Mass Spec Explanation in HTML
Mass spectrometry can help determine the molecular formula and weight of a compound as well as provide isotope abundance data. Within a magnetic field the angle of deflection of charged particles is used to discover the relative masses of molecular fragments and ions. Several peaks are due to the contribution of Isotopes. An Isotope refers to an atom having the same atomic number but a deferent number of neutrons, subtracting or adding mass. The mass spectrum of methyl chloride has a base peak at m/z=49 consisting of the most abundant Ion at 100% abundance.
It also has a molecular ion peak at m/z=84 consisting of the molecular weight of methyl chloride at 80% abundance. By subtracting the base peak from the molecular Ion peak, It can be determined that the resulting 35 corresponds to CLC. The difference of other molecular fragments can be looked at to verify chlorine’s presence such as and corresponding to the CLC Isotope. The [M*2] rule also Identifies the CLC Isotope when looking at m/z=84, 86 and 86, 88. Each urn/z peak can represent a variety of different molecular mass fragments.
The peaks arm=86 and 88 only have and abundance respectively, since both peaks are the results of isotopes. The CLC isotope has a 24% abundance naturally and ICC has a 1% abundance naturally. These low abundance percentages contribute to the smaller intensities of the m/z=86 and 88 peaks. While m/z=86 can be found with only one isotope of CLC, m/z=88 must contain at least two CLC isotopes making the intensity of its peak even less. Mass spectroscopy may identify a compound’s fragments and isotopes, but it also determines the purities of products.