Determined by liquid chromatography.
Reference solution: Weigh accurately about 162.5 mg of Paracetamol reference standard, and 50 mg of Aceclofenac reference standard in 100 ml volumetric flask, dissolve in and dilute to the mark with mobile phase. Shake well and further dilute 2 ml to 25 ml with mobile phase. Shake well and filter through 0.45µm nylon filter.
Test preparation: Weigh accurately about equivalent to 165 mg of Paracetamol from crushed powder of 20 tablets in 100 ml volumetric flask, add 50 ml of mobile phase, sonicate for 5 minutes, cool to room temperature and dilute to the mark with mobile phase, filter. Shake well and further dilute 2 ml to 25 ml with mobile phase, shake well and filter through 0.45µm nylon filter.
Procedure: Inject separately standard and test preparation. Inject five replicate injection of working standard and two replicate injection of test preparation.RSD of replicate injection should not more than 2%. Calculate the assay of Paracetamol and Aceclofenac by comparison to peak area of standard preparation.
Mobile phase: – Methanol + Water + G.A.A. = 80: 20 +0.01ml; degas,
Column: – C-18, (150 x 4.6mm, 5µm);
Wavelength: – 280nm;
Flow rate: – 1.8ml per minute
Injection volume: – 20µl
Area of test Wt. of STD 2 100 25
——————-X————–X———–X———–X———–X Average. Wt. x potency of w.s.
Area of STD 100 25 test wt. 2
Acceptance criteria: 90.0%-110.0%