Tuesday, 4 June 2013

Determination of Relative Atomic Masses of isotopes by Mass Spectrometry

Mass Spectrometer:-
 it is am instrument which is used to determine the exact masses of different isotopes of an element.
How to Measure the masses with Spectrometer:-
     Mass spectrometry works by ionizing chemical compounds to generate charged molecules or molecule fragments and measuring their mass-to-charge ratios.In a typical MS procedure a sample, which may be solid, liquid, or gas, is ionized. The ions are separated according to their mass-to-charge ratio.The ions are detected by a mechanism capable of detecting charged particles. The signal is processed into the spectra (singular spectrum) of the relative abundance of ions as a function of the mass-to-charge ratio. The atoms or molecules can be identified by correlating known masses by the identified masses or through a characteristic fragmentation pattern.
A mass spectrometer consists of three components: ion source, mass analyzer, and detector.The ionizer converts some portion of the sample into ions. There is a wide variety of ionization techniques, depending on the phase (solid, liquid, gas) of the sample, and the efficiency of various ionization mechanisms for the target species in question. An extraction system which removes ions from the sample and gives them a trajectory which allows the mass analyser to sorts the ions by mass-to-charge. The detector, which measures the value of an indicator quantity and thus provides data for calculating the abundances of each ion present. Some detectors also give spatial information, e.g. a multichannel plate.
Mass spectrometry has both qualitative and quantitative uses. These include identifying unknown compounds, determining the isotopic composition of elements in a molecule, and determining the structure of a compound by observing its fragmentation. Other uses include quantifying the amount of a compound in a sample or studying the fundamentals of gas phase ion chemistry (the chemistry of ions and neutrals in a vacuum). MS is now in very common use in analytical laboratories that study physical, chemical, or biological properties of a great variety of compounds.

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