Experiment no. 2 Limit test for sulphates.pptx

In this experiment I have provided the complete information regarding limit test for sulphate and also preparation of 0.1 N sulphuric acid and barium sulphate reagent for your better understanding.

1. EXPERIMENT NO:2 LIMIT TEST FOR SULPHATES Prepared by Dr Anumalagundam Srikanth Dept. of P harmaceutical Analysis

2. LIMIT TEST Theory : limit test are the quantitative and semi quantitative test designed to identify and control small quantity of impurities which are likely to be present in the drugs or pharmaceutical substance. (or) Limit test are used for identify and control small quantity of impurities in drugs.

3. Aim: T o carry out the limit test for Sulphates . Apparatus : Nessler’s cylinders 50 ml 2 nos., beakers, glass rod etc…, Materials: Sodium chloride (NaCl) (sample which does not contains chlorides) Sulphuric acid (H 2 SO 4 ) Hydrochloric acid (HCl) Barium chloride (BaCl 2 ) Potassium sulphate (K 2 SO 4 ) Alcohol

4. Solutions : Sulphuric acid ( 0.1 M) : 5.4 ml of sulphuric acid and dilute up to 1000 ml with distilled water. Assay of H 2 SO 4 normally available was 96 % - 98 % ( 98 ml in 100 ml / likely 980 ml in 1000 ml ) Density of HCl was 1.8 Density = mass/ volume Mass = density X volume Mass= 1.8 X 980 = 1764 gm No. of moles present in H 2 SO 4 No.of moles present in sample = weight of sample / molecular weight For H 2 SO 4 = 1764 ( weight of H 2 SO 4 ) / 98 (M.W) = 18 N of H 2 SO 4

5. We need to prepare 0.1 N by using the formula N 1 V 1 = N 2 V 2 Where N 1 = 18 , V 1 = ? , N 2 = 0.1 , V 2 =1000 18 X v 1 = 0.1 X 1000 V 1 = 0.1 X 1000/18 = 5.4 ml

6. Barium sulphate reagent (BaSO 4 ): Mix 15 ml of 0.5% barium chloride (BaCl 2 )with 55 ml of water and 20ml of sulphate free alcohol and 5 ml of 0.0181 % of Potassium sulphate (K 2 SO 4 ). Dilute to 100 ml with distilled water. Always use freshly prepared Barium sulphate reagent (BaSO 4 ).

7. PRINCIPLE : The limit test for Sulphate is mainly used to control sulphate impurities in inorganic substances. If depends upon the precipitation of the sulphate with Barium sulphate reagent (BaSO 4 ) in the presence of HCl. The turbidity so obtained is compared with standard turbidity contain a known amount of sulphate ion. T he reaction involved is as follows. H 2 SO 4 + BaCl 2 BaSO 4 + 2HCl

8. PROCEDURE: Sample : Dissolve the specified quantity of the NaCl in 10 ml of distilled water and transfer to a Nessler cylinder or glass. Add 2 ml of dil.HCl . Dilute to 45 ml with distilled water. Add 5 ml of BaSO 4 reagent. Stirr immediately with a glass rod, and set a side for 5 min the turbidity produced is not greater than the standard turbidity.

9. Standard : Take 2.5 ml of 0.1 H 2 SO 4 and transfer to a Nessler cylinder. Add 10 ml of dil.HCl . Dilute to 45 ml with distilled water. Add 5 ml of BaSO 4 reagent. Stirr immediately with a glass rod, and set a side for 5 min.

10. Observation : Standard shows more turbidity than sample. Report : T he given sample was passes limit test of sulphates . References: Practical pharmaceutical inorganic chemistry by Dr.G.Devala Rao., Birla publications Pvt.Ltd., N ew Delhi. Page no: 38. IP 1985