DETERMINATION OF CHLOROPHYLL IN LEAF EXTRACT
AIM:
To estimate chlorophyll content in a leaf sample.
APPARATUS:
Spectrophotometer, centrifuge, test tubes.
REAGENT:
80% acetone.
PRINCIPLE:
Chlorophyll is extracted and measured at specific absorbance values.
PROCEDURE:
Grind 1g of leaf in 10ml acetone.
Centrifuge and collect supernatant.
Measure absorbance at 645 nm and 663 nm.
CALCULATION:
Use Arnon's formula:
Chlorophyll a = 12.7(A663) – 2.69(A645)
Chlorophyll b = 22.9(A645) – 4.68(A663)
DETECTION OF BORIC ACID IN FOOD
AIM:
To detect boric acid in food samples (e.g., milk, jaggery).
APPARATUS:
Test tubes, turmeric paper.
REAGENT:
None (turmeric paper acts as indicator).
PRINCIPLE:
Boric acid turns turmeric paper red, which turns green on ammonia exposure.
PROCEDURE:
Dip turmeric paper in food extract.
Dry and observe color.
Expose to ammonia vapor for confirmation.
RESULT:
Red to green color change confirms boric acid.
TEST FOR SULPHUR DIOXIDE IN DRIED FRUITS
AIM:
To detect presence of SO₂ preservative in food.
APPARATUS:
Test tubes, beaker.
REAGENT:
Pararosaniline hydrochloride, formaldehyde.
PRINCIPLE:
SO₂ reacts with dye and formaldehyde to form pink/magenta color.
PROCEDURE:
Boil fruit sample in water, cool extract.
Add 2ml dye reagent + formaldehyde.
Observe color change.
RESULT:
Pink color indicates presence of sulphur dioxide.
ALCOHOL DETECTION IN HAND SANITIZERS
AIM:
To determine the presence and concentration of alcohol in hand sanitizer.
APPARATUS:
Test tube, alcohol hydrometer or colorimeter.
REAGENT:
Potassium dichromate + sulfuric acid.
PRINCIPLE:
Alcohol reduces orange dichromate to green chromium ions.
PROCEDURE:
Add 2ml sanitizer to test tube.
Add dichromate reagent.
Shake and observe color change from orange to green.
RESULT:
Color change confirms alcohol; intensity can indicate concentration.
TEST FOR FORMALIN IN MILK
AIM:
To detect formalin (formaldehyde) in milk.
APPARATUS:
Test tube, ice bath.
REAGENT:
Sulfuric acid, ferric chloride.
PRINCIPLE:
Formalin reacts with ferric chloride and acid to give a violet ring.
PROCEDURE:
Take 5ml milk in a test tube.
Add 5ml sulfuric acid with FeCl₃ carefully along the wall.
Observe for a violet ring at the interface.
RESULT:
Presence of violet ring indicates formalin.
TEST FOR PRESENCE OF UREA IN MILK
AIM:
To detect adulteration of milk with urea.
APPARATUS:
Test tubes, dropper.
REAGENT:
Para-dimethylaminobenzaldehyde (PDAB) reagent.
PRINCIPLE:
Urea reacts with PDAB to form a yellow color.
PROCEDURE:
Add 5ml milk sample in a test tube.
Add 2ml of PDAB reagent.
Observe for yellow color development.
RESULT:
Yellow color indicates presence of urea.
