Spectroscopy and chromatography

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Author:
Anonymous
ID:
264995
Filename:
Spectroscopy and chromatography
Updated:
2014-03-04 05:11:30
Tags:
chemistry
Folders:
Chemistry
Description:
HPLC, GC, UV VIS, AAS
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  1. What substances would HPLC be used for?
    Medium to high molecular mass organic compounds
  2. What substances would GC be used for?
    Low molecular mass organic compunds
  3. What substances would AAS be used for?
    Most metals eg. Cu, Fe, Zn
  4. What substances would UV VIS be used for?
    Low molecular mass organic molecules
  5. What are the advantages and disadvantages of HPLC?
    Advantage: High sensitivity and precision; small sample size; readily automated

    Disadvantages: Moderately expensive instrument; trained technician to operate
  6. What are the advantages and disadvantages of GC?
    Advantage: High sensitivity and precision; small sample size; readily automated

    Disadvantages: Moderately expensive instrument; trained technician to operate
  7. What are the advantages and disadvantages of AAS?
    Advantages: High sensitivity and precision; easily automated

    Disadvantages: Moderately expensive; trained technician needed
  8. What are the advantages and disadvantages of UV VIS?
    Advantages: Relatively simple to operate

    Disadvantages: not suitable for very low concentrations
  9. How does chromatography work?
    Components of a structure is separated based on their adsorption chracteristics

    • In chromatography, there is a stationary phase which is the solid that the components adsorb to and desorb from. This in the column in which the components travel through. 
    • To aid it move through the column, there is a mobile phase, which is what carries and pushes the components along the stationary phase.
  10. How does atomic absorption spectroscopy work?
    • The analyte is vapourised by placing it in a flame and a wavelength specifically able to have enough energy to excite electrons from the lower energy level to the higher energy level is passed through the analyte
    • The analyte absorbs some of the radiation. The light beam is then passed through a monochromator to select the light of chosen wavelength and its intensity is measured by a detector
  11. How does UV VIS work?
    • A specific wavelength that the substance will absorb is used and passed through the analyte and the amount that passes through is measured by a detector
    • When a substance absorbs visible light, it appears coloured. This is the complementary colour
    • Mainly used for determining concentrations

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