#ASSAY OF CHLORPROMAZINE

Aim: To report the amount of chlorpromazine present in the given tablet/powder/solution

.

Apparatus: Burettes, pipettes, beakers, glass rod, funnel etc.

Chemicals: Perchloric acid, acetone, mercuric acetate solution, chlorpromazine drug

PHP(Potasium hydrogen Phthalate)

Principle:

           Assay of Chlorpromazine comes under non aqueous titration. In this assay the perchloric acid reacts with acetic acid and forms acetonium ion. Chlorpromazine in acetic acid acts as a base and accept a proton from acetonium ion and forms protonated chlorpromazine and acetic acid. The addition of mercuric acetate in the non-aqueous titrimetric method is based on the principle of removing the chloride counter ion so as to prevent the interference of the halide ion released by the titrant (acetous perchloric acid). The addition of mercuric acetate (which is undissociated in acetic acid) replaces the halide ion in chlorpromazine with a quantitative acetate ion which is a strong base in acetic acid .The addition of ascorbic acid solution prevents the formation of the red coloration due to the reduction of ascorbic acid to dehydroascorbic acid. Crystal violet is used as an indicator.

Procedure:

Standardization of 0.1M Perchloric acid

Place 0.02 gm of PHP in 100ml conical flask, dissolve in 10 ml Glacial acetic acid, add one drop of crystal violet solution and titrate against 0.1 M HClO₄.

Equivalent factor: Each ml of 0.1M HClO₄® 0.02042 gm of PHP.

Assay.

          Twenty tablets of each brand were accurately weighed and reduced to fine powder. From the powdered drug, an amount equivalent to 0.35g of chlorpromazine HCl were taken and transferred into a 250ml conical flask containing 50ml of glacial acetic acid. The mixture was shaken and 10ml of 5% w/v mercuric acetate, 2g of ascorbic acid and 2 drops of 0.2% w/v crystal violet indicator were added. The solution was stirred for 15 min with a magnetic stirrer and then titrated with 0.1M acetous perchloricacid to a blue end-point. Carry out a blank titration.

Equivalent factor:1 ml of 0.1 M perchloric acid is equivalent to 0.03553 g of C₁₇H₁₉ClN₂S

Calculations:      

Standardisation of 0.1M Perchloric acid

S. No	Contents in the flask	Burette Reading		Volume Consumed	Indicator
		Initial	Final
1
2

Each ml of 0.1M HClO₄ ≡ 0.02042 gm of PHP.

                               X ml of Y M of HClO₄ ≡ gms of PHP.

                                                         Y =

Assay:

S. No	Contents of the flask	Burette reading		Volume consumed	Indicator
		Initial	Final
1

1ml of 0.1M HClO₄≡ 0.03553 g of C₁₇H₁₉ClN₂S.

X ml of Y M HClO₄ ≡ Z gm of C₁₇H₁₉ClN₂S.

Z=

Percentage purity = Estimate amount / Weight of powder taken

Report:The percent purity of Chlorpromazine present in given sample is found to be …