The U.S. Pharmacopeial Convention (USP) is a scientific nonprofit organization that sets globally-recognized standards for quality of medicines, food ingredients and dietary supplements developed and manufactured for human consumption. The USP’s guidelines recently underwent major revisions, and in December 2013, updates to Chapter 41 and 1251, which have an impact on weighing technology went into effect.
Chapter 41 focuses on the “requirement for balances used to weigh analytes for quantitative measures.” Balance repeatability and accuracy was once an area in which there was once much ambiguity, and the updates attempt to better define the parameters to be used when determining the appropriate minimum weight and operating range. The updates to Chapter 41 include increasing the number of balance tests from one to two, changing expansion factor from 3 to 2 and increasing the limit of repeatability test from ≤ 0.1% to ≤ 0.10% to reduce errors caused by rounding. Additionally, Chapter 41 addresses calibration weights for the first time, indicating that test weights should be between 5% and 100% of balance capacity.
Chapter 1251 has undergone major revisions focusing on balance qualification and operation. Among the new additions is a clear definition of minimum weight, which refers to the sample weight, and not tare or gross weight. Chapter 1251 also defines protocol for balance testing frequency, in order to ensure necessary testing is conducted and unnecessary testing can be eliminated, helping to improve laboratory efficiency. For example, a daily balance check, which is typical in many laboratories, is not actually a requirement. Instead, the type and frequency of balance checks should be determined by the risk and process tolerance of the application. Performing the right tests at the right intervals will ensure quality results and can potentially save time and money by eliminating unnecessary testing!
While the criteria listed in Chapter 41 is enforceable, Chapter 1251 includes recommendations for optimal results.
Defining guidelines and requirements for accurate and precise weighing from the outset will help assure accuracy during every phase of a project. OHAUS portfolio includes multiple balances, including the Explorer and Adventurer Pro, that conform to these guidelines and can assure that all weight determination in pharmaceutical compounding applications meet the criteria set forth by the USP. Click here to see the complete article courtesy of Ohaus.