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.
DETERMINATION OF PHOSPHATE IN FOOD (VANADOMOLYBDATE METHOD)
AIM:
To determine phosphate content in a food sample.
APPARATUS:
Test tubes, colorimeter.
REAGENT:
Ammonium molybdate, ammonium vanadate, nitric acid.
PRINCIPLE:
Phosphate reacts with vanadomolybdate reagent to form a yellow complex.
PROCEDURE:
Prepare sample extract.
Add reagent and incubate for 10 minutes.
Measure absorbance at 400–420 nm.
CALCULATION:
Compare with phosphate standard curve.
DETERMINATION OF VITAMIN A (COLORIMETRIC METHOD)
AIM:
To determine the vitamin A content in margarine or food sample.
APPARATUS:
Test tubes, colorimeter, pipettes.
REAGENT:
Chloroform, antimony trichloride reagent (Carr-Price reagent).
PRINCIPLE:
Vitamin A reacts with antimony trichloride to form a blue complex, measurable colorimetrically.
PROCEDURE:
Extract sample with chloroform.
Add 2ml of Carr-Price reagent.
Measure absorbance at 620 nm.
Compare with vitamin A standard.
CALCULATION:
Use standard calibration curve to estimate µg vitamin A.
