Many technologies currently exist that are capable of analyzing the surface of solid samples under ambient or vacuum conditions, but they are typically limited to smooth, planar surfaces. Those few that can be applied to non-planar surfaces, however, require manual sampling and a high degree of human intervention. Herein, we describe a new technique, Robotic Surface Analysis Mass Spectrometry (RoSA-MS), for direct surface sampling of three-dimensional (3D) objects. In RoSA-MS, a sampling probe is attached to a robotic arm that has 360° rotation through 6 individual joints. A 3D laser scanner, also attached to the robotic arm, generates a digital map of the sample surface that is used to direct the probe to specific (x, y, z) locations. The sampling probe consists of a spring-loaded needle that briefly contacts the object surface, collecting microscopic amounts of material. The probe is then directed at an open-port liquid sampling interface coupled to the electrospray ion source of a mass spectrometer. Analytes on the probe tip are dissolved by the solvent flow at the interface and mass analyzed with high mass resolution and accuracy. The surface of bulky, non-planar objects can thus be probed to give chemical maps with specific coordinates. Applications demonstrated herein include the examination of food surfaces, lifestyle chemistry, and chemical reactions on curved substrates. The modular design of this system also allows for simple modifications to the sampling probe and the ionization source, thereby expanding the potential of RoSA-MS for an even greater diversity of applications.

Robotic surface analysis mass spectrometry (RoSA-MS) of three-dimensional objects

255th National Meeting (2018)

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