCl₃ reagent, the time required for reduction of nitrate (NO₃^-) to nitrite (NO₂^-) is reduced to 10 min at 60°C. Simple and high-throughput. The procedure involves mixing sample with three reagents, incubation for 10 min at 60°C and reading the optical density. Can be readily automated to measure thousands of samples per day. Method: OD540nm. Samples: Plasma, serum, urine, tissue/cells and foods. Species: All. Procedure: Assay takes 40 min. Kit size: 100 tests. Detection limit: 0.6 µM.