School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Life Sciences Mass Spectrometry, Quai Ernest-Ansermet 30, 1211 Geneva 4, Switzerland.
Anal Bioanal Chem. 2012 Mar;402(8):2555-64. doi: 10.1007/s00216-011-5444-y. Epub 2011 Oct 18.
The liquid chromatography-mass spectrometry (LC-MS) analysis of complex samples such as biological fluid extracts is widespread when searching for new biomarkers as in metabolomics. The success of this hyphenation resides in the orthogonality of both separation techniques. However, there are frequent cases where compounds are co-eluting and the resolving power of mass spectrometry (MS) is not sufficient (e.g., isobaric compounds and interfering isotopic clusters). Different strategies are discussed to solve these cases and a mixture of eight compounds (i.e., bromazepam, chlorprothixene, clonapzepam, fendiline, flusilazol, oxfendazole, oxycodone, and pamaquine) with identical nominal mass (i.e., m/z 316) is taken to illustrate them. Among the different approaches, high-resolution mass spectrometry or liquid chromatography (i.e., UHPLC) can easily separate these compounds. Another technique, mostly used with low resolving power MS analyzers, is differential ion mobility spectrometry (DMS), where analytes are gas-phase separated according to their size-to-charge ratio. Detailed investigations of the addition of different polar modifiers (i.e., methanol, ethanol, and isopropanol) into the transport gas (nitrogen) to enhance the peak capacity of the technique were carried out. Finally, a complex urine sample fortified with 36 compounds of various chemical properties was analyzed by real-time 2D separation LC×DMS-MS(/MS). The addition of this orthogonal gas-phase separation technique in the LC-MS(/MS) hyphenation greatly improved data quality by resolving composite MS/MS spectra, which is mandatory in metabolomics when performing database generation and search.
在代谢组学中，当寻找新的生物标志物时，广泛采用液相色谱-质谱（LC-MS）分析复杂样品，如生物流体提取物。这种联用技术的成功在于两种分离技术的正交性。然而，经常会出现化合物共洗脱的情况，而质谱（MS）的分辨率不足（例如，等摩尔化合物和干扰的同位素簇）。讨论了不同的策略来解决这些情况，并以具有相同名义质量（即 m/z 316）的八种化合物（即溴马唑仑、氯丙嗪、氯硝西泮、芬迪林、氟西唑仑、奥沙西泮、羟考酮和扑疟喹啉）的混合物为例进行说明。在不同的方法中，高分辨率质谱或液相色谱（即 UHPLC）可以很容易地分离这些化合物。另一种技术，主要用于低分辨率 MS 分析仪，是差分离子迁移谱（DMS），其中根据其大小与电荷比在气相中分离分析物。详细研究了向传输气体（氮气）中添加不同极性改性剂（即甲醇、乙醇和异丙醇）以增强该技术的峰容量。最后，通过实时二维分离 LC×DMS-MS(/MS) 分析了加标有 36 种具有不同化学性质的复杂尿液样品。在 LC-MS(/MS) 联用中加入这种正交气相分离技术极大地改善了数据质量，通过解析复合 MS/MS 谱，这在代谢组学中执行数据库生成和搜索时是必需的。
