Zhang Wei, Gulersonmez M Can, Hankemeier Thomas, Ramautar Rawi
Division of Analytical Biosciences, Leiden Academic Center for Drug Research, Leiden University.
Division of Analytical Biosciences, Leiden Academic Center for Drug Research, Leiden University;
J Vis Exp. 2016 Oct 1(116):54535. doi: 10.3791/54535.
In metabolomics, a wide range of analytical techniques is used for the global profiling of (endogenous) metabolites in complex samples. In this paper, a protocol is presented for the analysis of anionic and cationic metabolites in biological samples by capillary electrophoresis-mass spectrometry (CE-MS). CE is well-suited for the analysis of highly polar and charged metabolites as compounds are separated on the basis of their charge-to-size ratio. A recently developed sheathless interfacing design, i.e., a porous tip interface, is used for coupling CE to electrospray ionization (ESI) MS. This interfacing approach allows the effective use of the intrinsically low-flow property of CE in combination with MS, resulting in nanomolar detection limits for a broad range of polar metabolite classes. The protocol presented here is based on employing a bare fused-silica capillary with a porous tip emitter at low-pH separation conditions for the analysis of a broad array of metabolite classes in biological samples. It is demonstrated that the same sheathless CE-MS method can be used for the profiling of cationic metabolites, including amino acids, nucleosides and small peptides, or anionic metabolites, including sugar phosphates, nucleotides and organic acids, by only switching the MS detection and separation voltage polarity. Highly information-rich metabolic profiles in various biological samples, such as urine, cerebrospinal fluid and extracts of the glioblastoma cell line, can be obtained by this protocol in less than 1 hr of CE-MS analysis.
在代谢组学中，广泛的分析技术被用于对复杂样品中的（内源性）代谢物进行全局分析。本文介绍了一种通过毛细管电泳-质谱联用（CE-MS）分析生物样品中阴离子和阳离子代谢物的方法。CE非常适合分析高极性和带电代谢物，因为化合物是根据其电荷与大小之比进行分离的。一种最近开发的无鞘接口设计，即多孔尖端接口，用于将CE与电喷雾电离（ESI）质谱联用。这种接口方法能够有效利用CE固有的低流速特性与质谱联用，从而实现对多种极性代谢物类别的纳摩尔检测限。本文介绍的方法基于在低pH分离条件下使用带有多孔尖端发射器的裸熔融石英毛细管，用于分析生物样品中的多种代谢物类别。结果表明，仅通过切换质谱检测和分离电压极性，相同的无鞘CE-MS方法即可用于分析阳离子代谢物（包括氨基酸、核苷和小肽）或阴离子代谢物（包括糖磷酸盐、核苷酸和有机酸）。通过该方法，在不到1小时的CE-MS分析中，即可获得尿液、脑脊液和胶质母细胞瘤细胞系提取物等各种生物样品中信息丰富的代谢图谱。
