Arachidonoyl m-Nitroaniline (AmNA) is one of several nitroaniline fatty acid amides which can be used to measure fatty acid amide hydrolase (FAAH) activity.{8928} FAAH is a relatively unselective enzyme in that it accepts a variety of amide head groups other than the ethanolamine of its nominal endogenous substrate anandamide (arachidonyl ethanolamide; AEA). It also will hydrolyze fatty acid amides with fewer carbons and fewer double bonds than arachidonate (see also Decanoyl m-Nitroaniline; Item No. 90349). Exposure of AmNA to FAAH activity results in the release of the yellow colorimetric dye m-nitroaniline (? = 13,500 at 410 nm). This offers the potential for fast and convenient measurements of FAAH activity using a 96 well plate spectrophotometer.