Direct analysis in real time (DART) mass spectrometry is a recently developed innovative technology, which has shown broad applications for fast and convenient analysis of complex samples. Due to the ease of sample preparation, we have recently initiated an investigation of the feasibility of detecting nucleotides and nucleosides using the DART-AccuTOF instrument, which we will refer to as the DART mass spectrometer. Our experimental results reveal that the ions representing the intact molecules of nucleotides are not detectable in either positive-ion or negative-ion mode. Instead, all four natural nucleotides fragment in the DART ion source, and a common fragment ion, [C₅H₅O]⁺ (1), is observed, which is probably formed via multiple-elimination reactions. Interestingly, 1 can form adducts with nucleobases in different molar ratios in the DART ion source. In contrast to nucleotides, the ions representing the intact molecules of nucleosides are detected in both positive-ion and negative-ion mode using DART mass spectrometry. Surprisingly, the fragmentation pattern of nucleosides is different from that of nucleotides in the DART ion source. In the cases of nucleosides (under positive-ion conditions), the production of 1 is not observed, indicating that the phosphate group plays an important role for the multiple eliminations observed in the spectra of nucleotides. The in-source reactions described in the present work show the complexity of the conditions in the DART ion source, and we hope that our results illustrate a better understanding about DART mass spectrometry.

实时直接分析 (DART) 质谱法是最近开发的一项创新技术，在快速方便地分析复杂样品方面显示出广泛的应用。由于样品制备容易，我们最近开始研究使用 DART-AccuTOF 仪器检测核苷酸和核苷的可行性，我们将其称为 DART 质谱仪。我们的实验结果表明，在正离子或负离子模式下都无法检测到代表完整核苷酸分子的离子。相反，DART 离子源中的所有四种天然核苷酸和一个常见的碎片离子 [C ₅ H ₅ O] ⁺(1), 被观察到，这可能是通过多重消除反应形成的。有趣的是，1 可以与 DART 离子源中不同摩尔比的核碱基形成加合物。与核苷酸相比，代表完整核苷分子的离子使用 DART 质谱法在正离子和负离子模式下进行检测。令人惊讶的是，核苷的断裂模式与 DART 离子源中的核苷酸不同。在核苷的情况下（在正离子条件下），没有观察到 1 的产生，表明磷酸基团在核苷酸光谱中观察到的多重消除中起重要作用。当前工作中描述的源内反应显示了 DART 离子源条件的复杂性，