The Physical Analysis Expert Committee has revised the General Chapter Balances to correct a problem detected with the Repeatability test. USP Chapter 41 covers the minimum accuracy of weights and balances used to perform assays. The revised Repeatability test is as follows:
“Repeatability is satisfactory if two times the standard deviation of the weighed value, divided by
the nominal value of the weight usedthe desired smallest net weight, does not exceed 0.10 %”
The revised USP Chapter 41 was published July 2014 and can be accessed in the online forum of the USP, the USP PF. The printed version will be released shortly thereafter.
For further reading, see: Guide to Meeting New USP Changes