Here we present SEC-MALLS study for chitosan samples with weight average molar mass M_w between 33 and 427 kg/mol on columns packed with 8 μm porous particles. A low injection concentration on the order of 0.1~0.2 mg/mL must be used to avoid overloading of the SEC columns, due to the extended coil conformation of cationic chitosan in the dilute acid buffer as compared to neutral polymers. Additionally, SEC must be performed at an eluent flow rate no more than 0.5 mL/min for high molar mass chitosan samples. At flow rates of 1.0 and 1.5 mL/min, the elution of the largest chitosan species is delayed, which leads to a distortion of the molar mass distribution towards lower molar mass region. Such an abnormal behavior is due to a chromatographic mode transition from SEC to slalom chromatography, originated from the coil―stretch transition of chitosan chains in elongational flow through the packed columns.

在这里，我们对重均摩尔质量为M _w的壳聚糖样品进行SEC-MALLS研究填充8μm多孔颗粒的色谱柱上的重量介于33和427 kg / mol之间。与中性聚合物相比，由于稀酸缓冲液中阳离子壳聚糖的盘绕构象延长，因此必须使用0.1〜0.2 mg / mL左右的低进样浓度来避免SEC色谱柱超载。此外，对于高摩尔质量的壳聚糖样品，SEC必须以不超过0.5 mL / min的洗脱液流速进行。在1.0和1.5 mL / min的流速下，最大的壳聚糖物质的洗脱被延迟，这导致摩尔质量分布向较低摩尔质量区域的变形。这种异常行为是由于从SEC到平流色谱的色谱模式转换所致，这是由于壳聚糖链在通过填充柱的伸长流中的盘绕-拉伸转变所致。