Measurement of circulating nitrite and S-nitrosothiols by reductive chemiluminescence

Considerable disparities in the reported levels of basal human nitrite and S-nitrosothiols (RSNO) in blood have brought methods of quantifying these nitric oxide (NO) metabolites to the forefront of NO biology. Ozone-based chemiluminescence is commonly used and is a robust method for measuring these species when combined with proper reductive chemistry. The goal of this article is to review existing methodologies for the measurement of nitrite and RSNO by reductive chemiluminescence. Specifically, we discuss in detail the measurement of nitrite and RSNO in biological matrices using tri-iodide and copper(I)/cysteine-based reduction methods coupled to chemiluminescence. The underlying reaction mechanisms, as well as the potential pitfalls of each method are discussed.