How to calculate the percentage stated content of sample Paracetamol tablet?
- 20 tablets of Paracetamol (500mg) taken and crushed into powdered form.
- Tablet powder containing 0 .61g is shaken with 300ml of .05M acetic acid.
- The extract is then made up to 500ml with 0.05M acetic acid.
- The absorbance of the diluted extract is measured at 271nm.
- The A (1%, 1cm) value at 257 is 715.
Weight of 20 tablets = 11.49g
Powder taken (equivalent) = 11.49/20 = 0.57
Expected Content in tablet powder taken:
= wt. of powder taken/wt. of 20 tab x stated content x No. of tablets.
=0.57/11.49 x 500 x 20
Dilution factor = 50
Calculated Content in tablet powder taken:
Concentration in diluted tablet extract = A/A1%, 1cm
=1.462/715 =0.002g/100ml =2.04mg/100ml
Concentration in original tablet extracts = 2.04 x D.F =2.04 x 50 =102mg/100ml
Volume of original extract = 500ml
So, amount in original extract= 102 x 5= 510mg
Percentage of stated content = Calculated/Expected x 100
=510/496.08 x 100 =102%
So, the percentage stated content of sample Paracetamol tablet is 102%
Abid Ali @abidaliphm
Doctor of Pharmacy