By: Kelly, Jeff, Hieu

What is AAS? Principle of Atomic Absorption Development of atomic absorption. The use of FAAS. Instrumentation of FAAS. How does it function? Interferences in FAAS. Advantages and disadvantages. Applications of FAAS. How reliable is FAAS?

Atomic absorption measure the amount of energy is absorbed by the sample. Through this we could determine the type of metal in the sample.

Every atom of an element has its unique electron's configuration therefore the pattern of wavelengths at which the incoming energy will be absorbed is unique to that atom.

Taking advantage of this principle, allow us to precisely identify the examined sample as surely as a fingerprint identifies a person.

The phenomenon of atomic absorption was first observed in 1802 with the discovery of Fraunhofer lines in the sun’s spectrum.

Developed during the 1950s by a group of Australian chemists lead by Alan Walsh.

Statistical data◦ By 1969 there were 10,000 AAS machine world

wide.◦ By 1977 there were 40,000 AAS machine world

wide.

Determine what type of metallic elements that exist in a compound.

Determine the concentration of the known element present in the sample solution.

Allows measurement of extremely small amounts of elements.

One of the most significant achievements in chemical analysis last century.

Dissolved compound– the liquid solvent is evaporated, while the dry sample remains

Vaporization – the solid sample is vaporized into a gas

Volatilization – the compounds making up the sample are broken into free atoms.

Mass the sample and dissolve in the suitable solvent.

When making a reference solution, the sample solution should closely match the reference solution.

Reference solution is used to calibrate the machine◦ The reference solution and the sample solution

should be prepared the same way. They both should contain the same solvent and same compound.

Light Source

Detector

Sample Compartment

The light source is a lamp filled with neon or argon gas and the cathode is composed of the element that is being measured.

Each element required a different lamp. The use of special light sources and specific

wavelength selection allows the quantitative determination of individual components of a multi-elements mixture.

There are two types of atomizer: Flame and Flameless atomizer.◦ Electrothermal Atomizer◦Flame Atomizer

The use of this device allows:◦ Vaporize solution ◦ Separate the atoms into individual elements;

more specifically to isolate the metal.

Electrical heating of sample container for vaporization and atomization of the sample.◦ Flameless Atomic Absorption

Graphite furnace is used. Atomizer cell is a graphite tube or cup

◦ The tube is heated by passing a current

The machine is calibrated by running several known concentration of the reference solution through the machine

Calibration curve will be produced, base on this graph we could compare to the concentration of our unknown and identify our unknown element.

Anything that affects the favorable result is considered interference.◦ Spectral Interference: background absorption due

to radiation overlapping that of the light source. The interference radiation may be an emission line of another element or compound, or general background radiation from solvent, or analytical sample.

◦ Matrix interferences due to differences between surface tension and viscosity of the test solutions and standards.

◦ Ionization of the analytical element that reduces the signal.

Advantages◦ Higher Sensitivity◦ Lower detection limits◦ Smaller simple size◦ Direct analysis of solid◦ Simple to operate and

reliable.

Disadvantages◦ Matrix interference◦ Formation and

dissociation of molecular species

◦ Sample furnace interactions

◦ Less precise then flame AAS

Most accurate at identifying single elements as opposed to multiple simultaneous elements.

Clinical Analysis◦ Analyzing metallic element in biological fluid such

as blood. Environmental Analysis

◦ Determining various metals in seawater, drinking water, air and etc.

Pharmaceutical ◦ Measure the amount of catalyst (metal) in

medicinal products. Industry-Automobiles

◦ Determine amount of metals in various products like car oil and other substance.

For 200 years controversy has surrounded Napoleon's death. 

In 1995, the FBI used Graphite Furnace Atomic Absorption Spectroscopy to investigate the theory that Napoleon Bonaparte was murdered via arsenic poisoning, by examining preserved samples of hair from Napoleon himself.  Results showed high concentrations of arsenic, thus supporting the theory that Napoleon was murdered. 

Only until a thorough investigation in 2007 came to the conclusion that he died from stomach cancer, was the controversy finally laid to rest.

"Atomicabsorption Spectrometry." <http://www.chemsoc.org/pdf/LearnNet/rsc/AA_txt.pdf>.

"Napoleon Bonaparte Died of Arsenic Poisoning: Evidence Published in The American Journal of Forensic Medicine and Pathology". Business Wire. Feb 10, 2000. FindArticles.com. 22 Jan. 2008. http://findarticles.com/p/articles/mi_m0EIN/is_2000_Feb_10/ai_59316816

"Biographical Memoirs." Alan Walsh . Australian Academy of Science. 22 Jan 2008 <http://www.science.org.au/academy/memoirs/walsh2.htm#16>.

Briant, C. L.. Impurities in Engineering Materials: Impact, Reliability, and Control . CRC Press, 1999.

Tissue, Brian. Atomic-Absorption Spectroscopy. 8/21/96. 22 Jan 2008 <http://elchem.kaist.ac.kr/vt/chem-ed/spec/atomic/aa.htm>.