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USP General Chapter <41> Balances establishes the requirements for balances used for materials that are to be accurately weighed. Weighing must be done with a balance that is calibrated over the operating range and meets the defined requirements for Repeatability and Accuracy.

This proposal is based on the official version dated August 1, 2019. The proposal published in PF 49(5) [September-October 2023], has been cancelled and is being replaced by this new one.

The proposed changes gather comments received from stakeholders and are intended to align with Weighing on an Analytical Balance 〈1251〉 as well as the European Pharmacopoeia chapter “Balances for Analytical Purposes”.

In addition to formal changes, updates and additions were made in the following areas:

1. Introduce the relationship between calibration and performance checks within the life cycle approach to ensure fitness for purpose.
2. Include the concept of a risk-based approach with respect to the frequency of calibration and performance checks.
3. Add a new section on Calibration, clarifying its purpose and including considerations for uncertainty and frequency.
4. Introduce clarifications of compliance with respect to the Repeatability
5. Align the term minimum weightwith that in 〈1251〉 and in the European Pharmacopoeia, with regard to standard deviation. Include calculation examples.
6. Introduce text that differentiates the minimum weightfrom the smallest net weight.
7. Clarify criteria to ensure compliance with the required accuracy during performance test checks and calibration, including consideration of the uncertainty of the test weights.
8. Incorporate additional applicable references into the text.

Comments and observations on these drafts can be submitted until 30 November 2024.

USP General Chapter 〈1251〉 Weighing on an Analytical Balance is a guideline applicable to balances used in all analytical procedures. It provides information on installation and operational qualification (IQ/OQ), performance qualification and balance checks (routine testing), minimum weight, and balance operation.

This proposal is based on the version of the official chapter issued on May 1, 2018. The previous proposal, published in PF 49(5) [September-October 2023], has been cancelled and is being replaced by this new draft. Based on comments received from stakeholders and to align with Balances 〈41〉 as well as the European Pharmacopoeia chapter “Balances”, the following changes are proposed:

1. In the Introduction, clarify the group of instruments in which balances are included as per Analytical Instrument Qualification 〈1058〉 and its relationship with the analytical target profile described in Analytical Procedure Life Cycle 〈1220〉.
2. Add a new section, Principle, defining weight and units.
3. In Performance Qualification, the risk of the weighing application is explained with regard to the user’s quality management system in order to define the frequency and the type of performance qualification activities.
4. Discuss the frequency of each of the individual tests included, as well as the relationship between calibration and verification.
5. Delete the section Balance Checks and integrate it into Performance Qualification.
6. Simplify the definition of minimum weight and add clarifications about the tare vessel as well as examples to address frequently asked questions.
7. Introduce a safety factor that addresses critical performance changes of the balance during routine usage.
8. Add a Glossary to clarify the use of specific terms.
9. Add Additional Information to ensure alignment of concepts and terminology.

SOURCES:

Pharmacopeial Forum (PF) | USP-NF (uspnf.com)