ATOMIC ABSORPTION SPECTROMETRY Flashcards
Is AAS a spectroscopy, spectrometry, or spectrophotometry
spectrometry
list on advantage and one limitation of AAS
advantage: capable of detecting ppm or ppb
disadvantage: can only detect metal ions in liquid state
list the 7 features of an AAS setup
- hollow cathode lamp
- flame
- nebuliser
- test solution
5.monochromator - detector
- data processor
what is the function of the cathode lamp
it emits light at wavelengths that corresponds to the absorption lines of a specific element
what is the function of the nebuliser
breaks the liquid sample into fine mist –> efficient transport of the sample to the flame
what is the function of the carrier gases
- transport the sample to the flame
- provide oxygen and fuel to the flame
identify four things that happen to the sample in the flame
1) solvent evaporates leaving small tiny solid particles
2) the solid particles are vaporised into a gaseous state.
3) heat further breaks down molecule compounds into free atoms (atomisation)
4) the free atoms absorb light from the HCL at their characteristic wavelengths.
function of the monochromator
- absorbs the remaining light emitted by the hcl that the molecule doesn’t absorb.
- The monochromator filters out all unwanted wavelengths that were not absorbed by the sample.
function of the detector
measures the intensity of the remaining light after it passes through the sample.
it compares the intensity of the final light and the initial light emitted by the hcl
function of data processor
identifies whether the intensity before flame is different to intensity after flame and calculates absorbance
is AAS destructive or non-destructive analytical technique
destructive because any sample broken down during atomisation cannot be recovered post-analysis
list four industries that use AAS
- agriculture
- pharmaceutical
- manufacturing
- mining
how and what ions is AAS used in agriculture
calcium, iron, zinc
–> determines composition of food products
–> detects toxins, microbial infection
how and what ions is AAS used in pharmaceutical
iron, copper, zinc
–> determine conc. of metal containing drugs
how and what ions is AAS used in manufacturing
metals
–> detects the metals in the sample of ground before building
how and what ions is AAS used in mining
metals
–> detects the metals in the sample of ground before mining
what qualitative technique to identify certain metals ions in solutions was used in year 11
Flame test
describe the flame test
- solution heated over a bunsen burner
- electrons absorb heat energy and jump up a valence shell in excited state
- electrons jump back down to their ground state and releases the excess energy in form of light
- each coloured light produced corresponds to a certain element
identify what flame test and AAS identify
flame test: identifies the cations present in metal salt
AAS: determine the concentration pf metal ions in solution
describe a case when flame test would be used rather than AAS
when you do not need to measure the exact concentration of metal ions, just their presence or absence.
