Mass Discrimination and Analysis in Mass Spectroscopy

质谱基本上涉及中性分子的电离和碎片化，然后是基于电荷物种的电荷与质量（m/z）比率进行分组，以进行检测和定量。本文讨论了歧视电离质量片段及其分析的常见选择。

四极群分析仪

A quadrupole mass analyzer comprises of four parallel rods assembled in a square shaped arrangement. The ionized molecules are directed through the centre of the square formed by the rods. A combination of DC and RF potentials is applied to the diagonally opposite rods thereby permitting only selected m/z ratio ions to pass and reach the detector. The other ions strike the rods get destroyed and are unable to reach the detector.

Quadrupole systems offer a cost-effective mass discrimination option. The reproducibility is good but other mass analyzers would be required for applications requiring higher resolutions and pulsed ionization sources. Due to their lower cost and simplicity quadrupole systems are found in majority of bench top GC/ MS and LC/MS systems.

磁性扇区分析仪

磁性扇区分析仪利用永久磁铁或电磁体的磁场来解决电离质量片段。磁场沿垂直方向施加到分子离子的流动路径。该场在圆形弧中偏转离子，从而解决不同的质量。除了磁场外的电离分子外，还可以实现较高的分辨率。在“反向几何”布置中，磁性部门先于电部门。电场通常保持固定值，并且磁场的变化以扫描不同的质量以给电离物种充电。较大或较小的m/z值的离子撞到了管子并被破坏。

磁性扇形系统提供高度的可重复性和分辨率以及高动态质量范围。但是，这样的系统的尺寸很大，成本也更高。理想情况下，此类分析仪可用于准确的质量测量和确定分析物的同位素比组成。

飞行量分析仪的时间

A uniform field is applied to all ions at the same time permitting them to accelerate down the length of the flight tube. Lighter ions travel faster so as to reach the detector before the heavier ones. The mass to charge ratios are discriminated by the time taken to reach the detector. Such arrangements also help detect mass accurately and are well suited for pulsed ionization sources such as MALDI. The systems provide high mass range among different available mass analyzers.

四极离子陷阱

离子陷阱还包括一个圆环电极，除两个端盖外，它们共同形成一个限制空间，在该空间中，在电磁场的帮助下被捕获。然后对RF和DC电势进行扫描以依次弹出不同的质量质量与充电比率片段至以序列到达检测器。

离子陷阱系统用作紧凑型基准质量分析仪。但是，动态范围是有限的，对离子物种的定量很差。

群众分析仪提供了自己的特征特征，可用于不同的质谱分析应用。一些典型的应用程序将随后采用。