Sulfate limit test(IP/BP/USP)

 AS PER IP

Requirements:

Nessler's cylinder, measuring cylinder, glass rod, potassium sulphate, standard solution, Hcl, barium sulphate reagent and distilled water

10 ppm Sulfate Standard Solution, ethanolic:

Dissolve 0.181gm of dipotassium sulfate(K2SO4) in 100 ml of ethanol (30 per cent).

Barium Chloride solution:

Dissolve 250 gm of barium chloride in 1000 ml of distilled water.

5 M Acetic Acid: 

prepare by diluting 285ml(300g) of glacial acetic acid to 1000 ml with water.

Procedure:

Standard:

To 1.0 ml of a 25.0 per cent w/v solution of barium chloride in a Nessler cylinder(50ml) add 1.5 ml of ethanolic sulphate standard solution (10 ppm SO4 ), mix and allow to stand for 1 minute. 

Add 15 ml of sulphate standard solution (10 ppm SO4) and 0.15 ml of 5 M acetic acid. Add sufficient water to produce 50 ml, stir immediately with a glass rod and allow to stand for 5 minutes.

Observe opalescence after 5 minutes.

Sample:

To 1.0 ml of a 25.0 per cent w/v solution of barium chloride in a Nessler cylinder(50ml)  add 1.5 ml of ethanolic sulphate standard solution (10 ppm SO4 ), mix and allow to stand for 1 minute. 

Add 15 ml of the solution prepared as directed in the monograph or a solution of the specified quantity of the substance under examination in 15 ml of water and 0.15 ml of 5 M acetic acid. Add sufficient water to produce 50 ml, stir immediately with a glass rod and allow to stand for 5 minute

Observe opalescence after 5 minutes.

Interpretation

When viewed transversely against a black background any opalescence produced for the sample is not more intense than the standard.

Note:  All solutions used for this test must be prepared with distilled water.

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AS PER BP

Requirements:

Nessler's cylinder, measuring cylinder, glass rod, potassium sulphate, standard solution, Hcl, barium sulphate reagent and distilled water

10 ppm Sulfate Standard Solution:

Dissolve 0.181gm of dipotassium sulfate(K2SO4) in 100 ml of distilled water.

Barium Chloride solution:

Dissolve 250 gm of barium chloride in 1000 ml of distilled water.

Procedure:

Standard:

Take 4.5ml of the sulfate standard Solution in Nessler cylinder, add 3 ml barium chloride solution shake and allow to stand for 1 minute.

Take 50 ml Nessler cylinder, take 2.5 ml of above suspension add 15 ml of sulfate standard solution(10ppm) and add 0.5ml of acetic acid and make up to 50ml with distilled water.

Observe opalescence after 5 minutes.

Sample:

Take 4.5ml of the sulfate standard Solution in Nessler cylinder, add 3 ml barium chloride solution shake and allow to stand for 1 minute.

Take 50 ml Nessler cylinder, take 2.5 ml of above suspension add 15 ml of sulfate standard solution(10ppm) and add 0.5ml of acetic acid and make up to 50ml with distilled water.

Observe opalescence after 5 minutes.

Interpretation

After 5 min, any opalescence in the test solution is not more intense than that in the  standard. 

Note:  All solutions used for this test must be prepared with distilled water. 

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AS PER USP

Barium Chloride TS: Dissolve 12gm of barium Chloride in water to make 100ml

Sample:

Dissolve the specified quantity of the substance under test in 30 to 40 mL of water, or, where the substance is already in solution, add water to make a total volume of  30 to 40 mL, and, if necessary, neutralize the solution with hydrochloric acid to litmus(Ref: When blue litmus paper is placed in an acidic solution, it becomes red). 

Add 1 mL of 3 N hydrochloric acid, 3 mL of barium chloride TS, and sufficient water to make 50 mL. Mix, and allow to stand for 10 minutes. 

Standard:

Unless otherwise specified in the monograph, compare the turbidity, if any, with that produced in a solution containing the volume of 0.020 N sulfuric acid specified in the monograph

Example: 

In dibasic calcium phosphate, 

Sample

Dissolve 1.0gm in smallest amount of 3N hydrochloric acid dilute to 100ml and filter, if necessary. To 20 ml of the filtrate add 1ml of barium chloride TS.

Standard

1.0 ml of 0.020N sulfuric acid (0.5%)

Interpretation:

When viewed transversely against a black background any opalescence produced for the sample is not more intense than the standard.