Mettler-Toledo Release: New Resource Helps Ensure Weighing Operations Are USP Compliant

Published: Jan 30, 2017

Ensuring compliance with revised United States Pharmacopeia (USP) chapters 41 and 1251 on weighing is a topic that still requires clarification for many pharmaceutical manufacturers worldwide. Read "Compliance with USP General Chapters 41 and 1251 on Weighing", from METTLER TOLEDO's free online laboratory expertise library to learn what is currently required for USP 41 and 1251 and what is no longer required.

Greifensee, Switzerland— January 30th, 2017— The major revisions to USP General Chapters 41 and 1251 (official since 2013-2014) had implications on the quality management of balances in the laboratory. The aim was to clarify and simplify previous versions and to reflect state-of-the-art weighing practices in order to help US pharmaceutical manufacturers and suppliers ensure weighing accuracy and eliminate unnecessary balance test procedures. However, many pharmaceutical companies still seem to be unclear or unaware of the changes and how to implement them correctly.

The mandatory General Chapter 41 states that accurate weighing must be performed using a calibrated balance. Repeatability and accuracy requirements have been updated with changes to the acceptance limits and permissible test weights. General Chapter 1251 provides additional clarification on the new procedures and extends the scope to any balance used for an analytical procedure. Major revisions have been made on balance qualification and operation, including emphasis of the importance of "minimum weight". A daily balance check, typical in the pharmaceutical industry, is not described anymore. In fact, balance performance verification should be carried out using a risk-based approach.

The "USP Revisions" compendium describes the changes in an easy-to-digest format. It offers a brief, easy-to-understand instructional video—split into three parts—and detailed web training on the current requirements of USP 41 and 1251 to help ensure correct implementation of both mandatory and recommended process changes . A white paper describing the new weighing requirements and factors that affect measurement uncertainty is also available to download for free.

The Laboratory Expertise Library itself is a collaborative space which offers a wealth of free information and advice on a range of critical laboratory issues. The topics are carefully selected to focus on the daily concerns of laboratory managers and personnel, and include issues such as electrostatic effects on weighing, regulatory compliance, calibration, and sample preparation. In-depth knowledge and expert advice is shared in a helpful and easily accessible format, with basic introductory or advanced information available. New topics are added regularly.

To propose a topic to be included in this library in the future, please contact METTLER TOLEDO.


METTLER TOLEDO is a leading global supplier of precision instruments and services. The Company is the world’s largest manufacturer and marketer of weighing instruments for use in laboratory, industrial and food retailing applications. METTLER TOLEDO also holds top-three market positions in several related analytical instruments and is a leading provider of automated chemistry systems used in drug and chemical compound discovery and development. In addition, the Company is the world’s largest manufacturer and marketer of metal detection and other end-of-line inspection systems used in production and packaging and holds a leading position in certain process analytics applications. Additional information about METTLER TOLEDO can be found at

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