Résumé :
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The properties of starch derivatives which may be used as plasma substitutes, are dependent upon the molecular structure. Seven acetyl starch (AS) samples were determined and compared with results from hydroxyethyl starch (HES) samples. The molar masses and their distributions were determined with the combination of size exclusion chromatography and light scattering. Slightly asymmetric distributions were determined with a polydispersity M-w/M-n congruent to 2.4 and weight-average molar masses of M-w = 250,000-300,000 g/mol for six AS samples and M-w/M-n congruent to 3.6 and a weight-average molar mass of 766,000 g/mol for one AS sample.The average degrees of substitution (DS) and the substitution pattern were determined by high resolution NMR spectroscopy. The AS samplea investigated had a DS of 0.42 to 0.81, comparable to HES, but the regioselective substitution pattern revealed differences. While for HES the position C-2 is preferred and the position C-3 has nearly no substituent, for AS both positions, C-2 and C-3, are substituted likewise.
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