HPLC ASSAY METHOD OF ASPIRIN

Preparation of Mobile phase :- Dissolve 2gms of sodium 1-heptasulphonate in a mixture of 850ml of water and 150ml of acetonitrile,and adjust with glacial acetic

acid to a pH of 3.4.

Diluting solution : Prepare a mixture of acetonitrile and formic acid (99:1)

Standard preparation : Dissolve an accurately weighed quantity of USP Aspirin RS in diluting solution to obtain a solution having a known concentration of about 0.5mg/ml

Assay preparation:  Weigh and finely powder not less than 20 tablets. Transfer an accurately weighed quantity of powder ,equivalent to about 100mg of aspirin ,to a suitable container. Add 20ml of diluting solution and about 10 beads. Shake vigorously for about 10 minutes, and centrifuse (Stock Solution).

Quantitatively dilute an accurately measured volume of the stock solution with

9 volumes of diluting solution (Assay preparation).

Chromatographic System :

Column                : 4.0mm X 30cm containing packing L1

Flow rate              : 2ml per minute.

Wavelength          : 280nm.     

Temperature                  : Ambient

Injection volume   : about 10µL.

Procedure : Seperately inject an equal volumes (about 10µL) of Standard preparation and Assay preparation into the chromatograph , record the chromatograms,and measure responses for the major peaks.

Calculate the quantity,in mg,of the aspirin (C₉H₈O₄) in the portion of the

tablets taken by the formula :

                                     200C(ru / rs),

In which C is the concentration, in mg per ml, of USP Aspirin RS in the standard preparation , an ru and rs are the peak responses of the aspirin peaks obtained from

the Assay preparation and the Standard preparation respectively.