QUANTITATIVE
ANALYSIS
Determining amount of ions present in
samples
Atomic Absorption Spectroscopy
Cathode lamp
AAS
Cathode lamp is specific for the element to be measured
• Eg. To test lead in water sample use a lead cathode; the lamp will
generate wavelengths that are specific to lead
•
• The greater the concentration of ions in the sample, the greater the
amount of light absorbed (less transmittance)
Absorbance
Transmittance
AAS
Standard Solutions
• Prepare a series of dilutions of a standard solution (with known
concentration) containing the metal to be analysed
• Measure and record the absorbance for at least 3 different
concentrations
• construct a calibration graph
• Next, measure the absorbance of the sample solution (unknown
concentration)
• Use the calibration graph to interpolate its concentration value
Calibration graph
• A control blank (containing only water) is used; zero
concentration = zero absorbance