%0 Journal Article %1 Ottoy1996 %A Ottoy, M. H. %A Varum, K. M. %A Smidsrod, O. %C THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, OXON, ENGLAND OX5 1GB %D 1996 %I ELSEVIER SCI LTD %J Carbohydr. Polym. %K ;; [ISI:] block c-13-nmr; chitins chitosans; euphausia-superba; field n-acetylation; nmr-spectroscopy; samples; %N 1 %P 17 -- 24 %T Compositional heterogeneity of heterogeneously deacetylated chitosans %V 29 %X Commercial chitosans prepared by heterogeneous alkaline deacetylation with different F-A values were fractionated into acid-soluble and acid-insoluble fractions. The amount of acid-soluble fractions increased with increasing time of deacetylation. The acid-soluble fractions were characterized with respect to fraction of acetylated units (F-A), diad frequencies, intrinsic viscosities, molecular weights and molecular weight distributions. F-A values for the acid-insoluble fractions were obtained using CPMAS C-13 NMR spectroscopy. As a control, the F-A values for the acid-soluble fractions determined from CPMAS C-13 NMR spectroscopy were compared and found to be consistent with the F-A values from H-1 NMR spectroscopy. The diad frequencies indicated that the acetyl groups in the acid-soluble fractions of the commercially heterogeneously deacetylated chitosans were randomly distributed. Determination of eta, M(w) and M(w)/M(n) indicated negligible depolymerization of the acid-soluble fractions when deacetylation was performed under a nitrogen purge at 75 degrees C. Chemical characterization revealed compositional heterogeneity in the chitosans, with chitin-like acid-insoluble fractions with F-A values between 0.88 and 0.95, and acid-soluble fractions with F-A values from 0.20 to 0.52. Copyright (C) 1996 Elsevier Science Ltd

@article{Ottoy1996, __markedentry = {[phpts:6]}, abstract = {Commercial chitosans prepared by heterogeneous alkaline deacetylation with different F-A values were fractionated into acid-soluble and acid-insoluble fractions. The amount of acid-soluble fractions increased with increasing time of deacetylation. The acid-soluble fractions were characterized with respect to fraction of acetylated units (F-A), diad frequencies, intrinsic viscosities, molecular weights and molecular weight distributions. F-A values for the acid-insoluble fractions were obtained using CPMAS C-13 NMR spectroscopy. As a control, the F-A values for the acid-soluble fractions determined from CPMAS C-13 NMR spectroscopy were compared and found to be consistent with the F-A values from H-1 NMR spectroscopy. The diad frequencies indicated that the acetyl groups in the acid-soluble fractions of the commercially heterogeneously deacetylated chitosans were randomly distributed. Determination of [eta], M(w) and M(w)/M(n) indicated negligible depolymerization of the acid-soluble fractions when deacetylation was performed under a nitrogen purge at 75 degrees C. Chemical characterization revealed compositional heterogeneity in the chitosans, with chitin-like acid-insoluble fractions with F-A values between 0.88 and 0.95, and acid-soluble fractions with F-A values from 0.20 to 0.52. Copyright (C) 1996 Elsevier Science Ltd}, added-at = {2011-11-04T13:47:04.000+0100}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, OXON, ENGLAND OX5 1GB}, author = {Ottoy, M. H. and Varum, K. M. and Smidsrod, O.}, biburl = {https://www.bibsonomy.org/bibtex/26d61bcbdb788dcdbfd463513e7c1b673/pawelsikorski}, citedref = {AIBA S, 1991, INT J BIOL MACROMOL, V13, P40 ; ANTHONSEN MW, 1993, CARBOHYD POLYM, V22, P193 ; ANTHONSEN MW, 1994, CARBOHYD POLYM, V25, P13 ; ARAKI Y, 1975, EUR J BIOCHEM, V55, P71 ; CHRISTENSEN BE, 1996, IN PRESS CARBOHYDR P ; DAVIS B, 1984, CHITIN CHITOSAN RELA, P161 ; DOMARD A, 1987, INT J BIOL MACROMOL, V9, P333 ; DOMSZY JG, 1985, MAKROMOL CHEM, V186, P1671 ; DRAGET KI, 1992, BIOMATERIALS, V13, P635 ; FOCHER B, 1992, CARBOHYD POLYM, V17, P97 ; FOCHER B, 1992, CARBOHYD POLYM, V18, P43 ; HASEGAWA M, 1994, CARBOHYD RES, V262, P161 ; HIRANO S, 1988, CHITIN CHITOSAN, P37 ; KORYCKADAHL MB, 1978, CRC CRIT REV FOOD SC, V10, P209 ; KURITA K, 1977, MAKROMOL CHEM, V178, P3197 ; NIOLA F, 1993, CARBOHYD RES, V238, P1 ; NUDGA LA, 1971, ZH OBSHCH KHIM+, V41, P2555 ; OTTOY MH, 1996, IN PRESS CARBOHYDR P ; PAINTER TJ, 1968, ACTA CHEM SCAND, V22, P1637 ; PELLETIER A, 1990, BIOTECHNOL BIOENG, V36, P310 ; RAYMOND L, 1992, CARBOHYD RES, V246, P331 ; ROBERTS GAF, 1992, CHITIN CHEM ; SAITO H, 1982, CHITIN CHITOSAN, P71 ; SANDFORD PA, 1988, CHITIN CHITOSAN SOUR, P51 ; SANNAN T, 1976, MAKROMOL CHEM, V177, P3589 ; SASHIWA H, 1991, CARBOHYD POLYM, V16, P291 ; SASHIWA H, 1993, CARBOHYD RES, V242, P167 ; TANFORD C, 1961, PHYSICAL CHEM MACROM ; TANNER SF, 1990, MACROMOLECULES, V23, P3576 ; TERBOJEVICH M, 1992, CARBOHYD POLYM, V18, P35 ; VARUM KM, 1991, CARBOHYD RES, V211, P17 ; VARUM KM, 1991, CARBOHYD RES, V217, P19 ; VARUM KM, 1992, ADV CHITIN CHITOSAN, P127 ; VARUM KM, 1994, CARBOHYD POLYM, V25, P65}, interhash = {e24a84699522138c5b46a7221e64c5f2}, intrahash = {6d61bcbdb788dcdbfd463513e7c1b673}, isifile-dt = {Article}, isifile-ga = {UV490}, isifile-j9 = {CARBOHYD POLYM}, isifile-nr = {34}, isifile-pi = {OXFORD}, isifile-rp = {Ottoy, MH, NORWEGIAN INST TECHNOL,NORWEGIAN BIOPOLYMER LAB,DEPT ; TECHNOL,N-7034 TRONDHEIM,NORWAY.}, isifile-sc = {Chemistry, Applied; Chemistry, Organic; Polymer Science}, isifile-tc = {35}, issn = {0144-8617}, journal = {Carbohydr. Polym.}, keywords = {;; [ISI:] block c-13-nmr; chitins chitosans; euphausia-superba; field n-acetylation; nmr-spectroscopy; samples;}, language = {English}, month = JAN, number = 1, owner = {phpts}, pages = {17 -- 24}, publisher = {ELSEVIER SCI LTD}, size = {8 p.}, sourceid = {ISI:A1996UV49000004}, timestamp = {2011-11-04T13:47:21.000+0100}, title = {Compositional heterogeneity of heterogeneously deacetylated chitosans}, volume = 29, year = 1996 }