Paper spray ionization mass spectrometry (PSI-MS) is a powerful technique for the direct analysis of complex samples with high performance but with highly simplified procedures. Herein PSI-MS has been optimized for the discrimination of commercial gasoline quality. For the purpose of increasing the ionization efficiency of gasoline samples, various solvents (e.g., methanol, ethanol, acetonitrile and isopropanol) were mixed with gasoline prior to PSI-MS analysis. The results demonstrated that a high polarity of applied solvent would lead to more information of gasoline samples in generated mass spectra, and 70% (v/v) of gasoline in gasoline/methanol admixtures gave the optimal condition. The optimized PSI-MS was then applied to discriminate commercial gasoline samples from different gas stations of four refining companies. It was found that there was much difference in the gasoline samples from different companies, and even for those from the same refining company but from different gas stations. Further studies of the fingerprinting of gasoline samples indicated that the components of gasoline samples from different gas stations but from one refining company varied significantly, suggesting that no comparable standards were implemented in the refining process of gasolines. Also, PSI-MS was applied to discriminate gasoline adulterated with diesel, and as low as 1% of diesel in gasoline could be detected. These results illustrate that PSI-MS is an alternative and sensitive methodology for rapid evaluation of gasoline quality.

中文翻译：

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纸喷雾质谱法用于区分商用汽油的质量

纸喷雾电离质谱法（PSI-MS）是一种用于对复杂样品进行直接分析的有力技术，具有高性能，但程序高度简化。在此，PSI-MS已针对区分商用汽油质量进行了优化。为了提高汽油样品的电离效率，可以使用各种溶剂（例如在进行PSI-MS分析之前，将甲醇，乙醇，乙腈和异丙醇）与汽油混合。结果表明，所施加溶剂的高极性将导致所生成质谱图中汽油样品的更多信息，而汽油/甲醇混合物中70％（v / v）的汽油给出了最佳条件。然后将优化的PSI-MS应用于区分来自四个炼油公司不同加油站的商业汽油样品。结果发现，来自不同公司的汽油样品差异很大，甚至来自同一精炼公司但来自不同加油站的汽油样品也存在很大差异。对汽油样品指纹图谱的进一步研究表明，来自不同加油站但来自一家精炼公司的汽油样品的成分差异很大，这表明在汽油精炼过程中没有实施可比标准。此外，PSI-MS还用于区分掺有柴油的汽油，并且汽油中的柴油含量低至1％。这些结果说明，PSI-MS是一种用于快速评估汽油质量的替代方法和敏感方法。