title: High-resolution atmospheric pressure infrared laser desorption/ionization mass spectrometry imaging of biological tissue.
abstract: An atmospheric pressure laser desorption/ionization mass spectrometry imaging ion source has been developed that combines high spatial resolution and high mass resolution for the in situ analysis of biological tissue. The system is based on an infrared laser system working at 2.94 to 3.10 μm wavelength, employing a Nd:YAG laser-pumped optical parametrical oscillator. A Raman-shifted Nd:YAG laser system was also tested as an alternative irradiation source. A dedicated optical setup was used to focus the laser beam, coaxially with the ion optical axis and normal to the sample surface, to a spot size of 30 μm in diameter. No additional matrix was needed for laser desorption/ionization. A cooling stage was developed to reduce evaporation of physiological cell water. Ions were formed under atmospheric pressure and transferred by an extended heated capillary into the atmospheric pressure inlet of an orbital trapping mass spectrometer. Various phospholipid compounds were detected, identified, and imaged at a pixel resolution of up to 25 μm from mouse brain tissue sections. Mass accuracies of better than 2 ppm and a mass resolution of 30,000 at m/z = 400 were achieved for these measurements.
authors.affiliation: Institute of Inorganic and Analytical Chemistry, Justus Liebig University, 35392 Giessen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Römpp
authors.forename: Karl Christian
authors.initials: KC
authors.lastname: Schäfer
authors.forename: Sabine
authors.initials: S
authors.lastname: Guenther
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang
authors.forename: Martin
authors.initials: M
authors.lastname: Köstler
authors.forename: Arne
authors.initials: A
authors.lastname: Leisner
authors.forename: Carmen
authors.initials: C
authors.lastname: Paschke
authors.forename: Thorsten
authors.initials: T
authors.lastname: Schramm
authors.forename: Bernhard
authors.initials: B
authors.lastname: Spengler
mesh_terms: D000818:Animals; D001274:Atmospheric Pressure; D001923:Brain Chemistry; D003952:Diagnostic Imaging / Q000295:instrumentation; D004867:Equipment Design; D007259:Infrared Rays; D007834:Lasers; D013058:Mass Spectrometry / Q000295:instrumentation*; D051379:Mice; D010743:Phospholipids / Q000032:analysis*
chemical_list: D010743:Phospholipids