NON-AQUEOUS TITRATIONS PART-2; MCQ for GPAT, Pharmacist, NET JRF and GATE

DETECTION OF END POINT :-

  • Visual indicator are formed to the most suitable for the detection of end point in non-aqueous Titration
  • There are following important indicator are used in non aqueous Titration are as follows :-

1. Indicator :crystal violet

• composition of indicator W/V :- 0.5% in glacial acetic acid

•colour change :-

  1.  Basic :- violet
  2. Neutral :- blue – green
  3. Acidic :- yellowish- green

2. Indicator :– 1-Naphthol benzenein

• Composition of indicator W/V :- 0.2% -1% glacial acetic acid

•colour change :-

  1.  Basic :- blue
  2. Neutral :- orange
  3. Acidic :- dark green

3.Indicator :- oracet blue B

• composition of indicator W/V :- 0.5 acetic acid

•colour change :-

  1.  Basic :- blue
  2. Neutral :- purple
  3. Acidic :- pink

4. Indicator :- Quinaldine red

• composition of indicator W/V :- 0.1% methanol

•colour change :-

  1.  Basic :- magenta
  2. Neutral :- –
  3. Acidic :- colourless

5. Indicator :- Thymol blue

• composition of indicator W/V :- 0.2 % methanol

•colour change :-

  1.  Basic :- yellow
  2. Neutral :-
  3. Acidic :- blue

Assay by non – aqueous Titration :-

It can be divided into two heads :-

1. Acidimetry :- this can be further divided into two groups

  1. Titration of primary, secondary and tertiary amine.
  2. Titration of halogen acid salts of bases.

2. Alkalimetry in non aqueous Titration :-

Titration of acidic substance.

• ACIDIMETRY IN NON AQUEOUS TITRATION :-

Example Is primary amine :-

Methodology :-

  1. Preparation of 0.1 M perchloric acid
  2. Standardization of 0.1 M perchloric acid
  3. Choice of indicator
  4. Effect on temp. On assay

1.Preparation of 0.1 M perchloric acid :-

  • 8.5 ml of perchloric acid (72%w/w) to 500 ml of anhydrous glacial acetic acid with continue & efficient mixing.
  • Add 25 ml of acetic & anhydrous and cool
  • Add  anhydrous glacial acetic acid to produce 1000 ml.
  • Allow it to stand for 24 hour before use.
  • Determination the moisture & Acetic anhydride content.
  • Water content should not exceed 0.05% add more acetic anhydride.
  • If the solution contains no. Titratable water add sufficient water to obtain content of water between 0.02-0.05%.
  • Excess acetic anhydride is not always advantageous.
  • Care must be taken in case of primary & secondary amine.
  • The perchloric acid must be diluted with acetic acid before adding the acetic anhydride failure to observe this precaution leads to formation of explosives acetyl perchlorate.
  • Other strength can be prepared by diluting it with anhydrous glacial acetic acid.

STANDARDISATION 0.1 M PERCHLORIC ACID :-

  • Alkali & alkali earth metal e.g potassium hydrogen phthalate function as base in acetic acid solution.
  • It can be used as primary standard for standardising the acetous perchloric acid

Method :-

  • 0.35 g of potassium Hydrogen phthalate previously dried at 120º C for 2 hours.
  • Dissolve it in 50 ml of glacial acetic acid.
  • Add 0.1 ml of crystal violet solution.
  • Titrate with the perchloric acid solution until the violet colour change to green
  • Perform the blank & make necessary corrections.

EXAMPLE OF DRUG THAT DETERMINED BY THIS METHOD

Adrenaline Lova DOPA capsule
Atropine methonitrate Mebendazole
Caffeine Noscapine
Chloroquine phosphate Nicotinamide
Cimetidine Phenytoin
Codine phosphosphate Pilocarpine nitrate
Diazepam Quinidine sulphate
Ergometrin maleate Salbutamol sulphate

 

MCQ

1. Diazepam is Assay by which method ?

A. Acid base titration

B.Non aqueous titration

C. Karl fischer titration

D. NMR

2. Which indicator give magenta in basic medium ?

A. Quinaldine red

B. 1-Naphthol benzenein

C.Oracet blue B

D.Thymol blue

3. How many percentage of acetic acid in oracet blue B ?

A.0.3% w/v

B.0.5 % w/v

C.0.2%  w/v

D.0.1% w/v

4.Which indicator give  yellow colour in basic medium ?

A. Crystal violet

B. 1-Naphthol benzenein

C.Oracet blue B

D.Thymol blue

5.Pilocarpine nitrate  is Assay by which method ?

A. Acid base titration

B.Non aqueous titration

C. Karl fischer titration

D. NMR

6. How many w/v of methanol present in Quinaldine red ?

A. 0.3

B.0.2

C.0.1

D.0.4

7.Nicotinamide  is Assay by which method ?

a. Acid base titration

b.Non aqueous titration

c. Karl fischer titration

d. NMR

8.Atropine methonitrate  is Assay by which method ?

A. Acid base titration

B.Non aqueous titration

C. Karl fischer titration

D. NMR

ANSWER KEY

1.B

2.A

3.B

4.D

5.B

6.C

7.B

8.B

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REFERENCE :- 

TEXT BOOK OF PHARMACEUTICAL ANALYSIS THIRD EDITIONS BY DR.S.RAVI SANKAR (PG.NO.19.1 TO 19.12)

 

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