AAS (1 Viewer)

[Atef]

Can someone summarise the whole process for me?

 

[sharoooooo]

Basically, AAS is a highly sensitive and specific process to determine the concentration of cations in a sample.
This method is best used for when the cations in the substance is known; otherwise, it is rather time consuming.

How it works?
The sample is aspirated into the nebuliser (into the flame) where the cations will be ionised into atoms.
A hollow cathode lamp with a corresponding wavelength to the cation being tested is emitted into that flame.
On the other receiving side of the flame, there is a monochromator which splits the wavelengths of light.
The detector following the monochromator detects the initial wavelength emitted by the cathode lamp and analyses the absorbency level (the atomised cations in the flame absorb some of the intial beam).
Hence, using the info provided by the detector of the absorbancy level, it is compared to a calibrated curve (a curve of absorbance VS. concentration, which was created using a series of standard solutions (which are samples with known concs)) Using this curve, we can determine the conc of the cation present in the sample by comparing the absorbance.

The image below supports this

http://www.hsc.csu.edu.au/chemistry/core/monitoring/chem943/aasequipment.gif

Hope this helps
I love chemistry

 

[Mr_Kap]

HSC 2004:

What is the purpose of the light source and the flame in AAS? 2 Marks


For the flame, success one wrote: The flame provides the heat needed to vaporise the sample being analysed.

However, the notes from the marking centre say: "Poorer responses relating to the purpose of the flame used words like "add heat", "burns" or "ionises".

So what would you write then?

 

[Mr_Kap]

BUMP!

 

[Silly Sausage]

HSC 2004:

What is the purpose of the light source and the flame in AAS? 2 Marks


For the flame, success one wrote: The flame provides the heat needed to vaporise the sample being analysed.

However, the notes from the marking centre say: "Poorer responses relating to the purpose of the flame used words like "add heat", "burns" or "ionises".

So what would you write then?

Vaporises is correct, add heat and burns is too informal and doesn't say what happens to the sample. Ionises is completely wrong. (Since the flame is to turn the ions into atoms). Another word is atomises.

 

[DepressedPenguino]

HSC 2004:

What is the purpose of the light source and the flame in AAS? 2 Marks


For the flame, success one wrote: The flame provides the heat needed to vaporise the sample being analysed.

However, the notes from the marking centre say: "Poorer responses relating to the purpose of the flame used words like "add heat", "burns" or "ionises".

So what would you write then?

Another function of the flame is to increase the total absorbance of the light of specific wavelength by the atomised sample

 

[BlueGas]

Note sure if you still need this Kap but the purpose of the flame is to atomise the substance (Taken from a multiple choice HSC question).