[PrinceFaz]

Assay of Frusemide tablets

Tablet powder containing ca. 0.25g frusemide shaken with 300ml of 0.1M NaOH
Extract made up to 500 ml with 0.1M NaOH
Extract filtered and 5ml made up to 250ml with 0.1MnaOH
Absorbance of diluted extract measured at 271 nm
A(1%, 1cm) value at 271 = 580 in basic solution


Calculate the % stated content of frusemide in tablets 

Stated content = 40mg
Weight of 20 tablets = 1.656g
Weight of powder taken for assay = 0.5195g
Absorbance = 0.596

The answer is 102% which lies within the 5% BP Regulations. If someone can show me the best possible way step by step way of working things out. Would be much appreciated. At the moment i am uneasy with the calculation, not that confident. Thanks

[JGK]

Assay of Frusemide tablets

Tablet powder containing ca. 0.25g frusemide shaken with 300ml of 0.1M NaOH
Extract made up to 500 ml with 0.1M NaOH
Extract filtered and 5ml made up to 250ml with 0.1MnaOH
Absorbance of diluted extract measured at 271 nm
A(1%, 1cm) value at 271 = 580 in basic solution


Calculate the % stated content of frusemide in tablets 

Stated content = 40mg
Weight of 20 tablets = 1.656g
Weight of powder taken for assay = 0.5195g
Absorbance = 0.596

The answer is 102% which lies within the 5% BP Regulations. If someone can show me the best possible way step by step way of working things out. Would be much appreciated. At the moment i am uneasy with the calculation, not that confident. Thanks

Absorbance (Abs of final extract) = 0.596
Equivalent to (abs/A) = 1.028 x 10-3 % in final extract solution
Multiply by 50 (covers dilution factor from original extract) = 0.0514% (w/v) in original extract
(1% w/v =1 g/ 100mL =10 mg/mL)
Original extract = 0.514 mg/mL or 257 mg in weighed sample.
(257/0.5195)* 1.656 = 819.23 mg in total sample (20 tablets)
=40.96 mg/tablet = 102.4% of specification