Measurement of nitrite in blood samples using the ferricyanide-based hemoglobin oxidation assay.

Nitrite is currently recognized as a biomarker of the state of nitric oxide metabolism. Therefore, assessing nitrite levels in various organs and compartments is an important issue. As nitrite levels in most organs and tissues are low (in high nanomolar or low micromolar range) several new sensitive methods for quantifying nitrite in various biological samples have been developed. Chemiluminescence, combined with tri-iodide reducing solution, is currently considered the most sensitive method, allowing quantification in the low nanomolar range of nitrite concentrations. Here, we present an overview of chemiluminescence-based determination of nitrite in blood and blood compartments - red blood cells and plasma. We also explain how to preserve the original physiological nitrite concentration in nitrite-hostile environments, such as an excess of hemoglobin in blood.