Mass Spectrometric Imaging Using Laser Ablation and Solvent Capture by Aspiration (LASCA)

Abstract

Abstract. A novel interface for ambient, laser ablation-based mass spectrometric imaging (MSI) referred to as laser ablation and solvent capture by aspiration (LASCA) is presented and its performance demonstrated using selected, unaltered biological materials. LASCA employs a pulsed 2.94 μm laser beam for specimen ablation. Ablated materials in the laser plumes are collected on a hanging solvent droplet with electric field-enhanced trapping, followed by aspiration of droplets and remaining plume material in the form of a coarse aerosol into a collection capillary. The gas and liquid phases are subsequently separated in a 10 μL-volume separatory funnel, and the solution is analyzed with electrospray ionization in a high mass resolution Q-ToF mass spectrometer. The LASCA system separates the sampling and ionization steps in MSI and combines high efficiencies of laser plume sampling and of electrospray ionization (ESI) with high mass resolution MS. Up to 2000 different compounds are detected from a single ablation spot (pixel). Using the LASCA platform, rapid (6 s per pixel), high sensitivity, high mass-resolution ambient imaging of Bas-receivedb iological material is achieved routinely and reproducibly.

Infrared Laser Ablation Microsampling with a Reflective Objective

“…Single focusing elements are simple and provide a working distance of several centimeters but can only focus the laser to a spot size of approximately 100 μm. 34 , 38 , 46 − 48 A typical multiple-element microscope objective has a high numerical aperture but small working distance that can be used in transmission mode ablation but otherwise limits access to the sample. 49 − 51 A central hole can be cut through a high numerical aperture objective to allow the ablated material to pass through, 52 − 57 but viewing the ablation process is otherwise obscured.…”

Localization of Metabolites of Human Kidney Tissue with Infrared Laser-Based Selected Reaction Monitoring Mass Spectrometry Imaging and Silver-109 Nanoparticle-Based Surface Assisted Laser Desorption/Ionization Mass Spectrometry Imaging

“…Between pixels, the sample stage moved with a speed of 2 mm/s. The time delay between pixels, during which the stage was moving along a straight line (the horizontal direction in Figures –), was 4 s, and the time delay between lines was 5 s. Control and analysis software was described recently …”

Laser Desorption/Ablation Postionization Mass Spectrometry: Recent Progress in Bioanalytical Applications

“…In a subsequent experiment, loading the laser‐ablated species onto a capillary electrophoresis column led to time‐resolved ESI‐MS analysis of peptides and proteins mixtures with theoretical plate numbers of between 1000 and 3000 (Park & Murray, 2013). Further, a laser ablation and solvent capture by aspiration (LASCA) system has been developed, which aspirates the extraction droplets, collects and pumps the remained laser‐ablated species in the form of a coarse aerosol to ESI (Brauer, Beech, & Sunner, 2015). Metabolic imaging of biofilms and plant tissue samples with up to 2000 compounds detected from a single pixel was demonstrated using the LASCA platform equipped with a mid‐IR laser.…”