Irrespective of the sequence, the carbohydrate scaffold 1 as a molecular platform for combinatorial diversification can be selectively deprotected and equipped with side chains, for example amino acids or peptides, in every position (see picture). This allows the flexible arrangement of functional groups and structural elements. PG=protective group.
A sustainable and environmentally friendly procedure has been developed for the FTIR determination of caffeine in tea leaf samples. The method is based on the extraction with ammonia and CHCl3 and direct determination of caffeine on the chloroform extracts using peak height absorbance measurements at 1658.5 cm(-1) and external calibration. The method provides a sensitivity of 0.2142 absorbance units mg(-1) mL and a limit of detection of 1 mg L(-1), corresponding to 0.002% m/m caffeine in tea leaves. As compared with a reference procedure, based on UV absorbance measurement at 276 nm after low pressure column chromatography, the developed procedure reduces the consume of CHCl3 by a factor of 10, that of NH4OH by a factor of 20 and avoids the use of diethyl ether and Celite. The time required to do the analysis of a sample is 15 minutes as compared with the 6 hours for the reference one.
Von der Reihenfolge unabhängig kann das Kohlenhydratgerüst 1 als molekulare Plattform für eine kombinatorische Differenzierung an jeder Position selektiv deblockiert und mit Seitenketten, z. B. Aminosäuren (Peptiden), ausgerüstet werden (siehe Bild). Dies ermöglicht die flexible Anordnung von Funktionen und Strukturelementen. PG=Schutzgruppe.
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