As it was previous underlined the amount of emitted (AES) or absorbed (AAS) radiation depends on the concentration of the analyte in the sample. The case of atomic emission spectrometry is much simpler because of the proportionality between the signal and concentration. The measuring technique is simple: using some standard solutions a calibration curve is plotted. Then, by measuring the signal of the sample the concentration of the analyte can be determined.
In atomic absorption spectrometry the ratio between the signals measured in the presence and in the absence of the sample is called transmittance (T = P/P0). To make the life more difficult than it already is the transmittance is not proportional to the concentration of the analyte in the sample. Anyway there are scientists like Lambert and Beer who always find quantities proportional to the concentration (c). In this case the quantity is the absorbance (A = -lg T), and the Lambert-Beer law is:
A = kc
Just like in the case of atomic emission spectrometry, by plotting the absorbance against concentration for a series of standards the calibration curve is obtained. Then, by measuring the absorbance of the sample the concentration of the analyte can be determined.
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