Abstract The azithromycin is a semisynthetic derivative of erythromycin A, and commercially produced by a series of chemical reaction involved Beckmann rearrangement followed by reductive methylation. Several azithromycin related compounds (ARCs) have been identified as impurity in the commercial products and the processes. These ARCs probably generated from impure starting material; a mixture of different erythromycin. Literature search revealed that approximately 90 erythromycins had been isolated and characterized so far. In current study, we have identified many new ARCs, including previously reported by detailed LC-MS/MS studies. In this study, first, the structures of ARCs were assumed by probable chemical transformation method; erythromycin A to azithromycin A; and, second, assumed structures of ARCs were confirmed by HRMS within the acceptable ppm error limit (±5 ppm) followed by MS/MS fragmentation to identify the characteristic common ion fragments and by precursor ion scan. GRAPHICAL ABSTRACT

中文翻译：

---

商业制剂中活性药物成分及其杂质的 LC-MS/MS 曲线

摘要 阿奇霉素是红霉素A的半合成衍生物，通过贝克曼重排和还原性甲基化等一系列化学反应商业化生产。几种阿奇霉素相关化合物 (ARC) 已被鉴定为商业产品和工艺中的杂质。这些 ARC 可能由不纯的起始材料产生；不同红霉素的混合物。文献检索显示，迄今已分离和表征了大约 90 种红霉素。在当前的研究中，我们已经确定了许多新的 ARC，包括之前通过详细的 LC-MS/MS 研究报告的。在这项研究中，首先，ARCs 的结构是通过可能的化学转化方法假设的；红霉素A到阿奇霉素A；其次，ARC 的假定结构在可接受的 ppm 误差限制 (±5 ppm) 内通过 HRMS 确认，然后进行 MS/MS 碎裂以识别特征性常见离子碎片并通过母离子扫描。图形概要