1,5-diaminonaphthalene (DAN) has previously been reported as an effective matrix for matrix-assisted laser desorption ionization-mass spectrometry of phospholipids. In the current work, we investigate the use of DAN as a matrix for small metabolite analysis in negative ion mode. DAN was found to provide superior ionization to the compared matrices for MW < ~400 Da; however, 9-aminoacridine (9-AA) was found to be superior for a uridine diphosphate standard (MW 566 Da). DAN was also found to provide a more representative profile of a natural phospholipid mixture than 9-AA. Finally, DAN and 9-AA were applied for imaging of metabolites directly from corn leaf sections. Published 2014. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]