提出了一种用凝胶色谱与常规检测器检测褐藻胶分子量及其分布的方法。用高效凝胶渗透色谱(GPC)与示差检测器(RID)结合，建立了以普鲁兰标准品为对照的相对重均分子量、相对数均分子量与GPC–MALLS(多角度激光散射)测试的褐藻胶绝对重均分子量、绝对数均分子量间的转换关系，得到了用GPC–RID检测相对分子量计算褐藻胶绝对分子量和多分散系数的方法。结果表明，GPC–RID法经转换公式得到的重均分子量、数均分子量和多分散系数与GPC–MALLS法的相对误差在?12%以内。基于GPC–RID法可较准确地获得褐藻胶的绝对分子量及多分散系数，使用通用检测器可节约仪器投资，降低检测成本。

A method for the determination of molecular and molecular weight distribution of alginate by gel chromatography and conventional detector was proposed. Alginates in a wide range of viscosities extracted from two dominated raw materials—Lessonia nigrescence and Lessonia trabeculata were taken as the samples. The relative molecular weight of alginate was determined by high-performance gel permeation chromatography (GPC) combined with refractive index detector (RID) with pullulan served as a standard. The corresponding relations of relative weight average molecular weight ( ), relative number average molecular weight ( ) measured by GPC–RID and absolute weight average molecular weight ( ), absolute number average molecular weight ( ) measured by multi-angle laser scattering (GPC–MALLS) were obtained by least square method. The results showed that there was a good linear correlation between the relative molecular weight of alginate determined by GPC–RID and the absolute molecular weight of alginate determined by GPC–MALLS. The correlation index was more than 0.9. The relative error between the absolute weight average molecular weight determined by the established GPC–RID method and the absolute weight average molecular determined by GPC–MALLS was less than ?12%. The relative error between the absolute number average molecular weight determined by the established GPC–RID method and the absolute number average molecular determined by GPC–MALLS was less than ?12%. The polydispersity index calculated by the established GPC–RID method was less than ?12%, compared with that obtained by GPC–MALLS method. The GPC–RID method for the determination of the relative molecular weight of alginate can be used to determinate the absolute molecular weight and the polydispersity index of alginate. It manifested that it was feasible and economical to use the GPC–RID method provided in this work for the determination absolute of the absolute weight molecular weight, absolute number molecular weight and polydispersity index of alginate. The method can save the investment on the instrument and reduce the cost of determination the molecular weight of alginate.