目的    应用液相色谱-质谱法（liquid chromatography-mass spectromety，LC/MS）和液相色谱-非数据依赖二级质谱数据采集技术（liquid chromatography-data independent acquisition mass spectromety，LC/MS^E）对利妥昔单抗及其类似药进行结构表征和相似性研究。方法    用LC/MS对利妥昔单抗及其类似药的完整蛋白及轻链和重链的相对分子质量进行测定；用基于LC/MSE的肽图分析确定利妥昔单抗及其类似药的氨基酸全序列；用LC/荧光检测法分析利妥昔单抗的糖基化修饰结构及相对含量。结果  LC/MS可准确测定利妥昔单抗的相对分子质量。基于LC/MS^E的肽图分析显示，利妥昔单抗的氨基酸序列覆盖率>99％。LC/荧光检测法对利妥昔单抗的糖谱分析具有较好的重复性。利妥昔单抗类似药与原研药的相对分子质量和糖型信息相符、氨基酸序列完全一致、糖谱相似。结论    LC/MS和LC/MS^E可用于利妥昔单抗及其类似药的结构表征和相似性比较，这为今后其他单克隆抗体结构表征平台的建立提供了依据。

Objective  To perform structural characterization and comparison study of Rituxmab and its biosimilar by liquid chromatography-mass spectromety (LC/MS) and liquid chromatography-data independent acquisition mass spectromety (LC/MS^E).  Methods   Relative molecular weights of intact and reduced monoclonal antibodies were determined by LC/MS. Amino acid sequences of Rituxmab and its biosimilar were identified using peptide mapping with LC/MS^E. Glycosylation profile of Rituxmab and its biosimilar were obtained through LC/Fluorescence detection (FLD).  Results   Relative molecular weights of intact and reduced Rituximab and its biosimilar were detected accurately by LC/MS. Peptide mapping with LC/MS^E showed that amino acid sequence coverage of Rituxmab was >99%. LC/FLD for glycosylation profile of Rituxmab had good repeatability. Rituximab and its biosimilar showed consistent relative molecular weights, identical amino acid sequences, and similar glycosylation profiles.  Conclusion    LC/MS and LC/MS^E can be used for structure characterization and comparison study of Rituxmab and its biosimilar, and provide basis for establishing structure characterization platform of other monoclonal antibodies in the future.