VLD 421: Veterinary Clinical Biochemistry and Laboratory Diagnosis-II (0+1)

DETECTION OF ARSENIC

Aim

• To detect the presence of Arsenic in biological material.

Materials

• Pure zinc
• Hydrocholric acid (5N)
• 5% aqueous bromide solution

Procedure

• Before detecting the arsenic in biological sample the organic matter is to be destroyed. For this take 10 ml of aqueous saturated magnesium nitrate made alkaline with magnesium oxide and gently heat 20g of sample in it. The mass soften and chars. Then heat more strongly to give gray ash of magnesium pyroarsenate. Soak the ash in 25 ml of water ,filter and use the clear supernatant for test.
• Place a piece of mossy zinc (pure zinc) in a test tube with the unknown (supernatant)
• Add 5 ml of dilute hydrochloric acid (5N).
• When bubble are evolved hold the filter paper strip dipped in 5% aqueous mercuric bromide solution to the mouth of the tube.

Inference

• The paper turns yellow red indicates presence of arsenic.

SPOT TEST  FOR DETECTION OF ARSENIC

Aim

• To detect the presence of arsenic in biological materials.

 

Test	Procedure	Inferences
Test1	1 ml of test solution + a drop of 10% ammonium carbonate	No reaction
Test2	1 ml of test solution + a drop of 20% ammonium sulfide	Appearance of yellow forms slowly,when solution in excess.
Test3	1ml of test solution + a drop of 15% potassium iodide solution	No reaction.