NEW PICOGRAM DETECTION SYSTEM BASED ON A MASS-SPECTROMETER WITH AN EXTERNAL IONIZATION SOURCE AT ATMOSPHERIC-PRESSURE
NEW PICOGRAM DETECTION SYSTEM BASED ON A MASS-SPECTROMETER WITH AN EXTERNAL IONIZATION SOURCE AT ATMOSPHERIC-PRESSURE
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DOI：
10.1021/ac60328a035
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发表时间：
1973-01-01
影响因子：
7.4
通讯作者：
STILLWELL, RN
中科院分区：
文献类型：
--
作者：
HORNING, EC;HORNING, MG;STILLWELL, RN
具有外部电离源的新型质谱仪可用于检测皮克量的生物感兴趣的化合物。该源包含63 Ni箔，并且处于大气压下。样品在选定的常用溶剂中以流动气流引入。正离子是由一系列复杂的离子分子反应形成的.样品的电离反应可能涉及质子转移或电荷转移。负离子通过热电子的共振或解离捕获或通过离子-分子相互作用形成。在有利的情况下（在反应室壁上吸附很少），单离子监测可检测到5-10皮克，扫描质谱可检测到25皮克。GC-MS-COM（气相色谱-质谱-计算机）型分析系统为药物代谢、毒理学和许多涉及人体代谢途径的问题的研究提供了最有力的研究手段。然而，这些系统仍处于发展的早期阶段，它们的能力更多地受到历史调查模式的限制，而不是技术限制。这些系统中的质谱仪通常基于不再适用的设计说明。样本量在以前并不是一个重要的问题;现在，检测的高灵敏度往往是最重要的。该系统的功能是检测和定量流动气流中的分子实体，但质谱仪主要设计为具有内部源和多泵组件的高真空仪器。我们已经启动了一个有三个目标的计划：定义在大气压下发生的生物感兴趣的化合物的电离反应，由来自63 Ni的电子而不是来自“加热的灯丝”的电子引发;定义设计为检测器并以连续采样的方式操作的MS-COM系统的特性。
A novel mass spectrometer with an external ionization source can be used to detect picogram quantities of compounds of biologic interest. The source contains a 63Ni foil, and is at atmospheric pressure. Samples are introduced in a flowing gas stream in selected common solvents. Positive ions are formed by a complex series of ion moleculereactions. The ionizationreaction for the sample may involve either proton transfer or charge transfer. Negative ions are formed by either resonance or dissociative capture of thermal electrons, or by ion-molecule interactions. In a favorable case(very little adsorp-tion on the reaction chamberwalls), 5-10 picograms could be detected by single ion monitoring, and a scanned mass spectrum could be obtained with as little as 25 picograms. The potential uses include incorpora-tion into LC-MS-COM and GC-MS-COM analytical systems.Analytical systems of the GC-MS-COM (gas chromatograph-mass spectrometer-computer) type provide the most powerful means of investigation now available for studies of drug metabolism, in toxicology and in many problems involving human metabolic pathways. These systems are still in an early stage of development, however, and their capabilities are restricted more by histori-cal patterns of investigation than by technological limita-tions. Mass spectrometers in these systems are usually based on design considerationswhich no longer apply. Sample size was not an important matter earlier; now, high sensitivity in detection is often of paramount impor-tance. The function of the system is to detect and quant-ify molecular entities in a flowing gas stream, but mass spectrometers are designed largely as high vacuum instru-ments with internal sources and multiple pump assem-blies. We have initiated a program with three objectives: to defineionization reactions occurring at atmospheric pressure for compoundsof biologic interest, initiated by electrons from 63Ni rather than from a'heated filament; to define the characteristics of an MS-COM system designed as a detector and operating with continuous sampling of a