Chromatography Forum

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.

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.

I agree with Peter! You cannot squirm your way out of compliance with the regulations. Buy an ultrabalance!