IMPROVED ELECTROSPRAY IONIZATION INTERFACE FOR CAPILLARY ZONE ELECTROPHORESIS - MASS-SPECTROMETRY
IMPROVED ELECTROSPRAY IONIZATION INTERFACE FOR CAPILLARY ZONE ELECTROPHORESIS - MASS-SPECTROMETRY
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DOI：
10.1021/ac00169a022
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发表时间：
1988-09-15
影响因子：
7.4
通讯作者：
UDSETH, HR
中科院分区：
文献类型：
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作者：
SMITH, RD;BARINAGA, CJ;UDSETH, HR
介绍了一种用于毛细管区带电泳-质谱（CZE-MS）的新型电喷雾电离界面。该界面使用护套流动液体在CZE末端进行电接触，从而定义了CZE和电喷雾场梯度。这使得电喷液的组成可以独立于CZE缓冲液进行控制，提供了以前不能使用的缓冲液（例如，水性和高离子强度缓冲液）的操作。界面运行与CZE流量无关；CZE毛细血管很容易更换，不需要额外的准备。由于电喷雾直接从CZE毛细管端发生，避免了额外的混合体积和金属表面，电泳分离效率似乎不受干扰。与电喷雾界面相关的死体积< 10 nL，对应于鞘层电极液体的典型流速< 0.1 s。用cse - ms分离季铵盐混合物和肾上腺素及相关胺。操作演示了高表面活性剂浓度，如所需的毛细管电析色谱。将其推广到其他毛细管电泳方法，如等速电泳和等电聚焦，似乎是可行的。最近，我们描述了基于电喷雾电离（ESI）界面的毛细管区带电泳（CZE）和质谱（MS）的结合（1,2）。CZE的高分离效率和ESI质谱的固有灵敏度相结合，可以很容易地获得超过105个理论板，检测限在原子孔范围内(2)。前面描述的CZE-MS界面有许多吸引人的特性，包括有效检测量可以忽略不计。电喷雾直接在CZE毛细管的末端产生，避免了任何可能导致柱外带扩展（由于层流）或分析物吸附的柱后区域。以前的电喷雾界面不需要任何额外的气体流动来辅助雾化，也不会出现与传统雾化方法中较大的液滴尺寸分布相关的问题(3)。这些问题包括需要“离轴”取样和灵敏度降低，因为大液滴中的分析物不能有效电离(3)。
A new etectrospray ionization Interface for capillary zone electrophoresis-mass spectrometry (CZE-MS) is described. The interface uses a sheath flow of liquid to make the electrical contact at the CZE terminus, thus defining both the CZE and electrospray field gradients. This allows the composition of the eiectrosprayed liquid to be controlled independently of the CZE buffer, providing operation with buffers that could not be used previously (eg, aqueous and high ionic strength buffers). The interface operation is independent of CZE flow rate; CZE capillaries are easily replaced and require no ad-ditional preparation. Since the electrospray occurs directly from the CZE capillary terminus, additional mixing volumes and metal surfaces are avoided and electrophoretic separa-tion efficiency appears unperturbed. The dead volume asso-ciated with the electrospray interface is< 10 nL, corre-sponding to< 0.1 s for typical flow rates of the sheath electrode liquid. CZE-MS separations for mixtures of quaternary phosphonium salts and for epinephrine and related amines are demonstrated. Operation is demonstrated with high surfactant concentrations, as required for capillary electroklnefic chro-matography. The extension to other capillary electrophoresis methods, such as isotachophoresls and isoelectric focusing, appears feasible.Recently we have described thecombination of capillary zone electrophoresis (CZE) and mass spectrometry (MS) based upon an electrospray ionization (ESI) interface (1, 2). The combination of the high separation efficiencies feasible with CZE and the inherentsensitivity of ESI mass spectrometry allowed in excess of 105 theoretical plates to be readily ob-tained, with detection limits inthe attomole range (2). The CZE-MS interface described previously had a number of attractive features, including the factthat the effective detection volume was negligible. The electrospray was created directly at theterminus of the CZE capillary, avoiding any postcolumn region that would contribute to extracolumn band spread (due to laminar flow) or analyte adsorption. The previous electrospray interface did not require any additional gas flow to assist nebulization and did not exhibit problems associated with the larger droplet size distribution from conventional nebulization methods (3). Suchproblems include the need to sample the electrospray “off-axis" and reduced sensitivity because the analyte in larger droplets will not be efficiently ionized (3).