Sublimation as a method of matrix application for mass spectrometric imaging
- 749 Downloads
Common organic matrix-assisted laser desorption/ionization (MALDI) matrices, 2,5-dihydroxybenzoic acid, 3,5-dimethoxy-4-hydroxycinnamic acid, and α-cyano-4-hydroxycinnamic acid, were found to undergo sublimation without decomposition under conditions of reduced pressure and elevated temperature. This solid to vapor-phase transition was exploited to apply MALDI matrix onto tissue samples over a broad surface in a solvent-free application for mass spectrometric imaging. Sublimation of matrix produced an even layer of small crystals across the sample plate. The deposition was readily controlled with time, temperature, and pressure settings and was highly reproducible from one sample to the next. Mass spectrometric images acquired from phospholipid standards robotically spotted onto a MALDI plate yielded a more intense, even signal with fewer sodium adducts when matrix was applied by sublimation relative to samples where matrix was deposited by an electrospray technique. MALDI matrix could be readily applied to tissue sections on glass slides and stainless steel MALDI plate inserts as long as good thermal contact was made with the condenser of the sublimation device. Sections of mouse brain were coated with matrix applied by sublimation and were imaged using a Q-q-TOF mass spectrometer to yield mass spectral images of very high quality. Image quality is likely enhanced by several features of this technique including the microcrystalline morphology of the deposited matrix, increased purity of deposited matrix, and evenness of deposition. This inexpensive method was reproducible and eliminated the potential for spreading of analytes arising from solvent deposition during matrix application.
- 9.Lechene, C.; Hillion, F.; McMahon, G.; Benson, D.; Kleinfeld, A. M.; Kampf, J. P.; Distel, D.; Luyten, Y.; Bonventre, J.; Hentschel, D.; Park, K. M.; Ito, S.; Schwartz, M.; Benichou, G.; Slodzian, G. High-Resolution Quantitative Imaging of Mammalian and Bacterial Cells Using Stable Isotope Mass Spectrometry. J. Biol. 2006, 5, 20.1–20.30.CrossRefGoogle Scholar
- 12.Pavia, D. L.; Lampman, G. M.; Kriz, G. S., Jr. Introduction to Organic Laboratory Techniques: A Contemporary Approach 2nd ed.; Saunders College Publishing: New York, 1982.Google Scholar
- 13.French, J. The Art of Distillation or a Treatise of the Choicest Spagyrical Preparations, Experiments, and Curiosities, Performed by Way of Distillation. In Art of Distillation, Cotes for E. T. Williams: London, 1667; pp 1616–1657.Google Scholar
- 18.Paxinos, G.; Franklin, K. B. J. The Mouse Brain in Stereotaxic Coordinates, 2nd ed.; Academic Press: San Diego, CA, 2001.Google Scholar