Analysis of Peptide- and Oligonucleotide-Libraries

In the following sections we present some examples of mass spectrometric analysis that are relevant to combinatorial synthesis. Unless otherwise mentioned, ESI is performed in combination with the quadrupole analyzer, whereas MALDI is used in combination with TOF-instrumentation. 

A special applicability of MALDI is the single bead analysis of peptides (— 1000 Da) with a TOF-analyzer [25] also using different resin linkers [26]. Improved resolution of mass spectra was achieved with the development of reflectron devices and post source decay for a direct structural readout of single compounds [27]. For direct ionization and desorption in the MALDI source, photosensitive linkers were developed [28,29]. 

With respect to the limited time which can be invested in order to characterize a large library, the low-resolving analyzer techniques in most cases only provide rough, finger- 

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