After fragmentation of the molecule in a mass spectrometer, cations with the lowest charge to mass ratio are deflected least by the magnetic field, while those with the highest charge to mass ratio are deflected most. The instrument scans over the range of charge to mass ratio, the mass spectrum, varying either the initial particle acceleration or the magnetic field to cause a particular charge to mass ratio to be focused onto the detector.
The most intense peak is the base peak. The base peak is not always the molecular ion peak because some compounds are very prone to fragmentation. This is especially true when fragments can be formed that are especially stable carbocations, such as the benzyl cation.
Small peaks one or two units adjacent to a large peak correspond to the presence of isotopes of elements present. Isotopic clusters are especially prominent in substances containing chlorine or bromine because of the high relative abundance of these isotopes.
The most intense peak is the base peak. The base peak is not always the molecular ion peak because some compounds are very prone to fragmentation. This is especially true when fragments can be formed that are especially stable carbocations, such as the benzyl cation.
Small peaks one or two units adjacent to a large peak correspond to the presence of isotopes of elements present. Isotopic clusters are especially prominent in substances containing chlorine or bromine because of the high relative abundance of these isotopes.
 The WikiPremed MCAT Course is a comprehensive course in the undergraduate level general sciences. Undergraduate level physics, chemistry, organic chemistry and biology are presented by this course as a unified whole within a spiraling curriculum. Please read our policies on Privacy and Shipping & Returns. Contact Us. MCAT is a registered trademark of the Association of American Medical Colleges, which does not endorse the WikiPremed Course. WikiPremed offers the customers of our publications or our teaching services no guarantees regarding eventual performance on the MCAT.
WikiPremed is a trademark of Wisebridge Learning Systems LLC. The work of WikiPremed is published under a Creative Commons Attribution NonCommercial ShareAlike License. There are elements of work here, such as a subset of the images in the archive from WikiPedia, that originated as GNU General Public License works, so take care to follow the unique stipulations of that license in printed reproductions. |