Robotic Surface Analysis Mass Spectrometry (RoSA-MS) of Three-Dimensional Objects

Abstract

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 nonplanar surfaces, however, require manual sampling and a high degree of human intervention. Herein, we describe a new platform, 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 a probe to specific ( x, y, z) locations. The sampling probe consists of a spring-loaded needle that briefly contacts the object surface, collecting trace 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. Material on the probe tip is dissolved by the solvent flow in the liquid interface and mass analyzed with high mass resolution and accuracy. The surface of bulky, nonplanar objects can thus be probed to produce chemical maps at the molecular level. Applications demonstrated herein include the examination of food sample surfaces, lifestyle chemistry, and chemical reactions on curved substrates. The modular design of this system also allows for modifications to the sampling probe and the ionization source, thereby expanding the potential of RoSA-MS for a great diversity of applications.

Automated 3D Sampling and Imaging of Uneven Sample Surfaces with LA-REIMS

“…This is faster than the surface sampling setups developed by Bennett et al and Li et al, which were on the order of minutes per measurement point. 4 , 6 The acquisition time for the 3D MS scanner is slower than the one reported by Ogrinc et al, which was approximately 0.6 s per measurement point with optimized parameters and simultaneous collection of topographical and MS imaging. 17 One of the reasons for the slower acquisition with the 3D MS scanner is the consecutive acquisition of the topographical scan and the MS measurement.…”

“…Samples prepared for 2D MSI techniques, such as matrix-assisted laser desorption/ionization (MALDI) and desorption electrospray ionization (DESI), are often sectioned to create planar surfaces for easy analysis. 3 − 6 Nevertheless, sectioning is not always an option for certain tissue types or surface analyses.…”

“… 4 In 2018, Li et al used a robotic arm with a needle probe combined with an open port sampling interface (OPSI) and showed the relative abundance of molecules on a plastic coffee cup cover, medicine blister pack, football, and six-well spot plate. 6 In 2021, Ogrinc et al coupled a robotic arm with the SpiderMass (a water-assisted laser desorption ionization MS technique) for in vivo surgical applications. 17 In this setup, 3D topographical imaging of the surface is combined with molecular surface sampling with the SpiderMass.…”

Vibrating tip spray ionization mass spectrometry for direct sample analysis

“…Overall, this method allowed direct analysis of various raw samples on various tips without the need for any hardware modification, showing new features and applications. In addition, the vibrating tip spray could be a highly potential technique by use of functionalized tips and robotic devices . Furthermore, it is possible to combine vibrating tip spray with LC to perform LC‐MS analysis under voltage‐free condition.…”

Robot-Assisted SpiderMass forin vivoReal-Time Topography Mass Spectrometry Imaging

“…Very few MS devices have been coupled to robotic or automated systems. For example, robotic surface analysis using a needle sampling probe attached to the robotic arm was previously described8 .Using a 3D laser scanner, Li et al created the 3D images of an object surface and analyzed single spots (0.2mm x 1.0mm x 0.6 mm) on the surface by MS using the robotic controlled injection in an open port sampling interface. The molecular (which was not certified by peer review) is the author/funder.…”