Preparation and standardization of potassium Hydroxide:
Here we will understand how to do preparation and standardization of potassium hydroxide (KOH) as per USP.
Reagents required:
95% V/V Alcohol: Mix 95 ml of absolute alcohol into 5 ml of water.
Phenolphthalein Solution: Dissolve 1 g of phenolphthalein in 100ml of 95% alcohol.
Preparation of 1 N potassium hydroxide (KOH):
- Take 100 ml of volumetric flask.
- Dissolve 68 g of potassium hydroxide.
- Add freshly prepared saturated solution of barium hydroxide until no more precipitate forms.
- make up the volume to 950 ml.
- Allow it to stand overnight in a stoppered bottle.
- Decant the clear liquid or filter the solution in a tight polyolefin bottle.
For lower strength, the solution can be prepared as follows;
Quantity of KOH in g | Addition of water in ml | Strength of KOH |
34 | 950 | 0.5 N |
13.6 | 950 | 0.2 N |
6.8 | 950 | 0.1 N |
3.4 | 950 | 0.05 N |
0.68 | 950 | 0.01 N |
Standardization of 1 N KOH Solution:
- Dry the potassium biphthalate in 120°c for 2 hrs.
- Weigh previously crushed 5 g of potassium biphthalate in 75 ml of water.
- Add 2 drops of phenolphthalein solution.
- Titrate the solution with 1 N potassium hydroxide.
- The solution produces a permanent pink color.
Calculation formula of 1N KOH:
W
Normality of 1N KOH = ——————
0.20423 x V
Where,
W= Weight of potassium biphthalate in g
V= Volume of potassium hydroxide consumed in ml.
Preparation and standardization of potassium Hydroxide (KOH) in pharmaceuticals.
Also read:
- Preparation and standardization of 1N NaOH as per USP
- How to prepare 0.1N HCl?
- Difference between Assay, potency and purity
- 10 Principles of cGMP
- Karl Fischer titration interview Q&A
- Calibration of HPLC parameters
Refer YT Channel: Pharmabeej