Post-Synthetic Analysis

Like peptide oligomers, peptoids can be analyzed by HPLC and by mass spectrometry. They can be sequenced by Fdman degradation [13] or by tandem mass spectrometry [14] since, like polypeptides, they conveniently fragment along the main chain amides [15, 16]. 

Drug Discovery via Smaii-Moiecuie Peptoid Libraries 

Because of their ease of synthesis and their structural similarity to peptides, many laboratories have used peptoids as the basis for combinatorial drug discovery. Peptoids were among the first non-natural compounds used to establish the basic principles and practical methods of combinatorial discovery [17]. Typically, diverse libraries of relatively short peptoids ( 10 residues) are synthesized by the mix-and-split method and then screened for biological activity. Individual active compounds can then be identified by iterative re-synthesis, sequencing of compounds on individual beads, or indirect deduction by the preparation of positional scanning libraries. 

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For most assays, where the compound is easily detected and there are relatively high concentrations in a simple matrix, then isocratic elution is usually preferred, since it is simple and no post-equilibration phase is required prior to the next analysis. However, with degradation products, excipients or synthetic intermediates, products of side reactions of differing lipophilicites are likely to be encountered, and then gradient elution may be used. 

Flow analysis has been used to investigate the fundamental chemistry of chemiluminescence and bioluminescence reactions, to optimise post-column chemiluminescence reaction conditions for liquid chromatographic detection and to quantify analytes in relatively simple or synthetic matrices [68]. In recent years, there has been a pronounced increase in the application of these methods to the analysis of real sample matrices [69]. This has usually been achieved by a combination of efficient in-line sample treatment, e.g., use of solid-phase reagents for concentrating selected analytes and/or for removing the sample matrix and exploitation of more inherently selective reactions [70,71],... 

Fig. 19.6 HPLC analysis of the female-produced sex pheromone isolated from female conditioned seawater (Hardege, unpublished data). The chromatogram shows the HPLC analysis of female C. maenas urine at 2-day post-moult (black line), and synthetic pheromone, UDP (red line). HPLC conditions used were Phenomenex RP Fusion column (4.6 x 250 mm) mobile phase 0.2 M KH2PO4 buffer, pH 5.5 1 mL min-1. Synthetic pheromone UDP (for structure see insert) was at a concentration of 10-5 M. The unresolved shoulder peak in the female sample at 3.3 min represents both tautomeric forms of UDP...

Studies concerning the structural determination of some synthetic homopolymers by MALDI, combined with post-source decay or collisional-induced dissociation fragment ion analysis, show that the masses of individual end-groups can be determined from ion peaks generated by cleavage of the polymer backbone. ... 

Consequently, the post analysis was performed. AE waveforms at sensor locations were synthesized in an infinite space, taking into the source location and the moment tensor components. The reflection coefficient was taken into consideration to simulate the waveforms. The SiGMA procedure was applied to synthetic waveform set as the post analysis. Results are also given in Table 8.1. Because one event was located out of the specimen, results of 101 events are shown. Except this event, location errors between the SiGMA analysis and the post analysis were within 1 mm. But, the shear ratio changed drastically as found in Table 8.1. Following the post analysis, events of the shear ratio less than 10% different from those of the SiGMA analysis were selected as reliable solutions. 46 events were selected and are listed in Table 8.2. 

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