Melamine, cyanuric acid, two compounds connected to tainted pet food, and related analogs have been analyzed using matrix-assisted laser desorption ionization/ time-of-flight mass spectrometry. (M þ H) þ ions were observed for ammelide and ammeline under positive ion conditions with sinapinic acid as the matrix. With alpha-cyano-4-hydroxy-cinnamic acid as the matrix, a matrix-melamine complex was observed; however, no complex was observed with sinapinic acid as the matrix. (M 2 H) 2 was observed for cyanuric acid with sinapinic acid as the matrix.