質量分析: 概要

Mass spectrometry is an analytical technique used to determine the molecular weight of a molecule.

A high-energy electron beam that strikes the molecule can displace an electron. Apart from electron impact ionization, alternative methods for sample ionization include chemical ionization and electrospray ionization.

Ionization leads to the formation of a parent molecular ion. It is a radical cation species with one unpaired electron and a 1+ positive charge.

Since the mass of the electron is negligible, the molecular weights of the molecular ion and its parent molecule are comparable. Here, the loss of an electron from the molecule weakens some bonds in the molecule.

Eventually, the molecular ion fragments into cations, radicals, neutral molecules, and other low-molecular-weight radical cations. The cleavage occurs at the weak bonds to produce relatively stable fragments.

In mass spectrometry, the individual fragments are separated and weighed. This information is used to reconstruct the molecular weight, structure, and molecular formula of the native molecule.