study the presence of Insecticides and Pesticides in Various Fruits and Vegetables
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In the past decade there has been a tremendous increase in
the yields of various crops to meet the demand of
overgrowing population, achieved by using pesticides and
insecticides. These are chemicals that are sprayed over crop
to protect it from pests. For example, DDT, BHC, zinc
phosphide, Mercuric chloride, dinitrophenol, etc.
All pesticides are poisonous chemicals and are used in small
quantities with care. Pesticides are proven to be effective
against variety of insects, weeds and fungi and are
respectively called insecticides, herbicides and fungicides.
Most of the pesticides are non-biodegradable and remain
penetrated as such into plants, fruits and vegetables .
From plants they transfer to animals , birds and human
beings who eat these polluted fruits and vegetables. Inside
the body they get accumulated and cause serious health
problems. These days preference is given to biodegradable
insecticides like malathion. The presence of Insecticides
residues in even raw samples of wheat, fish, meat , butter
etc. have aroused the concern of agricultural administrators,
scientists and health officials all over the world to put a
check over the use of insecticides and to search for non
insecticidal means of pest control.
1)Take different types of fruits and vegetables and cut them into
small pieces separately.
2) Transfer the cut pieces of various fruits and vegetables into it
separately and crush them .
3) Take different kinds for each kind of fruits and vegetables and
place the crushed fruits and vegetables in these beakers and
add 100 ml of alcohol to each of these .
4) Stir well and filter. Collect the filtrate in separate china dishes,
Evaporate the alcohol by heating the china dishes one by one
over a water bath and let the residue dry in the oven .
5)Heat a small piece of sodium in a fusion tube , till it melts.
6) Then add one of the above residues from the china dish to this
fusion tube and heat it till red hot.
7)Drop the hot fusion tube in a china dish containing about 10
ml of distilled water.
8)Break the tube and boil the contents of the china dish for
about 5 minutes .
9) Cool and filter the solution. Collect the filtrate . To the filtrate
add 1 ml of freshly prepared ferrous sulphate solution and
warm the contents.
10) Then add 2-3 drops of ferric chloride solution and acidify
with dilute HCl. If a blue or green ppt. or colouration is
obtained it indicates the presence of nitrogen containing