Mercury is one of the most toxic heavy metal found on earth it causes many decease, the main cause of mercury pollution is the mining industry and industrial effluent.

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2. Presentation Topic:
Presented by:
Assigned By:
Hg Analysis From The Fish And Their Effect on
Human Life By Using CVAAS Technique
Prof.Dr: Tasneem
Gul Kazi
DADU MAL(DK)
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3.  Introduction
 Mercury and its effects
 Applications of Hg
 Hg Pollution
 Hg Contamination through fishes
 Hg analysis from the fishes
 CVAAS
 Experimental work
 Application of AAS
 References
 Acknowledgement
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4. Atomic Absorption spectroscopy is a quantitative method of
analysis that is applicable to many metals and a few non metals.
This technique was introduced in 1955 by WALASH in Australia
Through this technique almost 70 elements can also be determined.
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5.  Discovered approximately 1500 BC
 Group 12, Period 6, Block d.
 Heavy transition metal.
 Found in air, water, and soil.
 It is liquid at room temperature .
 Mercury has long been known as quicksilver.
 Its vapors that are colorless, odorless, tasteless, & toxic.
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6.  Mercury forms useful compounds with other elements. Mercuric
chloride (HgCl2) is a very poisonous salt and was once used to
disinfect wounds.
Mercurous chloride (Hg2Cl2), also called calomel, is an antiseptic
used to kill bacteria.
Mercuric sulfide (HgS) is used to make a red paint pigment called
vermilion.
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7. Organomercury refers to the group of organometallic compounds that
contain mercury.
Typically the Hg–C bond is stable toward air and moisture but sensitive to light.
Important organomercury Compounds:
Methyl mercury(II) cation , CH3Hg+
Ethyl mercury(II) cation , C2H5Hg+
Dimethyl mercury , (CH3)2Hg
Diethyl mercury , (CH3CH2)2Hg
Merbromin ("Mercurochrome").
Thiomersal is used as a preservative for vaccines
and intravenous drugs.
Due to their toxicity and low nucleophilicity, organomercury
compounds find limited use. 7

8.  Coatings for mirrors.
 The most important use of mercury is in the preparation of Cl2.
 Mercury thermometers and barometers.
 Mercuric arsenate used as waterproofing paints.
 As a catalyst for chloralkali production.
 Used for extraction of Gold and Silver.
 Mercury chloride (calomel) electrode used in electro analytical techniques.
 In fluorescent lamps.
 As dental amalgam fillings.
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9. Mining has been a long-standing and continuing source of
environmental mercury contamination.
Hg pollution of inland waters is a global problem.
Among the sources of Hg pollution are coal-fired power plants, mining wastes,
chloralkali plants, and municipal waste incinerators.
 Mercury is released and cycled in the environment as either elemental
mercury, or various inorganic and organic forms.
In aquatic ecosystems, the inorganic forms of divalent mercury (Hg2+) in
sediment are converted to the more toxic organic form, CH3Hg.
Typically, 90% of the mercury found in fish is the CH3Hg form.
CH3Hg is produced inside sulfate-reducing bacteria. 9

10.  Vapors pass through the skin into the blood stream
through inhalation, and swallowed.
 Depression,nervousness,and personality changes.
 Damages the kidneys and muscles.
 Inflammation of the mouth and gums; loosening of
the teeth.
 Shaking, irritability, insomnia, confusion, excessive
salivation.
 Methyl-Hg or MeHg+ is a potent neurotoxin, damages
the central nervous system and especially toxic to
fetus.
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11.  Most exposure to mercury comes from
the ingestion of certain foods, such as
fish, in which the mercury has
accumulated at high levels.
 US food and drug Administration
regulation set a limit of 1 ppm mercury
being safe for man consumption.
 In 2002, these action limits were
lowered to 0.3 ppm to reflect the newly
discovered health risks associated with
the consumption of fish containing
elevated Hg concentration. 11

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 Advising pregnant women, and women
of childbearing age who may become
pregnant, and young children not to
eat identified large fish that
accumulate the highest levels of
CH3Hg.
 Aquatic organisms obtain CH3Hg from
water, sediment, and food.
 Inorganic mercury does not easily
transfer into food webs and does not
biomagnify.
 CH3Hg is a neurotoxin that can cause
incoordination, poor appetite or
feeding behavior, lessened swimming
activity, starvation, and eventually
mortality.

