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Analysing Unknown Substances - Coggle Diagram
Analysing Unknown Substances
Atomic Absorption Spectroscopy
How does it Work?
After dissolving sample in solvent, pass through atomiser to vapourise
Lamp beams specific element. Current passes through it, exciting specific electrons, producing specific desired wavelength
Vaporised sample will absorb light from lamp only for specific element, because they have same energy level. Passes through slit into monochromator, detector analyses intensity of light
Compare intensity measured against a calibration curve of concentration against absorbance to determine concentration of unknown substance
In prep for the calibration curve, make sure to measure intensities of known concentrations beforehand
What does it determine about inorganic substances?
by testing intensities against certain elements, you can determine a substances composition by its concentration
What are the benefits and limitations of its use?
determine unknown concentrations of substances
only requires a small amount of sample to determine intesnity
high accuracy; to parts per billion (ppb)
Highly expensive apparatus necessary for procedure
Requires good background knowledge/calibration curve
easy to operate
less versatile; has to be vapourised so solids can't be done
Examples of its application in industry
detection of toxic metals in pathology
monitoring metal pollutants in soil or water
detecting quantity and presence of precious metals for mining
detect accumulation of aluminum/mercury/lead/zinc/etc. in human body
UV-Visible Spectrophotometry
How does it work?
there is direct correlation between amount of light absorbed and concentration of a substance
known as Beer-Lambert Law
lamp directs light into cuvette of substance
sample absorbs particular wavelenghts
unabsorbed passes through, diffracted onto detector
view spectrograph in 2 seconds, wavelength against absorbance.
sub in absorbance to find concentration
What does it determine about inorganic substances?
concentrations of elements that make it up
Benefits and Limitations of its Use
very fast; graphs in 2 seconds
use very small volumes
liquid form
Industrial Applications
FDA sets requirements on caffeine in drinks.
determine concentrations for quality control
