Elimination of matrix-based interferences to a fluorescent nitrite/nitrate assay by a simple filtration procedure

Pathophysiological levels of oxygen radical metabolites have been studied as indicators of trauma caused by burn insult. The 2,3-diaminonaphthalene assay is routinely used in the determination of nitrite/nitrate levels in biological fluids and cellular extracts as one indicator of nitric oxide activity. Several laboratories, including ours, have noted matrix-based interferences resulting in decreased assay sensitivity during nitrite/ nitrate analysis. We evaluated filtration using Millipore Ultrafree-MC 10,000 NMWL filters for the ability to eliminate matrix-based interferences from human serum and tissue culture medium, thereby restoring assay sensitivity. (C) 2000 Academic Press.