Chemistry – Analytical techniques | e-Consult

Molecular Ion Peak (m/z = 120): The molecular ion peak represents the intact molecule that has been ionized. The *m/z* value indicates the mass-to-charge ratio of the molecular ion. Therefore, the molecular ion has a mass of 120 amu and a charge of +1. This means the original molecule has a mass of 120 amu. This peak confirms the molecular weight of the compound.

Fragment Peak (m/z = 44): The fragment peak at *m/z* = 44 indicates a fragment of the original molecule that has been formed during the ionization and fragmentation process. The difference in mass between the molecular ion (120 amu) and the fragment ion (44 amu) is 76 amu. This mass difference corresponds to a specific fragment that has broken off from the molecule. The fragmentation pattern provides clues about the structure of the molecule. For example, a loss of a specific group (e.g., -CH3, -OH) can indicate the presence of that functional group in the molecule.

Diagram (Illustrative):

The process of ionization typically involves electron impact ionization (EI). A beam of high-energy electrons collides with the sample molecules, causing them to lose an electron and form positive ions (molecular ions). These ions are then accelerated and passed through a mass analyzer, which separates them based on their *m/z* ratio. Fragmentation occurs as the ions are accelerated and collide with the analyzer crystals, leading to the formation of various fragment ions. The resulting mass spectrum displays the abundance of ions as a function of their *m/z* values.

[A diagram showing electrons colliding with molecules, forming ions, and then being separated by a mass analyzer would be included here. This is not possible to render in plain text.]