AMOUNT OF NICKELCONTENTPRESENT IN VARIOUS BRANDS OF CHOCOLATES

2. On the completion of my project work on:
‘TO STUDY THE AMOUNT OF NICKELCONTENTPRESENT
IN VARIOUS BRANDS OF CHOCOLATES.”
I gratefully thank my teacher Mr. Amit, his constant help
and guidance to me without which this project would not have been
success.

3. This to certify that “Kumar Nitin” hasconducted the present work entitled.
‘TO STUDY THE AMOUNT OF NICKEL CONTENTPRESENT IN VARIOUS
BRANDS OF CHOCOLATES.”
The methods applied were undertaken bythe candidate himself under my
guidance.
……………………
Signature
(Chemistry Teacher)

5.  BACKGROUND
 ROLE OF NICKEL
 ROLE OF NICKEL IN HUMAN BEINGS
 PROPERTIES OF NICKEL
 TOXICITY
 EXPERIMENT
 BIBILOGRAPHY

6. Nickel, lead and cadmium are determined in the different brands of chocolates and
candies available in the markets of sub urban areas of Delhi, India.
The majority of these chocolates and candies are made mainly from cocoa, milk solids,
dry fruits, fruit flavors and sugar. Out of 69 brands of chocolates and candies recognized,
23 were cocoa based, 22 milk based, and another 24 were fruit flavors and sugar based.
Cadmium level ranged from 0.001 to 2.73m g/g with an average of 1.63 m g/g and lead
level ranged from 0.049 to 8.04 m g/g with an average of 0.93m g/g. cocoa based
chocolates are found to have higher contents of the analyzed heavy metals than milk
based chocolates, fruit flavor, or sugar based candies.
Very few people are aware of the fact that nickel is present in chocolates since it is never
mentioned in the ingredients or the advertisements in TV, radio, newspaper etc.It is not
considered significant from the health’s point of the view as it is added in comparatively
smaller amounts.However,it has been reported that eating chocolates with nickel greater
than certain amount might cause significant physical or mental symptoms like premature
greying of hair etc. Deposition of nickel in body in significant amounts can cause major
lung diseases, even death.

7. Role of Nickel
NICKEL is added to chocolates for increasing their melting
point and for preventing it from melting at normal
temperature.Carrying out systematic qualitative
andquantitative analysis can identify presence of nickelby
precipitating Nickel Di-methyl glyoxime.

8. ROLE OF NICKEL IN HUMAN BEINGS
The ever increasing presence of nickel in nature andhuman food has made it the subject of
growing interestof research workers in various medical discipline. Itsallergy causing, toxic,
mutagenic and carcinogenic causes justified concern of those who use it in orthopedics
andstomatology. The frequency of contact allergy to nickelhas called attention to its use in
production of manydaily utility objects. The probability of allergy is notlimited only to
persons with occupational exposure to this element but it becomes ever more widespread in
thewhole population. The role of nickel in contact allergy iswell known, and a particular
feature of this allergy is the character of allergens which are simple hap tens withrespect to
their antigenic. More detailed data on themechanism of contact allergy have been provided
by thediscovery of Langerhans cells which have the ability of antigen presentation.
Considering the role of nickel in pathological conditions we must not forget its
great physiological importance as a microelement necessary for life.
About 0.02% micron molecule of nickel is present inhuman serum. It is believed that it is
involved in stabilizing the RNA structure. It also playsan important role in functioning
of enzymes like urea.

9. NICKEL’s PROPERTIES
 NICKEL is transition elements with atomic number 28 and
has the configuration: 1s22s22p63s23p64s23d8 .
 It has two unpaired electrons so it is paramagnetic.
 Nickel is silvery-white. Hard, malleable, and ductilemetal.
 It is a fairly good conductor of heat andelectricity.
 . Nickel dissolves slowly in dilute acidsbut, like iron,
becomes passive when treated with HNO3
 Most nickel compoundsare blue or green.

