SEC-RI-MALLS联用技术测定甲基纤维素的分子量及分子量分布

Establishment of determination method for the molecular weight and molecular weight distribution of methyl cellulose by SEC-RI-MALLS

目的:建立利用分子排阻色谱(SEC)与示差检测器(RI)和多角度激光光散射仪(MALLS)联用技术对甲基纤维素分子量及分子量分布进行测定的方法。方法:采用串接有TSKgelguard PWXL(6 mm×40mm)保护柱的TSKgel GMPWXL凝胶色谱柱(7.8 mm×300 mm,13μm),以0.1 mol·L-1硝酸钠溶液为流动相,流速为0.5 mL·min-1,柱温及示差检测温度为34℃,对来自国内外3个厂家的10批甲基纤维素样品进行了分子量及其分布的测定。结果:该方法测定各批次样品的重均分子量、数均分子量及分散度结果的误差均未超过5%,对同批次样品多次测定结果的RSD均未超过1.0%。结论:该方法操作简便,准确度及重复性良好,适用于甲基纤维素的分子量及分子量分布的测定,为甲基纤维素的质量控制提供了依据。

Objective:To establish a method for the determination of molecular weight and molecular weight distribution of methyl cellulose by size-exclusion chromatography(SEC)-differential refractive index(RI)-multi-angle laser light scattering(MALLS).Methods:The molecular weights and molecular weight distributions of ten batches of methyl cellulose samples from three manufacturers were determined by using 0.1 mol·L-1 NaNO3 solution as mobile phase with flow rate of 0.5 mL·min-1.The chromatographic column consisted of TSKgelguard column PWXL(6 mm×40 mm)as pre-column and TSKgel GMPWXL column(7.8 mm×300 mm,13μm)as separation column.The column temperature and the temperature of RI detector were operated at 34℃.Results:The errors of the weight average molecular weight,the number average molecular weight and the dispersion degree of each batch were not more than 5%,and the RSD for the results of the same batches was not more than 1%.Conclusion:The method is simple and accurate with good reproducibility.It is suitable for the determination of molecular weight and molecular weight distribution of methyl cellulose,and provides a reference for the quality control of methyl cellulose.