[ps2id id=’background’ target=”/]
BACKGROUND
Principle: The acid value is the number which expresses in milligrams the amount of potassium hydroxide necessary to neutralise the free acids present in 1 g of the substance. Here direct titration is done taking a neutralized mixture of equal volumes of ethanol (95%) and ether as solvent and phenolphthalein as indicator.
Aim: To determine acid value of given oil/fat
Reaction:
[ps2id id=’requirements’ target=”/]
REQUIREMENTS
Chemical: Ethanol,
Ether
0.1 M potassium hydroxide,
Phenolphthalein
Apparatus: Volumetric flask
Pipette
Burette
[ps2id id=’procedure’ target=”/]
PROCEDURE
About 10 g (w) of the sample is dissolved, in 50 ml of a mixture of equal volumes of ethanol (95%) and ether, previously neutralised with 0.1 M potassium hydroxide to phenolphthalein solution. If the sample does not dissolve in the cold solvent, the flask is connected with a reflux condenser and slowly warmed, with frequent shaking, until the sample dissolves. 1 ml of phenolphthalein solution is added and titrated with 0.1 M potassium hydroxide until the solution remains faintly pink after shaking for 30 seconds.
Observation
| No. of
Observation |
Initial Burette Reading (ml) | Final Burette Reading (ml) | Difference (ml) | Average (ml) |
| 1 | n = | |||
| 2 | ||||
| 3 |
Calculation
Where, n = the number of ml of 0.1 M potassium hydroxide required;
w = the weight, in g, of the substance.
[ps2id id=’conclusion’ target=”/]
CONCLUSION
Acid value of the given oil/fat is …….
[ps2id id=’references’ target=”/][ps2id id=’1′ target=”/]
REFERENCES
- Indian Pharmacoepia 2010; Part I:84.
- Practical Pharmacognosy by Saroja Joshi and Vidhu Aeri; Published by Frank Bros. & Co. (Publishers) Ltd.; First Edition; 2009: 297.
- Hand Book of Analysis and Quality Control for Fruit and Vegetable Products, second edition by S. Ranganna, Published by Tata McGraw -Hill Publishing Company limited, New Delhi, Page No.- 224.
