Chapter 24, Problem 6Q

Interpretation Introduction

Interpretation:

The molecular structure of the compound and the fragments responsible for the $\text{m/z}$ value of 120, 44 and 91 should be determined.

Concept introduction:

Mass spectrometry is an important spectroscopic method to determine the molecular weights and molecular formulas of the compounds. It also can help in the identification of compound or determination of its structure.

A mass spectrograph is plotted between the intensity of ions on the y-axis and $\text{m/z}$ on the x-axis. Mass spectrometry works as follows:

• A sample is converted into a gaseous ion by an ionization technique in the mass spectrometer.
• Then on the basis of mass-to-charge $\left(\text{m/z}\right)$ ratios, gaseous ions are arranged.
• These ions generate electric current at the detector and a mass spectrum is formed.

To assign the molecular weights to compounds the rule of thirteen is utilized in mass spectrometry. Thirteen here is obtained by the addition of the mass of carbon and hydrogen.