13.  According to US EPA, number of regulatory methods that
are available.
 Cold Vapor Atomic Absorption Spectroscopy (CVAAS)
 Cold Vapor Atomic Fluorescence Spectroscopy (CVAFS)
 Direct Analysis by Thermal Decomposition
 ICP or ICP-MS
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14.  CVAAS is one of the primary techniques for mercury analysis.
 Introduced in 1968 by Hatch and Ott, in order to get
maximum analytical performance and measurement accuracy
for mercury concentrations from 1 ppt to 100 ppm.
 This so-called "cold vapor atomic absorption spectroscopy"
(CVAAS) is extremely sensitive for mercury determination and
has been used successfully over a period of many years.
The cold vapor atomic absorption technique is widely used for
mercury trace analysis because of its simplicity, robustness, and
relative freedom from interferences.
 Excellent detection limits can be achieved with our modern
instruments.
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15. REAGENTS:
All the solutions were prepared in water with a resistivity
of 18.2 MΩ cm-1 ,obtained from mili-Q water purifier system.
The chemical used were of analytical grade.
Mercury(II) working standards were prepared by appropriate dilution
1000 mg L-1 in H2SO4 10% v/v and stabilized by addition of 1-2 drops
of a 5% v/v KMnO4 solution.
The NaBH4 alkaline solution were prepared by dissolving the
appropriate 3% v/v HCl solution and Argon C-45 was used as a carrier
gas.
ACID DIGESTION:
For sample digestion 10% m/v NH2OH.HCl solution
were prepared,5% m/v KMnO4 solution were prepared ,Mercury free
salt conc: H2SO4. Antifoam 1- octanol was employed to avoid foam
formation in sample analysis.
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16. We analyzed fish sample(Shellfish ,cod ,skate , prawn, squid) that
were commercially available and a certified reference material
(Dogfish Muscle) from NCEAC.
A 5-g portion of fresh fish or 0.5 g of dried fish (NCEAC) was
introduced in a digestion flask with 5 ml of water and 10 ml of
H2SO4.
The sample was left overnight at room temperature. Small aliquots
of 5% v/v KMnO4 solution were added to the digest to obtain
permanent pink color, which should persist for at least 4 h.
The excess of KMnO4 was removed by the addition of a 10% m/v
NH2OH.HCl solution.
2-3 drops of 1-octanol was added to prevent excessive foam during
analysis.
The sample solution was stabilized by the addition of 1-2 drops of
KMnO4 and the mixture was diluted to 100 ml with water.
A reagent blank was also exposed alongside the sample. 16

17. A Perkin Elmer Model 4100ZL atomic absorption
spectrometer equipped with a mercury hollow
cathode lamp was used.
The analytical wavelength and slit were 253.7
nm and 0.7 nm respectively.
Argon, with a purity of 99.996% was used as the
carrier gas.
In each digester tube a cold finger was
introduced to avoid losses by volatilization of Hg
and reagents.
All the instrument were controlled by Perkin
Elmer AA-Winlab software.
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19. CVAAS systems are more sensitive, automated, smaller, faster and
less expensive than the early generic flame photometers with the cold
vapor attachments. Modern models provides trace ultra trace analysis
detection limits of ng/L and can analyze sample in a mint.
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20. *Determination of Mercury in Fish by Cold Vapor Atomic Absorption
Spectrophotometry Using a Multicommuted Flow Injection Analysis
System
*M. Fátima SILVA, Ildikó V. TÓTH, and António O. S. S. RANGEL
*http://www.food.gov.uk/multimedia/pdfs/constatment/
mercuryfish.PDF, accessed June 16, 2005.
* 2. Toxicological Effects of Methylmercury,
http://www.nap.edu/openbook/0309071402/html/R1.html.
copyright.2000, The National Academy of Sciences, accessed June 16,
2005.
*5. “Foodstuffs—Determination of trace elements-determination of
mercury by cold-vapour atomic absorption spectrometry (CVAAS)
after pressure digestion”, European Standard EN 13806:2002. 6. J. C.
Andrade, C. Pasquini, N. Baccan, and J. C. V. Loon.
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21.  I am very thankful to Almighty ALLAH for
His divine support.
 And thankful to Prof Dr:TASNEEM GUL
KAZI for giving such a good platform to
enhance our skills and for his kind support.
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