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mass spectrOSCOPY
Mass spectrometry involves ionizing molecule samples and then measuring their mass-to-charge ratios. The samples are bombarded with electrons to produce molecular ions, which then fragment into product ions. These ions are separated based on their mass-to-charge ratios and detected, producing a mass spectrum that shows the abundances of each ion. This spectrum provides structural information about the precursor molecule and can be used to identify unknown compounds. Mass spectrometry is widely applied across many scientific fields including pharmaceutical analysis, environmental testing, and forensics.
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More from MAHAJAN DHANRAJ,R C PATEL INSTITUTE OF PHARMACEUTICAL EDUCATION AND RESEARCH, SHIRPUR
mass spectrOSCOPY
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- 2. Mass spectrometer ismeasurement of atomic mass of molecules and atoms and detection of then on the basis of mass to charge ratio. Mass number(A) – it is total number of protons and neutrons in atom. it is different for different atoms and molecules. E.g.. carbon atom have 6 proton +6 neutrons in nucleus hence its mass number is 12
- 3. What is itmass spectrometery? It is instrumental technique in which sample is converted to positive charged ions by electron bombardment and the particles are separated according to their mass, finally they are detected by detector What is mass spectrum? It is plot of relative abundance against ratio of mass/charge(m/e)
- 6. The first stepin the mass spectrometric analysis of compounds is the production of gas phase ions of the compound, basically by electron ionization. This molecular ion undergoes fragmentation. Each primary product ion derived from the molecular ion, in turn, undergoes fragmentation, and so on. The ions are separated in the mass spectrometer according to their mass-to-charge ratio, and are detected in proportion to their abundance. A mass spectrum of the molecule is thus produced. It displays the result in the form of a plot of ion abundance versus mass-to-charge ratio. Ions provide information concerning the nature and the structure of their precursor molecule.
- 7. In the spectrumof a pure compound, the molecular ion, if present, appears at the highest value of m/z (followed by ions containing heavier isotopes) and gives the molecular mass of the compound. Components The instrument consists of three major components: Ion Source: For producing gaseous ions from the substance being studied. Analyzer: For resolving the ions into their characteristics mass components according to their mass-to-charge ratio. Detector System: For detecting the ions and recording the relative abundance of each of the resolved ionic species.
- 9. Stage 1 Ionisation- ElectroIonisation is the most common type of ionisation. The sample is bombarded by electrons which come from a heated filament. The electrons run in a stream between the cathode and anode. When the sample passes through the electron stream, the high energy electrons in the stream knock electrons out of the sample to form ions. Stage 2 Acceleration Acceleration is a simple step where the ions are placed between a set of charges parallel plates. The ions will then be repelled by one plate and attracted to the other. There is a slit cut in the plate which the ions are attracted to. the force of attraction and repulsion forces the ions through the slit at an accelerated rate. The speed of acceleration can be adjusted by changing the charge on the plates.
- 11. Stage 3 Deflection ionsare deflected by the magnetic field surrounding the instrument. The amount of deflection depends on the mass and charge of the ions. The heavier ions and ions with a positive charge of 2 or more, are deflected the least (Ion stream C) The lightest ions and ions with 1 positive charge are deflected the most (Ion Stream A) The ions at the correct mass and charge travel to the detector. (Ion Stream B) The mass to charge ratio (m/z) is determined from the ion that hits the detector.
- 13. Step 4 Detection Whenthe ion stream reached the detector the hit a wire. On hitting the wire they become neutralised by an electron jumping from the metal wire to the ion. The amplifier picks up on this current being created between the wire and the ion and amplifies the signal being detected. The computer picks up on this and converts it to mass/charge ratio and a spectrum is produced.
- 21. Applications of MassSpectrometry Mass Spectrometry as a technique can be coupled with other techniques such as HPLC and GC. As it is used in the identification of compounds it is used in all areas of science. Some of its uses are : Trace Gas Analysis, Pharmaceutical Industry, Space Exploration, Forensic Toxicology, Archaeological Dating.