This document describes a protocol for quantitative determination of nitrite (NO2-) a stable oxidative end-product of the antimicrobial effector molecule nitricoxide in cell culture medium(1, 2). The protocol is used to evaluate the capability of nanomaterials to induce nitric oxide production by macrophages. Nitric oxide secreted by macrophages has a half-life of seconds; it interacts with a number of different molecular targets, resulting in cytotoxicity. In the presence of oxygen and water, nitric oxide interacts with it self to generate other reactive nitrogen oxide intermediates and ultimately decomposes to form nitrite (NO 2) and nitrate (NO 3).
