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| PDMS (Plasma Desorption Mass Spectrometry) |
PDMS schematic diagram.
In contrast to conventional mass-spectrometric methods, PDMS makes it possible to bring large, fragile organic molecules, with masses up to about 35,000 Dalton (e.g., proteins) undamaged into the gas phase as ions and to perform mass-spectrometric analyses.
To enable this, the spontaneous-fission decay propeties of Cf-252 are utilized. The resulting fission fragments bombard the sample in high vacuum (10-3 to 10-4 Pascal), whereby individual molecules are set free (plasma-desorption). These desorbed and ionized molecules enter a high-voltage field (ca. 10 kV), where they are accelerated in the direction of a grounded grid. After passing through this grid, they then traverse a ca. 50-cm-long field-free path, at the end of which sits a detector. The measured time-of-flight of the molecule enables a precise determination of its mass.
PDMS is dependable and efficient, as well as having a great variety of uses, especially in bioanalytics. Together with the university clinic here in Marburg, we are engaged in structural determinations of proteins and serological analyses of various cytostatic agents in tumor patients. In nuclear chemisry, PDMS is being used for the assay of long-lived transuranium elements in re-processed uranium. PDMS is even being used for the investigation of photosynthetic chromophores and tooth surfaces!
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