质谱法中正电离和负电离之间的差异

Thekey differencebetween positive and negative ionization in mass spectrometry is that thepositive ionization forms positively charged ions, whereas the negative ionization forms negatively charged ions.

质谱或MS技术分析al chemistry that measures the mass-to-charge ratio of ions. The end result of this technique comes as a mass spectrum that appears as a plot of intensity. Further, this plot is drawn as a function of the mass-to-charge ratio. For massspectrometry, the instrument we use is a mass spectrometer. When we introduce our sample into this instrument, sample molecules undergo电离. Here, choosing the proper ionization technique is very important because it has a great impact on the end result. If we use a试剂gas, e.g. ammonia, it will cause ionization of sample molecules to form either only positive ions or only negative ions, depending on the setup of the instrument.

内容

1.Overview and Key Difference
2.What is Positive Ionization in Mass Spectrometry
3.What is Negative Ionization in Mass Spectrometry
4.并排比较 - 表格形式的质谱中的正vs负电离
5.概括

What is Positive Ionization in Mass Spectrometry?

质谱中的阳性电离涉及形成阳性离子，以测定样品分子的质量与电荷比。我们称此为正离子模式在质谱法中。我们可以将这种阳性离子表示为M-H⁺. In this technique, we can detect ions in a high yield.

电离过程如下：

GH⁺+ M ⟶ MH⁺+ G

A good example of positive ionization ismethane电离。我们可以写下该电离的化学方程式，如下所示：

CH₄+ e ch ch₄⁺+ 2e ⟶ CH₃⁺+ H

What is Negative Ionization in Mass Spectrometry?

Negative ionization in mass spectrometry involves the formation of negative ions for the determination of the mass-to-charge ratio of the sample molecules. We call this negative ion mode in mass spectrometry. Further, we can denote this negative ion as M-H^–. In this technique, we can detect these ions in a high yield. The ionization process is as follows:

GH^–+ M ⟶ MH^–+ G

What is the Difference Between Positive and Negative Ionization in Mass Spectrometry?

质谱或MS技术分析al chemistry that measures the mass-to-charge ratio of ions. There are two ways of ionizing sample molecules to determine this ratio: positive ionization and negative ionization. The key difference between positive and negative ionization in mass spectrometry is that the positive ionization is the process that forms positively charged ions, whereas the negative ionization is the process that forms negatively charged ions. Furthermore, the general formula for positive ionization in mass spectrometry is GH⁺+ M ⟶ MH⁺+ G, while the general formula for negative mass spectrometry is GH^–+ M ⟶ MH^–+ G.

The following infographic summarizes the difference between positive and negative ionization in mass spectrometry.

摘要 - 质谱法中的正与负电离

质谱或MS技术分析al chemistry that measures the mass-to-charge ratio of ions. Moreover, positive ionization and negative ionization are the two ways of ionizing sample molecules to determine this ratio. In summary, the key difference between positive and negative ionization in mass spectrometry is that the positive ionization is the process that forms positively charged ions, whereas the negative ionization is the process that forms negatively charged ions.

Reference:

1.“Mass Spectrometry.” Wikipedia, Wikimedia Foundation, 30 Sept. 2019,Available here.
2. Large, Robert, and Hans Knof. “A Comparison of Negative and Positive Ion Mass Spectrometry.” Wiley Online Library, John Wiley & Sons, Ltd, 7 Apr. 2005,Available here.

Image Courtesy:

1. “ObwiedniaPeptydu” (GPL) viaCommons Wikimedia