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Debbie ★ India, 2009-05-09 20:56 (6258 d 10:42 ago) Posting: # 3668 Views: 2,947 |
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Hello, could any one provide the clarification on the potency calculation of liquid working standard, i have a liquid working standard with the assay value of 99.2%. i have weighed the 50.012 mg of the above standard and dissolved in 5 ml of the diluent.(for preparation of stock solution) for calculating the concnetration of the stock solution, do i just consider the weight and calculate the concentration by the following formula: calculated concentration= (amount weighed/volume in ml)*(potency/100)*1000. or as it is the liquid, the density of the solution needs to be considered (for this the density is 0.85 as per COA). Regards, Debbie, |
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NewInPK ☆ 2009-05-13 03:32 (6255 d 04:05 ago) @ Debbie Posting: # 3681 Views: 2,240 |
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Hi Debbie, If you want to have mass/volume units, and since you have already weighted the standard, you don't need to use the density. Your formula above will lead to a concentration of 9920 mcg/mL (if you keep 3 significant digits, which would in fact depend on the precision of the 5 mL measurement, but that would be the topic of another post). You would use the density only if you want to convert back to volume/volume units, but that is less common. On the other hand, if weighing is not very convenient, you could measure an exact volume with a calibrated pipette, then using the density you can calculate to mass and go from there. |
Ing. Helmut Schütz