limit test for sulphate

LIMIT TEST FOR SULPHATE

1. LIMIT TEST FOR SULPHATE BY PROF. TAUFIK MULLA ASSISTANT PROFESSOR DEPARTMENT OF PHARMACEUTICS SPBC COLLEGE OF PHARMACY.

2. Limit test for SULPHATE The Sulphate Limit Test is designed to determine the allowable limit of sulphate contained in a sample. The principle involved in the Limit test of sulphates is precipitation method and comparison of test solution with standard solution containing a known amount of sulphates. Principle: The sulphates are precipitated as barium sulphate by reacting with barium chloride in the presence of acetic acid. The acetic acid used prevents the reaction of other acid radicals with barium chloride. In presence of hydrochloric acid, only sulphates are precipitated. Sulphate ion Barium Chloride Barium Sulphate

3. Due to the formation of precipitates, the solution appears turbid and the extent of turbidity depends on the amount of sulphates present. If the turbidity produced by the test is less than that of standard, it means that the sample contains sulphates within the prescribed limits.

4. PROCEDURE TEST SAMPLE STANDARD SAMPLE REASON Take 1 ml of 25% w/v of barium chloride in Nessler cylinder and marked it as ‘T’ Take 1 ml of 25% w/v of barium chloride in Nessler cylinder and marked it as ‘S’ Barium ion react with sulphate and produced opalescence of barium sulphate Add 1.5 ml of ethanolic sulphate standard solution (10 ppm of SO4) Add 1.5 ml of ethanolic sulphate standard solution (10 ppm of SO4) Ethanolic sulphate solution increase sensitivity of test and alcohol prevent super saturation barium sulphate precipitate Add 15 ml solution of given sample Add 15 ml standard potassium sulphate solution as per I.P For presence of sulphate ion in sample and standard Add 0.15 ml 5M acetic acid Add 0.15 ml 5M acetic acid To prevent precipitation of other anions Make volume with distilled water to 50 ml Make volume with distilled water to 50 ml Equal volume of sample and standard is needed to identify opalescence

5. conclusion The opalescence produced in the sample solution should not be greater than standard solution. If opalescence produced in the standard is more than that of test, the sample complies with the limit test of sulphate as per I.P. 1996