1. Pre-Lab Talk
Thompson Rivers University
Sample Analysis Using Atomic Absorption Spectroscopy (AAS) 1

2. Outline Analysis of Iron by Atomic Absorption Spectroscopy (AAS)
What we want you to learn from this experiment
Lab Introduction
Standard and Sample Preparation
Dilution of the Fe Unknown
Submitting Your Samples to the BC-ILN
Using the Atomic Absorption Spectrophotometer
Treatment of Data & Results

3. Analysis of Iron by AAS
What we want you to learn from this experiment:
The general principles of Atomic Absorption Spectroscopy (AAS) as an analytical technique
Prepare a sample for quantitative analysis
Identify the main parts of the flame AAS and understand their purpose
Explain why the lamp wavelength is set at 372 nm
Determine whether or not a particular element is present in a solution through the presence or absence of a signal from an atomic absorption transition
Continued…

4. Analysis of Iron by AAS
What we want you to learn from this experiment:
Prepare standard solutions containing known amounts of an element using a Mohr pipet and volumetric flasks
Use experimental data to construct a calibration curve, perform dilution calculations, and calculate the amount of an unknown element in a sample
Assess experimental results to determine accuracy and suggest reasons for any discrepancy or experimental error

5. Lab Introduction AAS Theory
AAS is an instrumental method of quantitative and qualitative analysis
Uses an Atomic Absorption Spectrophotometer
Uses the characteristic absorption spectrum associated with each element, such as iron
Identifies elements present in a wide variety of substances, such as a commercially available multivitamin which contains a wide variety of chemical species including minerals considered to be beneficial to human health

6. Lab Introduction AAS Block Diagram Sample
AAS requires an aqueous sample of adequate volume to ensure there will be enough to perform several runs
Manual
The samples can also be ran manually by inserting the aspirator tube directly into the sample by the operator
Auto-Sampler
Computer operated and programmed to run specific samples, loaded in auto- sampler tubes placed into the auto-sampler racks, in a specific order

7. Lab Introduction Theory
During AAS analysis, an aqueous sample is sprayed into a flame which supplies the energy to dissociate a sample into ground state atoms
This is known as Sample Atomization

8. Lab Introduction
Atomic Absorption Spectroscopy

9. Lab Introduction Theory
The absorbance of the sample is directly proportional to the concentration of analyte atoms in the sample

10. Preparation of Unknown
Fe (Multivitamin) Solution
Obtain a multivitamin tablet and record the brand name and mass of iron per tablet
Place the tablet in a 150 mL beaker and add 20 mL of 6.0 M hydrochloric acid (HCl)
Swirl gently and let stand while preparing the standards
To be continued…

11. Preparation of Standards
Fe Standard Solutions
Use five 100 mL volumetric flasks and a Mohr pipet to prepare a series of solutions containing approx. 1, 2, 3, 4 and 5 mL of 500 mg/L calibrating stock solution
Read and record the actual volume used accurately to two decimal places in your data book
Fill each flask to the mark with deionized water
Invert the flask several times to ensure thorough mixing

12. Preparation of Unknown
Fe (Multivitamin) Solution
…Continued from before
Heat the 150 mL beaker on a hotplate in the fumehood, swirling periodically and note observations
Prepare a fluted filter paper and gravity filtration apparatus
Gravity filter the solution into a 100 mL volumetric flask
Rinse and fill to the mark with deionized water

13. Dilution of Fe Solution
Obtain 40 mL of the prepared unknown Fe solution
Use a 25 mL volumetric pipet to dilute exactly mL of unknown Fe solution into a 100 mL volumetric flask
Fill to the mark with deionized water

14. Submitting Your Samples
Prepare your labeled autosampler tubes for submission to the BC-ILN
Your instructor will supply you with autosampler tubes with caps and a rack to put them in for submission
Label the tubes and organized them in the rack provided
3 cm

15. Running Your Samples During your scheduled instrument time…
Go to your computer station get connected to the BC-ILN
Ask your instructor to show you how to operate the Atomic Absorption Spectrophotometer

16. Running Your Samples

17. Treatment of Data Graphing the Results Title Calibration Curve
Figure 2. Calibration Curve for Iron prepared using a Varian AAS model 55B
Title
Calibration Curve
Label Axis with Units
Label Unknown Values

18. Presentation of Results
Data-Book
Page No.
Experiment
Date
Title
Brand Information
Observations
Stock Solution
Neat Tables