Loading, determination peptide synthesis

Combustion (elemental) analysis of polymeric supports has mainly been used to determine the amount of halogens, nitrogen, or sulfur present in samples of cross-linked polystyrene (see, e.g., [54]). This information can be used to estimate the loading of a support, or, for example, to verify that the displacement of a halide has proceeded to completion. In solid-phase peptide synthesis, nitrogen determination has been used to estimate the loading of the first amino acid [55]. 

For solid-phase synthesis various linker molecules were constructed on the ULTRA resin 15. To determine the optimal spacer length, ULTRA resins were coupled with spacers of variable length. With 4-(4 -acetoxy-methyl-3 -methoxy-phenoxy) butyrate and a loading of 2.5 mmol/g the synthesis of heterocycles and peptides was investigated. A pyrazole carboxylic acid was prepared using a procedure established for Wang polystyrene... 

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