A new ambient ionization technique could turn mass spectrometry (MS) into a surgical tool by enabling the collection of mass spectra during surgery. Such a capability would be particularly advantageous for distinguishing cancerous from healthy tissue.
Zoltán Takáts of Justus Liebig University, in Giessen, Germany, and coworkers use a technique called rapid evaporative ionization MS to collect in vivo, in situ mass spectra from living tissue (Angew. Chem. Int. Ed., DOI: 10.1002/anie.200902546). The in situ measurement is "the first for any ambient ionization MS method and a major goal for all the methods," says R. Graham Cooks, a chemistry professor at Purdue University.
In the new method, electric current from an electrosurgical electrode heats and evaporates tissue, which is transferred to a mass spectrometer. Each measurement takes only a fraction of a second, so the method provides near-real-time analysis of the tissue while it is being cut.
Different tissues yield different mass spectra, and the researchers developed a tissue identification system using a spectral library and principal component analysis. When they tested the system in a canine melanoma model, they could distinguish the original melanoma and cancer cells that had traveled to the lymph node from healthy epithelial tissue.
The work is "very interesting," says Renato Zenobi, a professor at the Swiss Federal Institute of Technology, in Zurich, "especially because of the potential coupling to a surgeon's electrical or laser knife."