Expert: John Franceschini - 2/20/2010

Question
Dear Mr. John Franceschini,
I am working as a Quality Assurance Executive in one of the Pharmaceutical Company.
My doubt is regarding the Analysis of Raw Materials.
   What is the difference between Assay & Potency of a Raw material?
   What does it mean if assay is more than 100% on anhydrous or solvent free basis?
   Why anhydrous and dried based assays are even more than 100%?

   If have one formulae for Dispensing of raw material required for a batch.

    Standard Quantity required if assay is 100% and LOD is 0%          x    100     x                   100
--------------------------------------------------------------------------                                  ------------------------
                                      Assay                                                                                                        (100 - LOD)

   If a Raw material assay is reported as 102% on dried basis, and LOD is reported as 0.5%.
Than in the above formulae Assay shall be taken as 102 or 100?

Please Clarify

Answer
Im sorry for the delay- I naswered this question last week but must not have sent it correctly

Assay is the analytical results of a said parameter- potency is the effectiveness of the parameter. They may be the same in some cases.

If the assay is more than 100% this is the analytical error of the procedure- it should be corrected back to 100% where possible

The anhydrous or solvent free basis has the volatiles removed- hence it could give an answer more than 100% if there is an error
Alway use 100% to calculate the required amount of material