Chemistry

Jumping off the Page

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Science  22 Jan 2010:
Vol. 327, Issue 5964, pp. 394-395
DOI: 10.1126/science.327.5964.394-d
CREDIT: © SCIENCEPHOTOS/ALAMY

Few marriages of analytical methods have been as successful as that of chromatography and mass spectrometry; together they can tease out the chemical composition of extraordinarily complex mixtures. A typical apparatus incorporates a gas or liquid chromatograph, in which analytes travel through a separation column, and a downstream detector where their masses are measured. An early, no-frills variant of chromatography involved spotting samples on paper, an inexpensive and highly portable support medium. Wang et al. now show that this simple material can also be used as an ionization platform for introducing samples into mass spectrometers. Samples such as blood are spotted on the paper, which is then cut to a sharp triangular point. The paper is wet with a methanol-water solution, and a high positive bias (4.5 kV) is applied to the paper relative to the nearby inlet of a tandem mass spectrometry under ambient conditions; the precise mechanism for ion release remains somewhat unclear. The authors demonstrate the detection of drugs such as Gleevec in blood, as well as picogram quantities of cocaine swabbed from a surface. Chromatographic methods can also be used to separate components in a sample along the paper, which can then be cut into separate pieces for further analysis.

Angew. Chem. Int. Ed. 49, 10.1002/anie.200906314 (2010).

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