Summary of Changes to the USP Chapter 41

Chapter 41

OldNew

Area of application

  • Applies only to assays
  • Determination of minimum sample weight
  • Applies only to accurate measurements
  • Determination of a balance’s operating range


RepeatabilityOldNew
Repeatability tolerance0.1 (49)%0.10%
Expansion factor K32
Number of weighing values for the repeatability test1010
Acceptance criterion3 x std. dev. / m ≤ 0.1%2 x std. dev. / m ≤ 0.10%
Smallest possible sample weight | Lowest starting point1,000 d820 d


AccuracyOldNew
ToleranceNA≤ 0.10%
Reference weightNABetween 5% and 100 % of the balance’s operating range