Preparation and standardization of 0.1N perchloric acid VS as per USP:
Multiple volumetric solutions are used in the pharmaceutical industry, here is the manual and potentiometric method of preparation and standardization of 0.1N perchloric acid VS as per USP.
The reagent used in the standardization of perchloric acid:
Crystal Violet: Dissolve 0.1g crystal violet in 100ml of anhydrous glacial acetic acid.
Preparation of 0.1N perchloric acid in glacial acetic acid:
- Mix 8.5ml perchloric acid (70%) with 500ml of glacial acetic acid and 21 ml of acetic anhydride. or Mix 11 ml of 60% perchloric acid with 500ml of glacial acetic acid and 30 ml of acetic anhydride.
- Cool the solution and add the glacial acetic acid to make 1000ml.
- Allow the solution to stand for 1 day for the excess of acetic anhydride to be combined.
- Determine the water content, if water content exceeds 0.5% add more acetic anhydride.
- Allow to stand for 1 day and determine the water content.
- If the solution contains no titrable water, add a sufficient amount of water to obtain water between 0.02% and 0.5% water.
Manual Standardization of 0.1N perchloric acid:
- Dry the potassium hydrogen phthalate at 120°c for 2 hrs.
- Crushed and weigh accurately 700mg of dried potassium hydrogen phthalate.
- Dissolve it in 50 ml of glacial acetic acid.
- Add 2 drops of crystal violet and titrate with 0.1N perchloric acid solution.
Potentiometric standardization of 0.1N perchloric acid:
- Refer manual standardization up to Point No.3.
- Titrate with 0.1N perchloric acid potentiometrically by using pH glass electrode.
- Carry out the blank determination by omitting potassium hydrogen phthalate.
Normality Calculation of 0.1N Perchloric acid:
W x 0.1
Normality = ———————————
0.020422 x (Vs-Vb)
W= weight of potassium hydrogen phthalate taken in gm
Vs= Volume of perchloric acid consumed for the test
Vb=Volume of perchloric acid consumed for the blank
Restandardization of Solution:
Restandardize before use and not Valid beyond a day.
This is of preparation and standardization of 0.1N perchloric acid VS is as per USP.
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