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首页> 外文期刊>Journal of mass spectrometry: JMS >Analysis of deprotonated acids with silicon nanoparticle-assisted laser desorption/ ionization mass spectrometry
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Analysis of deprotonated acids with silicon nanoparticle-assisted laser desorption/ ionization mass spectrometry

机译：硅纳米粒子辅助激光解吸/电离质谱分析去质子酸

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Chemically modified silicon nanoparticles were applied for the laser desorptionegative ionization of small acids. A series of substituted sulfonic acids and fatty acids was studied. Compared to desorption ionization on porous silicon (DIOS) and other matrix-less laser desorption/ionization techniques, silicon nanoparticle-assisted laser desorption/ionization (SPALDI) mass spectrometry allows for the analysis of acids in the negative ion mode without the observation of multimers or cation adducts. Using SPALDI, detection limits of many acids reached levels down to 50 pmol/?μl. SPALDI of fatty acids with unmodified silicon nanoparticles was compared to SPALDI using the fluoroalkyl silylated silicon powder, with the unmodified particles showing better sensitivity for fatty acids, but with more low-mass background due to impurities and surfactants in the untreated silicon powder. The fatty acids exhibited a size-dependent response in both SPALDI and unmodified SPALDI, showing a signal intensity increase with the chain length of the fatty acids (C12-C18), leveling off at chain lengths of C18-C22. The size effect may be due to the crystallization of long chain fatty acids on the silicon. This hypothesis was further explored and supported by SPALDI of several, similar sized, unsaturated fatty acids with various crystallinities. Fatty acids in milk lipids and tick nymph samples were directly detected and their concentration ratios were determined by SPALDI mass spectrometry without complicated and time-consuming purification and esterification required in the traditional analysis of fatty acids by gas chromatography (GC). These results suggest that SPALDI mass spectrometry has the potential application in fast screening for small acids in crude samples with minimal sample preparation.
机译：化学改性的硅纳米颗粒用于小酸的激光解吸/负电离。研究了一系列取代的磺酸和脂肪酸。与多孔硅上的解吸电离（DIOS）和其他无基质激光解吸/电离技术相比，硅纳米粒子辅助激光解吸/电离（SPALDI）质谱法可在负离子模式下分析酸而无需观察多聚体或阳离子加合物。使用SPALDI，许多酸的检测限达到了50 pmol /？μl的水平。将未改性硅纳米颗粒的脂肪酸SPALDI与使用氟烷基甲硅烷基化硅粉的SPALDI进行了比较，未改性颗粒对脂肪酸的敏感性更高，但由于未处理的硅粉末中的杂质和表面活性剂，其本底质量较低。脂肪酸在SPALDI和未修饰的SPALDI中均显示出大小依赖性响应，显示信号强度随脂肪酸（C12-C18）链长的增加而增加，在C18-C22链长时趋于平稳。尺寸效应可能是由于长链脂肪酸在硅上的结晶所致。 SPALDI进一步探索并支持了这种假说，该假说是几种大小相似，具有不同结晶度的不饱和脂肪酸。直接检测牛奶脂质和tick若虫样品中的脂肪酸，并通过SPALDI质谱法测定其浓度比，而无需通过气相色谱（GC）进行传统的脂肪酸分析，而需要进行复杂且费时的纯化和酯化反应。这些结果表明，SPALDI质谱技术可用于以最少的样品前处理快速筛查粗样品中的小酸。

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