1. By
Maryum Atique
M.Phill chemistry
University of Agriculture

2. 

The term heavy metal refers to any metallic
chemical element that has a relatively high
density and is toxic or poisonous at low
concentrations. They cannot be degraded or
destroyed.
Examples of heavy metals include mercury
(Hg), cadmium (Cd), arsenic (As), chromium
(Cr), thallium (Tl), and lead (Pb).

3. Most air toxics originate from anthropogenic
sources like
 Mobile sources (e.g., cars, trucks, buses)
 Stationary sources
(e.g., factories, refineries, power plants), and
even released from
 Natural sources such as volcanic eruptions
and forest fires.

4. 


Heavy metals presents in trace concentration play
a major role in metabolism. Some metals, such as
iron, chromium and copper, are needed in small
quantities to keep people and animals healthy.
Further their increased in concentration may
have several toxicological effects on human
beings.
Heavy metal exposure causes serious health
effects, including reduced growth and
development, cancer, nervous system damage,
and in extreme cases, death.

5.  Sample
collection
 Sample preparation
 Instrumental analysis

6. Collection of samples from different regions.
 Sample is collected from Rural and Urban
areas.
 Industrial and residential areas.
 Collection in polyethylene bags to minimize
sample loss.
 Protected from light and kept at low
temperature.


7. 



Air Filter Samples
Sampling pumps
Stopwatch and bubble tube or meter for
pump calibration.
De ionized water.

8. Methods Of Preparation
1.
2.
Microwave Extraction
Hot Acid Extraction

9.  Cutting
of filter paper
 Extraction in acids
 HCl 8 %, HNO3 3 %
 Calibration of Microwave oven
 Use of digestion vessel

10.  Take
filter strips in a beaker
 Refluxing on hot plate
 Use 10 ml of 8 % HCl and 3 % of HNO3
solution
 Filtration of digestate

11.  Technologies
 Atomic
for metal analysis
absorption spectroscopy
 Flame atomic absorption
spectroscopy

12.  For
absorption, a hollow cathode lamp or
an electrodeless discharge lamp (EDL) is
used as the light source.
 A double beam spectrophotometer is
normally used where the lamp radiation
alternately passes through and around a
flame into which the sample is being
aspirated. The sample is atomized and the
metal or metalloid atoms absorb light.

13.  This
absorption is proportional to the
concentration of the element present in
the sample solution. A monochromator
isolates the characteristic radiation of the
element being analyzed.
 A photosensitive device then measures
the intensity of the transmitted radiation
from the two light paths to determine the
amount of absorbance occurring in the
flame.

14. For emission, a light source is not used. The sample is
introduced into the flame, atomized and excited, and
then the light emission from excitation is isolated and
measured. The intensity of the light emitted is
proportional to the concentration of the element
present.
 flames used are:
 a) Air/Acetylene mixture (Air/C2H2)
 b) Nitrous oxide/Acetylene mixture (N2O/C2H2)
 c) Air/Hydrogen mixture (Air/H2)
 The use of a specific flame is dependent on the
respective element's analytical stability

15. Analytical technique differ in terms of
1. Sensitivity
2. Cost of analysis
3. Requirements for sample preparation
AAS
• Sensitivity
• Selectivity
• Accuracy
• Reproducibility
• Low cost

16. Atomic absorption spectroscopy
Flame atomic absorption spectroscopy
Graphite furnace atomic absorption
spectroscopy
 Inductively coupled plasma emission
spectroscopy
 Neutron Activation analysis
 Electron microscopy


17. Exposures to airborne metals are known to
cause physiological responses in organisms
and health effects in humans. Hence
determination of metals is important from a
toxicological perspective.
 Significant positive correlation among metals
lead and copper suggests that they originate
mostly from a common source.
 Air samples of urban and industrial areas
showed higher concentrations than residential
(Urban) and suburban areas.
