The identification of various proline‐containing dipeptides by implementing liquid chromatography‐electrospray ionization‐tandem mass spectrometry (LC‐ESI‐MS/MS) techniques is a challenging task. The ESI‐MS/MS spectra of protonated molecules [M + H]⁺ display a single dominant product ion, representing the pyrrolidinyl ring (m/z 70.0652). This lack of ESI‐MS/MS information leads to unavoidable ambiguity in the structure of the dipeptide. We demonstrate how structural information can be obtained instantaneously through ESI‐MS/MS fragmentation of the accompanied sodium adducts [M + Na]⁺ or alternatively by ESI‐MS/MS fragmentation of their carbamate derivatives. Both strategies are based on altering the charge distribution during fragmentation, promoting rich fragmentation patterns and enabling reliable structural elucidation.

中文翻译：

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液相色谱电喷雾电离串联质谱法分析含脯氨酸的二肽的结构分析策略

通过液相色谱-电喷雾串联质谱（LC-ESI-MS / MS）技术鉴定各种含脯氨酸的二肽是一项艰巨的任务。质子化分子[M + H] ⁺的ESI-MS / MS谱图显示一个主要的副产物离子，代表吡咯烷基环（m / z 70.0652）。ESI-MS / MS信息的缺乏导致二肽结构不可避免的歧义。我们演示了如何通过伴随的钠加合物[M + Na] ^+的ESI-MS / MS裂解即时获得结构信息或者通过ESI-MS / MS对其氨基甲酸酯衍生物进行裂解。两种策略都基于在碎片化过程中改变电荷分布，促进丰富的碎片化模式并实现可靠的结构阐明。