2-Naphthyl caprylate is a substrate that is employed in an assays for carboxylesterase and lipase and when hydrolyzed, produces 2-naphthol, a compound that can also be identified via fluorescence analysis. By combining it with a diazonium salt, the formation of the corresponding azo dye occurs. In particular, this substrate is used to detect the extracellular lipase of Pseudomonas fluorescens B52.