ICP and AA
Purpose:
The purpose of this lab was to be able to learn how to us the Varian Spec 20 Atomic
Absorption Spectrophotometer and the Varian ICP. The objective was to investigate operation
of the AA and ICP by creating calibration curves using standards of copper and zinc. Then it was
to create a new calibration curve and run samples that were taken from the water fountain outside
the laboratory and water from the sink within the laboratory.
Introduction:
Inductively Coupled Plasma (ICP) is an emissions spectrophotometric technique. Each
element emits energy at specific wavelengths particular to its chemical character, but each
element emits energy at multiple wavelengths. So the ICP is most common to select a single
wavelength for a given element. It is similar to the technique of the AA but instead is with
plasma three to four times the temperature of the typical AA flame. The intensity of the energy
emitted at the chosen wavelength is proportional to the amount of that element in the sample.
Atomic Absorption Spectroscopy (AA) uses the absorption of light to measure the
concentration of gas-phase atoms. Since samples are usually liquids or solids, the analyte atoms
or ions must be vaporized in a flame or graphite furnace. The analyte concentration is determined
form the amount of absorption. AA is used primarily for metals analysis. Our AA flame uses
air/acetylene and the detection levels are typically in the ppm range.
Procedure:
ICP
 Prepare a blank, five standards and all samples before starting up the instrument.
o Standard 1: Prepare 10 ppm of Copper and 10 ppm of zinc and put in one 100 mL
volumetric flask. Dilute to mark with distilled water.
o Do the same for 20 ppm, 30 ppm, 40 ppm, and 50 ppm
o Turn on the cooling system located behind the ICP and allow to run for 15
minutes before use.
 Turn on the exhaust vent (right, black button).
 Turn on the Argon gas in all three places
 After 15 minutes turn on the ICP computer screen.
 Pull tubing so the blue and white tabs are in place as shown in the picture below.
 Tighten the tubing by locking the rollers in place by placing the three poles at the bottom
up
 Open the ICP expert program on the computer located to the right of the machine.
 Select worksheet
o Select new
o Name new file and select save
 Select the edit method tab
 Click and drag elements to the box below (Copper and Zinc)
 Select the standards tab
 Enter the standard concentrations
 Exit screen
 Select ‘yes’ to save
 Click plasma on
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AA:
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Once flame is lit allow it to heat up for 15 minutes before running samples.
o Put tubing in distilled water (blank) while waiting
Select the sequence editor
o Select number of samples
o Check the ‘Begin with calibration’ box
o ‘Include blank in calibration’ box is checked
Select the analysis tab
o Ensure all standards and sample to be run are highlighted yellow. If not yellow,
click on the tube number button to highlight.
o Click the green arrow to begin running samples
Follow the on screen instructions
o Be sure to rinse tubing with distilled water between each sample
Prepare a blank, five standards and all samples before starting up instrument.
o Standard 1: Prepare 10 ppm of Copper and put in a 100 mL volumetric flask.
Dilute to mark with distilled water.
o Do the same for 20 ppm, 30 ppm, 40 ppm, and 50 ppm of Copper and Zinc
Turn on power switch on the front of the instrument.
Turn on two gases, acetylene and compressed air, in the storage room and then on the
bench top.
Turn on the exhaust fan on the wall column near the AA and is labeled EXH. FAN 4.
Install the lamps.
o Open the AA lid and check to make sure all lamps are pushed in the whole way
Open WinLab32 software on Desktop.
Click “Lamps” icon in top bar menu.
Turn lamp(s) on by highlighting the appropriate row and clicking the “On/Off” button
(button will turn green).
Wait 10 minutes for the lamp(s) to warm up before starting analysis.
Click “Wrkspc” icon in the top menu bar.
Select file “Man.flm” to initialize a manual analysis.
From the File drop down menu, select “New” then “Method”.
Select element from drop down menu.
o Check “Recommended values” and click “Ok”.
Select the “Spectrometer” tab in the Method Editor and check to see if the right element
is listed.
Select the “Standard Con.” tab.
o Enter blank and standards information
Click the “Equation and Units” side tab.
o Select equation for calibration curve (linear, calculated intercept)
o Plug in concentration units
Click “SamInfo” icon in top menu bar
o Enter relevant information into the Sample Information Editor window for each
sample
o Close window
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Select the Flame Control Window
Check the “Safety Interlocks” box.
o Green with a check mark indicates flame is ready
o Red box with an X indicates a problem. Click on the box to see what the problem
is.
Click “On” to light the flame. This may take a couple tries.
Select Manual Analysis Control window.
Place probe in blank solution and click “Analyze Blank”.
Place probe in first standard and click “Analyze Standard”. Repeat for all standards.
Place probe in sample and click “Analyze Sample”. Repeat for all samples.
When finished, aspirate deionized water for several minutes to rinse system.
Click “Lamps” icon in top menu bar and turn off all lamps by clicking “On/Off”.
Select Flame Control window and switch the flame off.
Turn off compressed air and acetylene valves on benchtop and then in the storage room.
Select Flame Control window and click “Bleed Gases”.
Once complete, return to gas room and check outlet pressure on acetylene regulator.
o If below 15 psi, turn off both gas valves in the room and then on the bench top.
o If above 15 psi, bleed gases again and check after.
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Day 1:
1. Investigate operation of the AA and ICP by creating calibration curves using standards of copper
and zinc.
Day 2:
1. Create a new calibration curve and then run samples.
2. Repeat Step 1 for the second metal
3. Run calibration and samples on ICP
Data:
All printed data can be found in instrumental notebook.
Calibration Curves for ICP:
Intensity (c/s)
Copper Calibration Curve
450000
400000
350000
300000
250000
200000
150000
100000
50000
0
y = 5985.8x + 351.39
R² = 1
0
20
40
Concentration (ppm)
60
80
Zinc Calibration Curve
Intensity (c/s)
120000
y = 2009.7x + 14.216
R² = 1
100000
80000
60000
40000
20000
0
0
10
20
30
40
50
60
Concentration (ppm)
Samples:
Sample
Tap Water
Water Fountain
Copper Concentration
0.045 ppm
0.040 ppm
Zinc Concentration
0.133 ppm
0.103 ppm
Calculations:
y= 5985x + 351.3
622.31= 5985x + 351.3
y=0.0453 ppm
y=2009x + 14.21
281.58=2009x + 14.21
y= 0.133 ppm
y= 5985x + 351.3
590.67= 5985x + 351.3
y=0.040 ppm
y=2009x + 14.21
220.48=2009x + 14.21
y= 0.103 ppm
Conclusions:
The AA and ICP were, overall, easy instruments to learn how to operate. We found out
after using the AA that the read out was not giving us reliable absorbance and concentration
values. Therefore, calibration curves could not be constructed for the samples ran on the AA.
The SOP was also changed for the AA because the instruction to bleed out the gases was not in
the correct order. The ICP, on the other hand, produced reliable data that was easy to understand
and therefore a calibration curve could be made with this data. When using the ICP, however, we
did have some troubles in the beginning because the SOP was difficult to understand. Therefore,
we ran into troubles when we did not lock in the pressure knobs and the nebulizer began to fill
up with water. The problem was resolved quickly, however, and we learned from our mistake.
From the calibration curve that we made, the concentration of the samples we took from the
water fountain and the lab sink could be determined. Within the water samples we collected, the
zinc concentrations were always higher than the copper concentrations. There were slight
differences between the unknown samples that we collected, but nothing that was drastic.
Unfortunately, since we were not able to make a calibration curve with the AA, the data between
the two instruments could not be analyzed.