Development and Application of a Dual Detection Concept (Amperometry-Mass Spectrometry) for Capillary Electrophoresis

医疗和环境应用中样品的高度复杂性以及在较短时间尺度内分析数量的增加要求强大的仪器分析系统的新发展。结合双重检测方法的分离技术能够在一次运行中产生大量的信息，因为分析物的分离和两种检测方法的组合数据。在这个项目中，毛细管电泳（CE）的双重检测概念-一种基于带电物质在电场中的迁移的分离方法，允许短的分离时间和低样品和溶剂的消耗-安培检测（AD）和质谱（MS）。由于在毛细管电泳中出现的低样品量时具有无与伦比的灵敏度，因此AD非常适合于毛细管电泳的定量。然而，不可能识别物质或发现相互作用。相比之下，质谱法可以根据未知物质的质谱和相应的分子式来识别未知物质。然而，使用CE-MS获得的检测限（取决于分析物）通常在10-6 M范围内，这比目前使用CE-AD获得的检测限大约高出两个数量级。使用最新一代的电位器，AD的限制甚至可以降低。此外，由于电喷雾电离的复杂性，通常必须基于同位素标记标准的使用，这可能是昂贵的，并不总是可用的。因此，CE-AD/MS概念提供了补充的数据和信息。由于两个检测器的破坏性，不能一个接一个地放置，因此必须开发一种新的概念，将高压驱动的流体通过分离毛细管分离到两个检测器上。CE-AD/MS优化耦合装置的仪器开发应该能够精确控制两种微流控流。二茂铁衍生物可以作为计算分析物有效迁移率的内标。通过这种方式，即使迁移时间发生变化，也可以实现AD和MS信号的明确分配。样品中被分析物的量可采用AD法进行定量，灵敏度高，易于操作，同时可采用质谱法进行物质鉴定和峰纯度验证，避免错误结果。此外，由于互补检测原理，用一个检测器无法检测到的物质通常可以用另一个检测器检测到，从而可以分析复杂样品中更大范围的成分。因此，新的CE-AD/MS概念提供了高信息密度和通用性，因此它可以用于复杂样品的分析。

The high complexity of samples in medical and environmental applications and the increasing number of analyses in shorter time-scales demand new developments of powerful instrumental analytical systems. Separation techniques coupled to dual detection methods are capable of generating a large amount of information in one run because of the separation of analytes and the combined data from both detection methods.In this project, a dual detection concept for hyphenation of capillary electrophoresis (CE) - a separation method based on the migration of charged species in an electrical field, which allows for short separation times and low consumption of samples and solvents - with amperometric detection (AD) and mass spectrometry (MS) is planned. AD is well suited for quantification in capillary electrophoresis due to its unmatched sensitivity at low amounts of sample as they occur in capillary electrophoresis. However, it is not possible to identify substances or to spot comigrations. In contrast, MS can identify unknown substances based on their mass spectra and corresponding molecular formulas. However, the limits of detection (depending on the analytes) obtained with CE-MS are typically in the range of 10-6 M which is about two magnitudes of order higher than currently obtained in CE-AD. With the newest generation of potentiostats the limits of AD can even be lowered. In addition, due to the complexity of electrospray ionization quantification has usually to be based on the use of isotope labelled standards, which can be expensive and are not always available. Thus, the CE-AD/MS concept provides complementary data and information.As both detectors cannot be placed one after the other due to their destructive properties, a new concept has to be developed to split the high voltage-driven flow through the separation capillary onto both detectors. The instrumental development of an optimized coupling device for CE-AD/MS should enable a precise control of both microfluidic flow streams. Ferrocene derivatives can serve as internal standards to calculate effective mobilities of the analytes. In this way an unambiguous assignment of AD and MS signals can be achieved even if migration times tend to shift.The amount of analyte in the sample can be quantified by AD, which is very sensitive and easy to handle, while substance identification and peak purity can be validated by MS to avoid false results. Additionally, due to the complementary detection principles, substances that cannot be detected with one detector can often be detected with the other so that a broader range of components in complex samples can be analyzed.Thus, the novel CE-AD/MS concept provides a high information density and universality so that it can contribute to the analysis of complex samples.