INDEX

1. ACKNOWLEDGEMENT2. CERTIFICATE3. BACKGROUND4. ROLE OF NICKEL5. PROPERTIES OF NICKEL6. AIM7. CHEMICALS REQUIRED8. APPARATUS9. PROCEDURE10. OBSERVATION11. RESULT12. CONCLUSION13. BIBILOGRAPHY

ACKNOWLEDGEMENT

On the completion of my project work on “TO STUDY THE IDENTIFICATION AND ESTIMATION OF NICKEL IN CHOCOLATES”. I grateful thank our teacher……………For her constant help and guidance to me without which this project would not have been success.

SHUBHAM MITTAL

CERTIFICATE

This to certify that SHUBHAM MITTAL has conducted that present work entitled “ TO STUDY THE IDENTIFICATION AND ESTI ATION OF NICKEL IN CHOCOLATES” . T he methods employed were undertaken by the candidate himself under my guidance.

……………………….

Signature

{Chemistry Teacher}

BACKGROUND

The future of any nation depends on the health, prosperity and progress of the forthcoming generation. In the present era of industrialization and development, one concern should be the health of the future generation. Children are the most vulnerable age group to any kind of contamination in the food chain. Chocolates and candies/toffees are the favorite food items of children and are often presented to them as token of love and affection from their parents and relatives.

Consumption of chocolates and toffees is not limited to a part of society. There are many types of locally made toffees and chocolates available in the market at a cheaper price than known brands. Out of these, only 60–70% have food labels listing ingredients on the wrappers. The most common ingredients listed are sugar, liquid

glucose, milk solids, cocoa solids, hydrogenated vegetable oil (HVO), vegetable fats, malt extract, soya solids, permitted emulsifier, salts, buffering agents, permitted stabilizer, sodium bicarbonate, cocoa butter, wheat flour, edible starches, vegetable oil, added flavor, soya lecithin, yeast and flour improvers, etc. Out of the above- mentioned ingredients, milk solids, cocoa solids, cocoa butter, hydrogenated vegetable oil, vegetable fats, permitted emulsifier, buffering agents and permitted stabilizer may be the source of nickel, lead and cadmium contamination.

Nickel, lead and cadmium contents were determined in 69 different brands of chocolates and candies available in local markets of suburban areas of Mumbai, 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 analyzed, 23 were cocoa-based, 22 milk-

based and another 24 were of fruit flavor and sugar-based. Cadmium level ranged from 0.001 to 2.73m g/g with an average of 0.105m g/g. Nickel ranged from 0.041 to 8.29m g/g with an average of 1.63m g/g and lead level ranged from 0.049 to 8.04m 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 numerous advertisements flashed in television and radio along with newspapers etc.

Since it is added in comparatively smaller amounts, it is considered quite insignificant from the health’s point of view. However, it has been reported that eating chocolates with nickel greater that certain amount might

cause premature graying of hairs. Deposition of nickel in significant amount can pose a major health hazard in the body.

ROLE OF NICKEL

NICKEL is added to chocolates for increasing their melting point and for preventing and for preventing it from melting at normal temperature.

Carrying out systematic qualitative analysis and quantitative analysis can identify presence of nickel by precipitating Nickel Di-methyl glyoxime .

ROLE OF NICKEL IN HUMANS

The ever increasing presence of nickel in nature and human food has made it the

subject of growing interest of research workers in various medical discipline. Its allergizing, toxic, mutagenic and carcinogenic causes justified concern of those who use it in orthopaedics and stomatology. The frequency of contact allergy to nickel has called attention to its use in production of many daily utility objects. The probability of allergy is not limited only to persons with occupational exposure to this element but it becomes ever more widespread in the whole population. The role of nickel in contact allergy is well known, and a particular feature of this allergy is the character of allergens which are simple haptens with respect to their antigenic. More detailed data on the mechanism of contact allergy have been provided by the discovery 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 in human serum. Is it believed it is involved in stabilizing the RNA structure . It also play role in functioning of enzymes oxidoreductases tranferases (like urea).

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 contact dermatitis, symptoms of which may

worsen if the diet is high in nickel. The oral toxic dose is 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 immune function. 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 dermarits (occupation),lungs and nasal caranomas, liver necrosis, 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 deleterious to children. The present study reports concentration of lead, nickel and cadmium in the chocolates and candies available in suburban areas of Mumbai, India.

NICKEL’s PROPERTIES

NICKEL is transition elements with atomic number 28 and has the configuration

1s2 2s2 2p6 3s2 3p6 4s2 3d8

As it has two unpaired electrons so it is paramagnetic.

Since there is partly filled orbital it exhibits various

properties like variable oxidation status, colored ions.

Catalytic properties but must important is formation of

complexes.

Nickel is silvery-white. hard, malleable, and ductile metal. It is of the iron group and it takes on a high polish. It is a fairly good conductor of heat and electricity. In its familiar compounds nickel is bivalent, although it assumes other valences. It also forms a number of complex compounds. Most nickel compounds are blue or green. Nickel dissolves slowly in dilute acids but, like iron, becomes passive when treated with HNO3

AIM

To identify nickel and estimate the amount of its presence in the chocolate.

CHEMICALS REQUIRED

1. Concentrated hydrochloric acid {HCL}2. Nitric acid {HNO3}3. Ammonium hydroxide {NH4OH}4. Ammonium chloride {NH4Cl}5. Alcohol6. Diethyl glyoxime7. Hydrogen sulphide

APPARATUS

1. Test tube2. Stand3. Filter paper4. Funnel5. Tongs6. Beaker7. Burner8. Water bath

Procedure

Take a few pieces of chocolate in a test tube. Add dilute HCL to dissolve 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. 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 Nickel sulphide and dissolve them in maximum quantity of aquaregia. Evaporate the solution to dryness. Dissolve the solid in dilute HCL and heat upto 80 degree Celsius. Add 1% alcoholic solution and add in slight excess. Immediately add NH4OH with constant stirring till the solution is slightly alkaline and give rise to red ppt. dimethly glyoxime.

Stir it well and allow it to digest on a water bath for half an hour, filter the ppt. dry it and burn it in a silica crucible , which is already weighed. Cool it and weight again.Difference of the two weights of silica crucible gives the amount of Nickel Di-methyl glyoxime.

OBSERVATION

QUALITATIVE ANALYSIS

S.NO

EXPERIMENTS OBSERVATION

INFRENCE

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. is obtained

Group IV is present {NI2+ or CO 2+ }

5 Sample solution +NH4OH +Di-methyl glyoxime

Red rose ppt. is obtained

Presence of nickel

CONCLUSION

NICKEL is present in the given chocolate.

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 +NOCL + 2H2O

Ni2+ 2C4H8N2O2 (aq) Ni (C4H7N2)O2 (S) +2H+

RESULT

S.NO SAMPLE PRESENCE OF NICKEL

1. Dairy milk shots Present2. Dairy milk Present3. Kit kat Present4. Bar one Absent5. 5 star Absent

PRESENCE OF NICKEL IN GIVEN SAMPLES IN INCREASING ORDER

5STAR < BAR ONE < KIT KAT < DAIRY MILK < DAIRY MILK SHOTS

CONCLUSION

The chocolate contains nickel in varying amounts though it’s not shown by the taste

BIBILOGRAPHY

1. N.C.E.R.T chemistry book2. Comprehensive chemistry

lab manual3. internet