Background: Electron of atoms can absorb electromagnetic energy when they wanna become more 'energetic' and release EM when wanna become less energetic. But ever atom, has different electron configurations and shell numbers, so its absorption of EM waves will be very specific to itself, it'll absorb certain wavelengths only and emit same ones only.
Atomic Absorption Spectroscopy:
A metal to be tested is place in the cathode of a lamp, producing electromagnetic waves whose wavelengths are
characteristic of the metal. The solution to be analysed is aspirated (fed) into a flame, making the metal ions in solution turn into atoms. When the light from the lamp reaches the flame, the atoms absorb those EM waves. So when they absorb, the intensity of energy being emitted from those characteristic wavelengths is reduced. The absorbed rays, there is more than one, go into a monochromatic, which then selects only one of the wavelengths. The sample wavelength is collected by a photo-multiplier connected to a computer. You already were supposed to perform this whole procedure on 'standard solutions' containing the metal. Plot the absorption level/intensity against concentration, forming a calibrated curve. You now check against the curve your value of absorption from the sample being tested, and go down on the curve to find concentration. Dada.
The usually perform the procedure five times and gain and average absorption for the metal being tested in solution.
And you definitely need precipiation and flame tests:
http://community.boredofstudies.org/showthread.php?t=270152
