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Chemistry Chromatography in a nutshell

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  • 18-06-2007 3:46pm
    #1
    madgal
    Closed Accounts Posts: 158 ✭✭


    (still getting pm's for this so just gonna post it up)

    Atomic Absorption Spectrometer:-
    Principal: Atoms can absorb light + the wavelength of the light absorbed is characteristic of the element.
    How it functions: The amount of light absorbed by the falme which contains the sample indicates the concentration of the metal.
    Uses:
    1. Analysis of water for lead and Mecury, Cadmium *heavy metals*


    Mass Spectrometer:-
    Principal: Ions of seperated according to their masses in an electromagnetic field
    Process: Vaporisation, Ionisation, Acceleration, Seperation, Detection (VIAGRA) you will need to look this up further in your book and know 1-2 lines about each.
    Uses:
    1. Identify presence of Isotopes
    2. Measure their relative abundance
    3. Measure relative atomic & Molecular Masses.


    Gas Chromatography:-
    Principal: A mobile phase carries the components of a mixtue at different rates through a stationary phase.

    Process:
    a) Sample injected into hot column
    b) Sample vaporised
    c) Brought through column by carrier gas
    d) Seperated as they flow through column
    e) Detected on a Gas chromatogram.

    Uses:
    1. Level of alcohol in blood and urine samples
    2. Drug test samples from athletes.


    High performance liquid chromatography
    Principal: (Same as Gas chromatography "A mobile phase carries the ...')
    Process:
    a) Liquid carries the sample through a column using a pump
    Column not as long as in the gas chromatograph, and not as high temp

    Uses:
    1. Test for growth proviotors in food
    2. Additives in food.


    Infrared Spectrometer:
    Principal: Organice compounds absorb IR light by vibrations of their bonds
    Process:
    IR spectrum serves as a fingerprint
    Uses: Identify plastics or illegal drugs


    Ultraviolet spectrometer:
    Principal: Organic compounds absorb UV light characteristic of the functional group
    Process:
    UV spectrum serves as a fingerprint
    Uses: To measure concentration of organics.


Comments

  • Options
    #2
    JC 2K3
    Closed Accounts Posts: 7,794 ✭✭✭JC 2K3


    You only need to learn how to do one of them and a very basic knowledge of what the others involve AFAIK.

    Paper Chromotography ftw.


  • Options
    #3
    madgal
    Closed Accounts Posts: 158 ✭✭madgal


    JC 2K3 wrote:
    You only need to learn how to do one of them and a very basic knowledge of what the others involve AFAIK.

    Paper Chromotography ftw.

    [refers to 2002 paper Q7]
    7. Mass spectrometry and gas chromatography are widely used instrumental techniques in chemistry.
    (a) Give one application of each of these techniques.
    (b) What are the main principles on which each of these techniques is based?
    (c) What are the fundamental processes that occur in a mass spectrometer?
    (d) HPLC is another chromatographic technique.
    What do the letters HPLC stand for? State one application of this technique.


    You were saying?


  • Options
    #4
    JC 2K3
    Closed Accounts Posts: 7,794 ✭✭✭JC 2K3


    Firstly, in 2002 there were complaints about that question.

    Secondly, I see nothing there that requires an in depth knowledge of a chromatographic technique. The principle of GC, HPLC and PC are all the same. The Mass Spectrometer is in a different area of the course also, so you need to kow that by default.


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