Limit Test of Chloride
Limit test of chloride is based on the reaction of soluble chloride with silver nitrate in presence of dilute nitric acid to form silver chloride, which appears as solid particles (Opalescence) in the solution.
|Test sample||Standard compound|
|Specific weight of compound is dissolved in water or solution is prepared as directed in the pharmacopoeia and transferred in Nessler cylinder||Take 1ml of 0.05845 % W/V solution of sodium chloride in Nessler cylinder|
|Add 1ml of nitric acid||Add 1ml of nitric acid|
|Dilute to 50ml in Nessler cylinder||Dilute to 50ml in Nessler cylinder|
|Add 1ml of AgNO3 solution||Add 1ml of AgNO3 solution|
|Keep aside for 5 min||Keep aside for 5 min|
|Observe the Opalescence/Turbidity||Observe the Opalescence/Turbidity|
The opalescence produce in sample solution should not be greater than standard solution. If opalescence produces in sample solution is less than the standard solution, the sample will pass the limit test of chloride and visa versa.
Nitric acid is added in the limit test of chloride to make solution acidic and helps silver chloride precipitate to make solution turbid at the end of process.