Mass Spectrometry - PowerPoint Presentation Example

al affiliation Mass Spectrometry Mass spectrometry is an analytical method of determining the molecular masses of compounds by producing spectra, which are used to determine the isotropic or elemental signature of a sample. The spectrum also is used to find the masses of particles and thereafter, the masses of molecules. The chemical structures of molecules can thus be drawn. The process is done by creating charged particles from molecules. The sample which may be solid, liquid or gas is charged by bombarding it with electrons.

This results into the molecule sample disintegrating as charged fragments. The ions are then separated according to charge to mass ratio. They thus deflect such that those with the same mass to charge ratio experience the same deflection. The results are displayed spectra. The molecules or atoms in the sample are identified by comparing the found masses with the known masses. Mass spectrometry technology finds a wide range of applications such as in identifying unknown compounds, determining isotropic composition of element in a molecule and elucidating the structure of a compound.

The gas chromatograph mass spectrometer, an instrument used for mass spectrometry, consists of there major parts. 1. Ionizer2. Ion analyse3. Detector The ionizer: - This is where ionisation of the sample material occurs. The electron impact ionisation is caused to bombard with the gas molecules from the gas chromatograph. The ion analyser: - fragment ions as well as molecular ions are accelerated by manipulation of the charged particles. The mass analysis uses negative and positive voltages to control the path of the ions.

Uncharged molecules and fragments are pumped away. The paths the ions assume are determined by their charge to mass ratio.Detector: they work by producing an electrical signal when hit by an ion. The mass detector records the abundance of individual mass to charge ratios, after sorting by the mass analyser. Ionisation occurs at the ionizer stage. For soft ionisation, the bombardment which is carried out, impact very little residual energy onto the sample molecule resulting into very little fragmentation.

Hard ionisation processes result into high residual energy into the sample material thereby leading t large fragmentation. Time-of-flight analyser employs an electric field for acceleration and during this time, the time taken for the ions to reach the detector is measured. Lighter ions will reach the detector first.The diagram above show the mass spectrum of pentan-3-one. Here the commonest fragment oin(tallest peak) is at m/x = 5 in is important to note that this isn’t produced the same ion.

The m/z =5 was produced by [CH3CH2CH2CH2]+ therefore, there is possibility of getting a particular fragment from pentane. The peak with the m/z =29 is produced my the ethyl ion. Referencesmass spectra - fragmentation patterns. (2014). Chemguide.co.uk. Retrieved 19 April 2014, from http://www.chemguide.co.uk/analysis/masspec/fragment.htmlTime-of-Flight Mass Spectrometry. (2014). Jic.ac.uk. Retrieved 19 April 2014, from http://www.jic.ac.uk/services/proteomics/tof.htmScripps Center for Metabolomics and Mass Spectrometry - Mass Spec History. (2014). Masspec.scripps.edu.

Retrieved 19 April 2014, fromhttp://masspec.scripps.edu/mshistory/whatisms_details.phpMass Spectrometry. (2014). Www2.chemistry.msu.edu. Retrieved 19 April 2014, from http://www2.chemistry.msu.edu/faculty/reusch/virttxtjml/spectrpy/massspec/masspec1.htmUntitled Document. (2014). Astbury.leeds.ac.uk. Retrieved 19 April 2014, from http://www.astbury.leeds.ac.uk/facil/MStut/mstutorial.htm