Crown ether dopant to reduce ion suppression and improve detection in the liquid microjunction surface sampling probe

IF 1.8 3区化学 Q4 BIOCHEMICAL RESEARCH METHODS Rapid Communications in Mass Spectrometry Pub Date : 2024-08-19 DOI:10.1002/rcm.9889

Haidy Metwally, Jian Yu, Rachel Theriault, Jennifer L. Kolwich, Randy Ellis, Avena C. Ross, Richard D. Oleschuk

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Abstract

Rationale

Sodium and potassium are required in agar media for the growth of some microorganisms (e.g., marine bacteria). However, alkali cations are a significant source of contamination for mass spectrometry causing ion suppression and adduct formation. Conventionally, salts can be removed before mass spectrometric analysis with appropriate and often lengthy sample preparation. The direct mass spectrometric sampling of bacterial colonies grown on agar media seeks to minimize or eliminate sample preparation to improve workflow. However, this may exacerbate ion suppression and contamination since these metal cations will degrade spectral quality and limit the rapid profiling of microbial metabolites. Different approaches are needed to sequester sodium and potassium ions to minimize unwanted background interferences. Herein, we use crown ethers (CEs) in combination with a liquid microjunction surface sampling probe (LMJ-SSP) to directly sample the surface of the bacterial colonies from two marine bacteria species (Pseudoalteromonas rubra DSM6842 and Pseudoalteromonas tunicata DSM 14096). CEs (e.g., 18-crown-6 or 15-crown-5) are added to the carrier solvent of the LMJ-SSP, the chemical noise is reduced, and spectra are easier to interpret.

Methods

The liquid microjunction formed at the tip of LMJ-SSP was used to directly touch bacterial colonies on agar. The carrier solvent was either methanol (100%) or methanol: H₂O (50:49.9%) with or without 0.01% CEs. Information-theoretic measures are employed to investigate qualitative changes between spectra before and after adding CEs.

Results

Our work demonstrates the capability of CEs to reduce background interferences within the direct profiling of bacterial colonies from agar plates. The data obtained from both P. rubra DSM6842 and P. tunicata DSM 14096 show that CEs can be used to mitigate the salty background and improve compound detection.

Conclusion

Our approach can be implemented in natural product discovery using LMJ-SSP to allow fast and accurate detection of interesting/novel compounds.

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冠醚掺杂剂可减少离子抑制，提高液体微结表面取样探针的检测能力。

理由：某些微生物（如海洋细菌）的生长需要琼脂培养基中的钠和钾。然而，碱阳离子是质谱分析的一个重要污染源，会导致离子抑制和加成物的形成。传统的方法是在质谱分析前通过适当的、通常需要很长时间的样品制备来去除盐分。对生长在琼脂培养基上的细菌菌落直接进行质谱采样，可最大限度地减少或消除样品制备过程，从而改进工作流程。然而，这可能会加剧离子抑制和污染，因为这些金属阳离子会降低光谱质量，限制微生物代谢物的快速分析。需要采用不同的方法来封存钠离子和钾离子，以尽量减少不必要的背景干扰。在此，我们将冠醚（CE）与液态微结表面采样探针（LMJ-SSP）结合使用，直接对两种海洋细菌（红假交单胞菌 DSM6842 和红假交单胞菌 DSM14096）的细菌菌落表面进行采样。在 LMJ-SSP 的载体溶剂中加入 CE（如 18-冠-6 或 15-冠-5），可降低化学噪音，使光谱更容易解读：方法：用 LMJ-SSP 顶端形成的液体微结直接接触琼脂上的细菌菌落。载体溶剂为甲醇（100%）或甲醇：水（50:49.9%），含或不含 0.01% CEs。我们采用信息论方法研究了添加 CEs 前后光谱之间的质变：我们的工作证明了 CEs 在直接分析琼脂平板细菌菌落时减少背景干扰的能力。从 P. rubra DSM6842 和 P. tunicata DSM 14096 获得的数据表明，CEs 可用于减轻咸味背景，提高化合物检测水平：结论：我们的方法可用于使用 LMJ-SSP 进行天然产品发现，从而快速准确地检测出有趣/新颖的化合物。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Rapid Communications in Mass Spectrometry 化学-分析化学

CiteScore

4.10

自引率

5.00%

发文量

219

审稿时长

2.6 months

期刊介绍： Rapid Communications in Mass Spectrometry is a journal whose aim is the rapid publication of original research results and ideas on all aspects of the science of gas-phase ions; it covers all the associated scientific disciplines. There is no formal limit on paper length ("rapid" is not synonymous with "brief"), but papers should be of a length that is commensurate with the importance and complexity of the results being reported. Contributions may be theoretical or practical in nature; they may deal with methods, techniques and applications, or with the interpretation of results; they may cover any area in science that depends directly on measurements made upon gaseous ions or that is associated with such measurements.