by Jeffrey M. Perkel Today’s mass spectrometers are faster, more
sophisticated and more sensitive than ever. Yet if the molecules
that are fed into these machines aren’t charged, the machine is
as blind as a bat. That’s because mass spectrometers don’t
actually measure a molecule’s mass, but rather its mass-to-
charge ratio (m/z). Given a molecule’s m/z value and its charge
state, researchers can compute the mass, but to do that the
molecule first must be vaporized and ionized. “If you don’t
ionize or you can’t ionize, then you can’t do mass
spectrometry,” says mass spec expert R. Graham Cooks, Professor
of Chemistry at Purdue University. Naturally, then, ionization
sources are critical components of any mass spec setup. So
critical, in fact, that two of the most popular life-science
ionization techniques, ESI (electrospray ionization) and MALDI
(matrix-assisted laser-desorption ionization), won their
inventors the Nobel Prize in Chemistry in 2002. ESI and MALDI
revolutionized biological mass spectrometry, and