Practicals

Question 1

Benedict’s test principle

Answer 1

Reducing sugars in urine in hot alkaline conditions form enediols
Enediols reduce cupric ions to red cuprois oxide.

Question 2

Benedict’s test procedure

Answer 2

5ml Benedict’s reagent + 0.5ml urine. Boil

Question 3

Rotheras test principle

Answer 3

Ketone bodies form purple complex with sodium nitroprusside and ammonia
Ferro Penta cyanide is formed

Question 4

Rotheras test procedure

Answer 4

1ml urine + solid ammonium sulphate.

5% sodium nitroprusside

Question 5

Gerhardts test principle

Answer 5

Acetoacetate with ferric chloride forms red brown ppt

Question 6

Gerhardts test procedure

Answer 6

5ml urine + 5% ferric chloride drop by drop

Question 7

Benzidine test principle

Answer 7

Heme of Hb decomposed H2O2 to nascent oxygen which oxidizes benzidine to bluish green product

Question 8

Benzidine test procedure

Answer 8

Benzidine + 1ml glacial acetic acid + 1ml H2O2 + urine

Question 9

Sulphosalicylic acid test principle

Answer 9

Proteins act as bases and react with acid to form insoluble salt of sodium sulphosalicylate

Question 10

Sulphosalicylic acid test procedure

Answer 10

2ml urine + 20% SSA

Turbidity observed

Question 11

Hays test principle

Answer 11

Bile salts lower ST of urine

Question 12

Hays test procedure

Answer 12

Urine + sulphur particles

They sink

Question 13

Fauchets test principle

Answer 13

BaCl2 reacts with sulfate to form Ba sulfate. It adheres to bilirubin.
Detected by oxidation of bilirubin to biliverdin with fouchets rgt

Question 14

Fouchets test procedure

Answer 14

5ml urine + 2 drops Mg sulfate + 5ml BaCl2.
Filter.
Add fouchets rgt to filter paper

Question 15

Ehlrich test principle

Answer 15

Urobilinogen reacts with Ehlrich rgt to give red colour intensified by sodum acetate

Question 16

Ehlrich test procedure

Answer 16

2ml urine + 2ml Ehlrich rgt.
Stand for 10 mins.
Add sodium acetate.