Molecular weight determination of 83% degree of decetylation chitosan with non‐Gaussian and wide range distribution by high‐performance size exclusion chromatography and capillary viscometry

Molecular weight determination of 83% degree of deacetylation (DD) chitosan with non‐Gaussian and broad molecular weight distribution by high‐performance size exclusion chromatography (HPSEC) and by capillary viscometry were proposed. The relationships between weight average retention volumes (RV w ) of HPSEC and intrinsic viscosities ([η]) measured by capillary viscometer and the weight average molecular weight ( Mw ) measured by static light scattering were established for routine molecular weight determination of chitosans either by HPSEC or by the capillary viscometry method, respectively. These results showed: relationships of RV w and Mw for different Mw of 83.0% DD chitosans can be expressed by the equation Log Mw = −0.433 RV w + 11.66. The RV w of other DD chitosans do not correlate well with this equation. It indicated that DD of chitosan affected the relationship of RV w and Mw of chitosans studied. The Mark–Houwink constant a decreased from 0.715 to 0.521, as the solution ionic strength increased from 0.01 M to 0.30 M, whereas constant k increased from 5.48 × 10 −4 to 2.04 × 10 −3 over the same range of ionic strength solutions. The established RV w and Mw equation and [η] and Mw equation (Mark–Houwink equation) can be routinely used to determine the molecular weight from RV w or [η] of chitosan by HPSEC or by capillary viscometer, respectively, without the need of expensive instrumentation. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1905–1913, 1999