Application of matrix-assisted laser desorption/ionization in the studies of phosphotungstic acid

IF 1.8 3区化学 Q4 BIOCHEMICAL RESEARCH METHODS

Rapid Communications in Mass Spectrometry Pub Date : 2024-07-14 DOI:10.1002/rcm.9870

Irina V. Minenkova, Viacheslav V. Lebedev, Alexey K. Buryak

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引用次数: 0

Abstract

Rationale

Phosphorotungstic acid (PTA) has many applications, especially in the field of catalysis, due to its structural properties. However, the structure of PTA is studied mainly using theoretical methods. Matrix-assisted laser desorption/ionization (MALDI) has the potential to be an effective method for the experimental study of heteropolyacids. Limitations of MALDI are the high molecular weight of the particles and the complex distribution of isotopic peak intensities. Both problems can be solved by automatically identifying observed signals by generating hypothetical molecular formulas and estimating their isotopic distributions.

Methods

Phosphotungstic acid was studied under conditions of laser desorption/ionization in the absence and in the presence of the matrix. Three types of matrices were used: 2,5-dihydroxybenzoic acid in water, α-cyano-4-hydroxycinnamic acid in acetonitrile, and sinapic acid (SA) in tetrahydrofuran. Part of the peaks in the resulting mass spectra was identified using in-house developed software that implements the automated isotopic distribution brute force.

Results

The most informative mass spectra were obtained using SA as the matrix, which enabled the detection of particles containing PTA dimers for the first time. The compositions of particles incorporating PTA dimers were determined in an automated manner and can be written as [H₃PW₁₂O₄₀]₂·2H₂O (m/z = 5791.2 Da) and [H₃PW₁₂O₄₀]₂·4H₂O (m/z = 5836.5 Da). Other observed species included (WO₃)_n·PO₃⁻, HPO₂·(WO₃)_n, and WO₂·(WO₃)_n clusters, with the latter containing W in mixed oxidation states.

Conclusions

The combined use of MALDI and an automated identification procedure provided valuable experimental data on the structure and fragmentation of phosphotungstic acid. To the best of our knowledge, this study was the first to report on particles containing phosphotungstic acid dimers.

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基质辅助激光解吸/电离技术在磷钨酸研究中的应用。

理由磷钨酸（PTA）因其结构特性而有很多应用，特别是在催化领域。然而，对 PTA 结构的研究主要采用理论方法。基质辅助激光解吸/电离（MALDI）有可能成为实验研究杂多酸的有效方法。MALDI 的局限性在于颗粒的高分子量和同位素峰强度的复杂分布。通过生成假设的分子式并估算其同位素分布，自动识别观察到的信号，可以解决这两个问题：方法：在无基质和有基质的激光解吸/电离条件下对磷钨酸进行了研究。使用了三种基质：水溶液中的 2,5-二羟基苯甲酸、乙腈中的α-氰基-4-羟基肉桂酸和四氢呋喃中的山奈酸（SA）。质谱中的部分峰值是通过内部开发的软件识别的，该软件实现了自动同位素分布蛮力：结果：以 SA 为基质得到的质谱信息量最大，首次检测到了含有 PTA 二聚体的颗粒。含有 PTA 二聚体的颗粒的成分是自动测定的，可写成 [H3PW12O40]2-2H2O (m/z = 5791.2 Da) 和 [H3PW12O40]2-4H2O (m/z = 5836.5 Da)。观察到的其他物种包括 (WO3)n-PO3-、HPO2-(WO3)n 和 WO2-(WO3)n 簇，后者含有混合氧化态的 W：MALDI 和自动识别程序的结合使用为磷钨酸的结构和碎片提供了宝贵的实验数据。据我们所知，这项研究首次报道了含有磷钨酸二聚体的颗粒。

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.