10. TOXICITY
Toxicity has occurred in workers exposed to nickel dust or nickel carbonyl formed in refining.
Increased risk of nasal and lung cancers was linked to occupational nickel exposure before
current workplace safety standards were set. Environmental sources of lower levels of nickel
include tobacco, dental or orthopedic implants, stainless-steel kitchen utensils and
inexpensive jewelry. Repeated exposures may lead to asthma and dermatitis (on contact),
symptoms of which may worsen if the diet is high in nickel. The oral dose is toxic about 1000
times the amount consumed in food. Different chemical forms vary widely in toxicity.
Excessive nickel in tissues is pro-oxidant (damaging chromosomes and other cell
components) and alters hormone and enzyme activities, movement of ions through
membranes, and immunity system. These effects can change glucose tolerance,
blood pressure, response to stress, growth rate, bone development and resistance to
infection. Under some conditions, large amounts of nickel may precipitate magnesium
deficiency or cause accumulation of iron or zinc.
Nickel can cause dermatitis, liver necrosis and pulmonary inflammation.This work has been
done in view of the toxic effects of these heavy metals and their presence in chocolates,
which can be pernicious to children.

11. Experiment
AIM
TO STUDY THE AMOUNT OF NICKEL CONTENT PRESENT IN VARIOUS BRANDS OF
CHOCOLATES.
CHEMICALS REQUIRED
1. Concentrated hydrochloric acid {HCL}
2. Nitric acid {HNO3}
3. Ammonium hydroxide {NH4OH}
4. Ammonium chloride {NH4Cl}
5. Alcohol
6. Diethyl glyoxime
7. Hydrogen sulphide

12. APPARATUS REQUIRED
 Test tube
 Stand
 Filter paper
 Funnel
 Tongs
 Beaker
 Burner
 Water bath

13. PROCEDURE:
 Take a few pieces of chocolate in a test tube and add dilute HCL todissolve it.
 Apply usual chemical test to confirm the presence of Nickel in it. For quantitative
estimation take a weighed amount of Chocolate in a beaker and add dilute HCL and shake
it till it dissolves completely.
 Filter the solution & add sufficient amount of NH4OH till it is alkaline.Through the
solution, pass H2S gas till complete precipitation of nickel sulphide takes place. Filter the
black ppt. of Nickelsulphide and dissolve them in maximum quantity of aquaregia.
 Evaporate the solution to dryness and dissolve the solid in dilute HCL and heat up to 80
degree Celsius.
 Add 1% alcoholicsolution and add in slight excess. Immediately add NH4OH with constant
stirring till the solution is slightly alkaline andgives rise to red ppt. dimethyl glyoxime.Stir it
well and allow it to digest on a water bath for half anhour, filter the ppt. , dry it and burn it
in a silica crucible , whichis already weighed. Cool it and weight again.
 Difference of the two weights of silica crucible gives the amountof Nickel Di-methyl
glyoxime.

14. OBSERVATION
S.NO EXPERIMENTS OBSERVATIONS INFERENCE
1. Sample + dil. HCL Sample dissolves Absence of 1st
group.
2. Sample solution + dil.HCL.Pass H2S
gas.
Ppt. not obtained. Absence of 2nd
group.
3 Boil off H2S gas. Add NH4CL and
NH4OH in solution.
Ppt. not obtained. Absence of 3rd
group.
4. Pass H2S gas. Black ppt. obtained. Group IV is present
5. Sample solution + NH4OH + Di-
methyl glyoxime.
Red ppt. obtained Presence of nickel.
QUALITATIVE ANALYSIS:

15. REACTION
Nickel is confirmed by formation of bright red ppt. with DMG after dissolution
of NiS in aqua regia.
NiS + 4H+ + Cl- + NO3
+  Ni2+ + S + 2H2O
(Nickel (Chloride (Nickel (Sulphur) (Water)
Sulphide) ion) ion)
NiSO4 + 2C4H8O2N2  Ni{ C4H7O2N2}2 + H2SO4
(Nickel (Dimethyl (Nickel) (Sulphuric acid)
Sulphate) glyoxime) (Red colour ppt)

16. S. NO. SAMPLE PRESENCE OFNICKEL
1 Dairy milk shots Present
2 Dairy milk Present
3 KitKat Present
4 Barone Absent
5 5Star Absent

17. PRESENCE OF NICKEL IN GIVEN SAMPLESIN INCREASING ORDER
5STAR < BAR ONE < KIT KAT < DAIRY MILK < DAIRYMILK SHOTS
CONCLUSION
The chocolate contains nickel in varying amounts though it is not shown by
the taste.

18. BIBILOGRAPHY
 N.C.E.R.T chemistry book
 Comprehensive chemistry labmanual
 Internet