625 lc system pump

Polymer acetylation degree (F_A) was determined by the first derivative UV spectrophotometric method using a Specord 205 spectrophotometer (Analtykjena, Jena, Germany) [19 (link)]. Polymer Mw and polydispersity index (PDI) were determined by size exclusion-high-performance liquid chromatography (SEC-HPLC). Size exclusion chromatography was carried out in a Waters 625 LC System Pump with an Ultrahydrogel column (I.D.: 7.8 mm, L: 300 mm) thermostated at 35 °C and connected to a Waters refraction index detector (Waters, Corp., Milford, MA, USA). Samples were dissolved at 3 mg/mL in the eluent (0.2 M acetic acid/0.15 M ammonium acetate buffer (pH 4.5)). Dextran standard kit (WAT054392, Waters, Corp.) was used to produce a standard curve to determine the average Mw of the chitosan samples.

GPC-HPLC was performed with a Waters 625 LC System pump with an Ultrahydrogel column (Waters, i.d. = 7.8 mm, l = 300 mm) thermostated at 35 °C. A Waters 2414 differential refractometer was used in the detection (Waters, Madrid, Spain). Ammonium acetate/0.2 mol/L acetic acid buffer (pH 4.5, 0.15 mol/L) was used as eluent. The flow rate was 0.6 mL/min and 20 μL samples dissolved in the buffer were injected.