I have a problem in assay calculation. where I analyse hard gelatin capsule of Amoxicillin. the capsule contains 266 mg of Amoxicillin Trihydrate equivlaent to 250mg of amoxicillin. I use the following equation.
mg/cap = A t x W s( mg) x Dfu x P x Av. Fill Wt. of cap.
A s x Dfs x W t (mg) x 100
where
A t : the response of test solution.
A s : the response of standard solution.
Dfu : the dilution factor of test solution.
Dfs : the dilution factor of standard solution.
W t & W s : the weigh of Test and standard respectively.
P : is the purity of amoxicillin standard.( here is the problem)
where I have two assay of Amoxicillin working standard one is AS SUCH ( 85.9%) and ON DRY BASIS 98.8%) my question here when I use ON DRY BASIS potency should I have the result of mg/cap as amoxicillin base or WHAT???
Provided that the USP does not recommend drying the standard of Amoxicillin trihydrate).
Please can you help