Bioequivalence and Bioavailability Forum

Hi everyone!

In our lab when we prepare stock solution we weigh an approximate quantity of standard and add an equivalent amount of solvent in it. For example, we weigh about 10.3 mg of reference standard (when trying to weigh 10.00mg )and add 10.3 ml of solvent with a calibrated pipette to prepare a 1mg/ml solution. From that solution we prepare our calibrators.

However, an auditor raised the objection that in our case the final volume of the solution would change since the volume occupied by solute also adds to the final volume and hence the strength we finally get is different from what we intended. They suggested using a volumetric flask (say 10ml), weigh an approximate quantity (say 10.3mg as in our case) but make up volume to 10ml so final concentration is 10.03mg/ml which should be used for preparation of further dilutions.

Please let me know if this difference in the method of solution preparation is significant enough to invalidate our previously done studies?

Secondly, which method is more practical to work with?

Regards