RESEARCH PROFILE - SIMS and MALDI: better together

摘要

MS imaging promises unprecedented opportunities to visualize the chemical makeup of a cell. The most commonly used ion extraction techniques for MS imaging experiments are MALDI and secondary ion MS (SIMS). However, each method has drawbacks that limit the ability to obtain a detailed chemical snapshot. That's why Anthony Carado, Nicholas Winograd, and colleagues at Pennsylvania State University and Applied Biosystems/MDS Analytical Technologies united the two techniques in a single mass spectrometer, which will offer expanded capabilities to probe the chemical compositions of complex samples. They report their results in a new AC paper (2008, DOI 10.1021/ac801712s). To generate a chemical image with MALDI or SIMS, researchers raster scan across the sample surface and acquire thousands of mass spectra at different locations. Regions with particular chemical compositions are identified and color-coded to produce an image. In MALDI, the sample is treated with a thin coating of matrix before desorption with an ionizing laser beam. In C_(60) SIMS, the sample (which does not require a matrix) is bombarded with a beam of C_(60) cluster primary ions, or buckyballs, that dislodge secondary ions for mass spectrometric detection.