Atomic Absorption Spectrometer
Varian SpectrAA Model 220FS
The Instrument
The instrument consists of:
1. A flame
2. Lamps to produce the correct wavelength of
light
3. A detector
4. A system to aspirate solutions into the flame
5. A computer to control the experiment
The Instrument
On the left is the flame (behind
the grid) and the spectrometer.
The two bottles contain water
used for flushing the tubing and
for diluting solutions that are
too concentrated. The round
object is a pump.
On the right is a cabinet
containing the lamps shown on
a later slide.
The flame, like all large burners,
is vented at the top.
The Lamps
From bottom to top,
the lamps are for Mg,
Ca, K, and a
combination of Fe,
Co, Ni, Mn, Cu, and Cr.
Each element uses a
specific wavelength of
light.
The Flame
The flame is with
only water being
aspirated.
The two holes, left
and right, are
where the light
beam enters and
leaves after passing
through the flame.
The dark place at
the top is a stain
from the heat of
the flame.
The Instrument
Current spectrometers use a PC Computer to control the
experment.
There needs to be standards (solutions of known concentration)
to calibrate the instrument.
The experiment must be setup in the program controlling the
experiment with
• Ions to be analyzed
• Concentration of the standards
• Number of points to be measured
• Wavelength of light
• Lamp Position
Measurement - Standards
A set of
standards
ready to be
aspirated into
the flame. This
instrument
automatically
dilutes the
solution.
Aspiration of the Solution Being Measured
A sample of
maple
syrup ready
to be
aspirated
into the
flame.
The PC Screen
The solution
being
measured
has an
absorbance
of 0.068
which
corresponds
to a
concentration
of 10.2 ppm
Colors Produced by Different Ions
The following slides show the colors of different
ions in the flame. The differences in intensity
of the colors is, in part, due to differences in
concentration.
The Calcium Flame
The calcium
flame is
red. This is
intensely
red
because
the calcium
content is
high.
The Copper Flame
The Potassium Flame
The Manganese Flame
The Cobalt Flame
Results
The computer stores the data which can be
printed.
The experiment can be set up to show the
calibration curve and the concentrations on
the screen. To get reliable concentrations, the
program must be told what fitting algorithm
to use. As can be seen on the screen shown
previously, the calibration data are not linear
in that instance.