PRINCIPLE Flashcards
Is an analytical technique that measures the concentrations of elements. It makes use of the absorption of light by these element in order to measure their concentration
ATOMIC ABSORPTION SPECTROSCOPY
It quantifies the absorption of ground state in the gaseous state.
ATOMIC ABSORPTION SPECTROSCOPY
The atoms absorb ultraviolet of visible light and make transitions to higher electronic energy levels. The analyte concentration is determined from the amount of absorption.
ATOMIC ABSORPTION SPECTROSCOPY
Is a very common technique for detecting metals and metalloids in environmental samples.
ATOMIC ABSORPTION SPECTROSCOPY
4 principle components of atomic absorption spectrometer
LIGHT SOURCE (USUALLU A HOLLOW CATHODE LAMP)
AN ATOM CELL ( ATOMIZER)
MONOCHROMATOR
DETECTOR, READ OUR DEVICE
It is usually a hollow cathode lamp of the element that is being measured.
LIGHT SOURCE
A light source contains a _____ and a _____ made of the element to be determined.
TUNGSTED ANODE
HOLLOW CYLINDRICAL CATHODE
The light source is sealed in a glass tube filled with an _______.
INERT GAS (NEON OR ARGON)
To be analyzed needs to be in atomic sate.
ELEMENTS
In separation of particles into individual molecules and breaking molecules into atom.
ATOMIZATION
This is done by exposing the analyte to high temperature in a flame or graphite furnace.
ATOMIZATION
This dissolvate a liquid sample and then the solid particles are vaporized into their free gaseous ground state form.
ATOM CELL
Two types of atomization:
FLAME AND GRAPHITE FURNACE ATOMIZATION
Gas/Air
1700-1900
Gas/O2
2700-2800
H2/Air
2000-2100
H2/02
2550-2700
C2H2/Air
2100-2400
C2H2/O2
3050-3150
C2H2/N2O
2600-2800
Factor that affects the ground state atom population can be classified as an _____?
INTERFERENCE
Factors that may affect the ability of the instrument to read this parameter can also be classified as ___?
INTERFERENCE
Element other than the one of interest may absorb the wavelength being used
Absorption of Source Radiaiton
The formation of ions rather than atoms causes lower absorption of radiation. This problem is overcome by adding ionization suppressors.
IONIZATION INTERFERENCE
The atoms ot the same kind are absorbing radiation will absorb more at the center of the line than at the wings, and thus resulting in the change of shape ot the line as well as its density.
SELF ABSORPTION
This is caused by the presence of a particle from incomplete atomization,. This problem id overcome by increasing the flame temperature.
BACK GROUND ABSORPTION OF SOURCE RADIATION
Rate of aspiration, novelization, or transport of the sample (eg. viscosity, surface tension, vapor pressure and density)
TRANSPORT INTERERENCE
5 different interferences that are encountered in atomic absorption spectroscopy:
ABSORPTION OF SOURCE RADIATION
IONIZATION INTERFERENCE
SELF ABSORPTION
BACK GROUP ABSORPTION OF SOURCE RADIATION
TRANSPORT INTERFERENCE
AAS Applications:
CLINICAL ANALYSIS
ENVIRONMENTAL ANALYSIS
PHARMACEUTICALS
INDUSTRY
Analyzing metals in biological fluids such as blood and urine.
CLINICAL ANALYSIS
Monitoring our environment - eg. finding out the levels of various elements in rivers, seawaters, drinking water, air and petrol.
ENVIRONMENTAL ANALYSIS
In some pharmaceutical manufacturing processes, minute quantities of a catalysts used in the process (usually a metal) are sometimes present in the final product. By using AAS the amount of catalyst present can be determined.
PHARMACEUTICALS
Many raw materials are examined and AAS is widely used to check that the major elements ate present and that toxic impurities are lower than specified - eg in concrete, where calcium is a major constituent, the lead level should be low because it is toxic.
INDUSTRY
Uses excited atoms
ATOMIC EMISSION
Uses ground state atoms
ATOMIC ABSORPTION
It is important because it influence the distribution of atoms. It can be manipulated by oxidant and fuel ratio.
FLAME TEMPERATURE
5 interferences that are encountered in atomic absorption spectroscopy are:
ABSORPTION OF SOURCE RADIATION
IONIZATION INTERFERENCE
SELF ABSORPTION
BACK GROUND ABSORBTION OF SOURCE RADIATION
TRANSPORT INTERFERENCE
It is a major constituent in a concrete, the lead level should be low because it is toxic.
CALCIUM