USP <41> Minimum Net Weight

Discussions about sample preparation: extraction, cleanup, derivatization, etc.

4 posts Page 1 of 1
Hi all,

I have a question about USP <41> and the minimum weighing criteria. The balances usually say that the minimum net weight is x; therefore weights below x are not accurate and would be in violation of my SOPs. If y is greater than x, mm I able to get around the minimum weight by putting in a container with weight y+x and then subtract out y? y+x and y are both greater than x.
In a word, NO!

Let's say you have a 4 place balance. Even if your RSD for replicate 50mg weights is 0, the 0.41 rule limits your accurate weight limit to >85mg.

Weighing less than that in a 2g weigh boat makes no difference, your net weight has to be at least 85mg to possible be "accurate" per the USP.
Thanks,
DR
Image
dchau503 wrote:
Hi all,

I have a question about USP <41> and the minimum weighing criteria. The balances usually say that the minimum net weight is x; therefore weights below x are not accurate and would be in violation of my SOPs. If y is greater than x, mm I able to get around the minimum weight by putting in a container with weight y+x and then subtract out y? y+x and y are both greater than x.


Somewhere in the archives is a thread about this exact subject, and it goes on and on for about 20 pages. The answer is short and simple though; NO.
Peter Apps
I agree with Peter! You cannot squirm your way out of compliance with the regulations. Buy an ultrabalance!
4 posts Page 1 of 1

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