Autofocusing MALDI mass spectrometry imaging of tissue sections and 3D chemical topography of nonflat surfaces.

We describe an atmospheric pressure matrix-assisted laser desorption-ionization mass spectrometry imaging system that uses long-distance laser triangulation on a micrometer scale to simultaneously obtain topographic and molecular information from 3D surfaces. We studied the topographic distribution of compounds on irregular 3D surfaces of plants and parasites, and we imaged nonplanar tissue sections with high lateral resolution, thereby eliminating height-related signal artifacts.