Premid Chroma

Question 1

is an analytical technique that measures the concentrations of elements. It makes use of the absorption of light by these elements in order to measure their concentration.

Answer 1

ATOMIC ABSORPTION SPECTROSCOPY
(AAS)

Question 2

quantifies the absorption of ground state atoms in the gaseous state.

-The atoms absorb ultraviolet or visible light and make transitions to higher electronic energy levels. The analyte concentration is determined from the amount of absorption.

Answer 2

Atomic absorption spectroscopy

Question 3

are usually determined from a working curve after calibrating the instrument with standards of known concentration.

Answer 3

Concentration measurements

Question 4

is a very common technique for detecting metals and metalloids in environmental samples.

Answer 4

Atomic absorption

Question 5

The Atomic Absorption Spectrometer Atomic absorption spectrometers have 4 principal components

Answer 5

1- A light source (usually a hollow cathode lamp)
2- An atom cell (atomizer)
3-A monochromator
4- A detector, and read out device.

Question 6

Schematic Diagram of an Atomic Absorption Spectrometer

Answer 6

Light source
Atomizer Baliktan na cone
Monochromator Pyramid
Detector and readout unut Oblong

Question 7

is usually a hollow cathode lamp of the element that is being measured . It contains a ______________made of the element to be determined. These are sealed in a glass tube filled with an __________. Each element has its own unique lamp which must be used for that analysis.

Answer 7

light source

tungsten anode and a hollow cylindrical cathode

inert gas (neon or argon)

Question 8

Elements to be analyzed needs to be in

Answer 8

atomic sate

Question 9

is separation of particles into individual molecules and breaking molecules into atoms .This is done by exposing the analyte to high temperatures in a flame or graphite furnace. The role of the atom cell is to primarily dissolvate a liquid sample and then the solid particles are vaporized into their free gaseous ground state form In this form atoms will be available to absorb radiation emitted from the light source and thus generate a measurable signal proportional to concentration.

Answer 9

Atomization

Question 10

There are two types of atomization:

Answer 10

Flame and Graphite furnace atomization.

Question 11

Types of Flames Used in Atomic Spectroscopy Fuel and Oxidant :
Gas/Air
H2/Air
H2/02
Gas/O2
*C2H2/Air
*C2H2/N2O
*C2H2/02

Answer 11

Temperature degree celsius
1700-1900
2000-2100
2550-2700
2700-2800

2100-2400
2600-2800
3050-3150

Question 12

The Atomic Absorption Spectrometer Sample Introduction System:
Parts

Answer 12

Nebuliser
Capillary
Solution

Question 13

It is the fine mist of droplets is mixed with fuel________, and oxidant______
and burned. The flame temperature is important because it influences the distribution of atoms. It can be manipulated by oxidant and fuel ratio.

Answer 13

Atomic Absorption Spectrometer
fuel (acetylene)
oxidant (nitrous oxide)

Question 14

Atomic emission uses

Answer 14

Excited atoms

Question 15

Atomic absorption uses

Answer 15

Ground state atoms

Question 16

The concentration of the analyte element is considered to be proportional to the ground state atom population in the flame, any factor that affects the ground state atom population can be classified as an___________

Factors that may affect the ability of the instrument to read this parameter can also be classified as an_________.

Answer 16

Interference

Question 17

The different interferences that are encountered in atomic absorption spectroscopy are:

Answer 17

Absorption of Source Radiation

Ionization Interference

Self Absorption

Transport Interference

Back ground Absorption of Source Radiation

Question 18

:Element other than the one of interest may absorb the wavelength being used

Answer 18

Absorption of Source Radiation

Question 19

: the formation of ions rather than atoms causes lower absorption of radiation .This problem is adding ionization suppressors.
atoms overcome by wings

Answer 19

Ionization Interference

Question 20

: the atoms of the same kind that are absorbing radiation will absorb more at the center of the line than at the ,and thus resulting in the change of shape of the line as well as its intensity.

Answer 20

Self Absorption

Question 21

: This is caused by the presence of a particle from incomplete atomization .This problem is overcome by increasing the flame temperature.

Answer 21

Back ground Absorption of Source Radiation

Question 22

: Rate of aspiration, nebulization, or transport of the sample (eg viscosity, surface tension, vapor , and density).

Answer 22

Transport Interference

Question 23

AAS APPLICATIONS
The are many applications for atomic absorption:

Answer 23

Clinical Analysis
Environmental Anlaysis
Pharmaceuticals
Industry

Question 24

: Analyzing metals in biological fluids such as blood and urine.

Answer 24

• Clinical analysis

Question 25

: Monitoring our environment - eg finding out the levels of various elements in rivers, seawater, drinking water, air, and petrol

Answer 25

• Environmental analysis

Question 26

In some pharmaceutical manufacturing processes, minute quantities of a catalyst 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.

Answer 26

Pharmaceuticals

Question 27

: Many raw materials are examined and AAS is widely used to check that the major elements are present and that toxic impurities are lower than specified-e g in concrete, where calcium is a major constituent, the lead level should be low because it is toxic.

Answer 27

Industry