Laser desorption combined with SPME for GC-MS analyses

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We highlight today an article that describes the combination of laser desorption and solid phase microextraction (SPME) for the analysis of solid samples. The article has been published in Rapid Communications in Mass Spectrometry under the title "Laser desorption sample transfer for gas chromatography/mass spectrometry" (1). It is not necessary to describe the potential of SPME since it is a well established technique in almost every analytical laboratory. Despite its potential, SPME is the focus of an intense research and its direct combination with mass spectrometry (MS) or its in-vivo applications are strongly remarkable.

Our colleagues, from the Louisiana State University, have proposed an innovative approach that allows the isolation of target compounds from solid samples followed by their preconcentration in a conventional SPME fiber. The manifold proposed is quite simple. First of all, the sample (solid or liquid) is deposited in a metal target. A laser radiation is focused on the surface of the sample spot inducing the desorption of the target compounds (and other matrix components). As the laser is applied in a defined angle, the desorption takes place in reflection geometry and the desorbed analytes are aspirated by a vacuum pump through a transference line (heated to avoid condensation) to the SPME extraction holder. In this holder, the analytes are finally retained in a conventional fiber which will be further analyzed by GC-MS.


The proposed configuration has been evaluated, under a proof-of-concept format, using caffeine, ibuprofen and several nitro-aromatic compounds as model analytes. We recommend the reading of the article, where you can find the complete description of the interface (including all the experimental variables) and the explanation of the different applications (including the analysis of cigarette smoke previously retained in a membrane).

Reference:
(1) Laser desorption sample transfer for gas chromatography/mass spectrometry. Link to the article

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