USP Chapter 41 Weighing Requirements on Balances in Pharamceutical QC
USP Chapter <41> weighing requirements are mandatory in a Pharmaceutical Quality Control (QC) laboratory, where weighing is a fundamental step in almost every workflow. Typically, weighing of a sample or standard is the first step in the analytical procedure, followed by dilution and subsequent analysis by techniques such as HPLC or qNMR. Any error in the weighing step has the potential to propagate through the whole analytical process, causing inaccuracy in the final result. To avoid this situation, the United States Pharmacopeia (USP) has set stringent requirements for balances that are used to weigh analytes for quantitative assessments. These requirements are designed to ensure that any uncertainty in weighing is small or even negligible within the analysis.
This white paper comprehensively explains the requirements of the 2019 versions of USP General Chapters <41> and <1251> and provides advice on how to put these requirements into practice. Weighing according to USP requirements will ensure that a consistently high quality of weighing results is achieved, and is applicable to all pharmaceutical QC activities globally, not just in those operating in the USA.
Ensure that your weighing processes are compliant with the current versions of USP General Chapters <41> and <1251>.
The mandatory General Chapter <41>, "Balances", describes three key requirements that a balance needs to fulfill when weighing analytes for quantitative measures: weighing should be performed on a calibrated balance that meets repeatability and accuracy requirements. This white paper will explain what that means and how to carry out acceptable repeatability and accuracy testing.
The informational General Chapter <1251>, "Weighing on an Analytical Balance", provides detailed guidance on the state-of-the-art strategy for qualification and operation of balances. Disseminating all the information of General Chapter <1251> would go beyond the scope of this white paper, so focus is given here to the dedicated topics of performance qualification and safety factor. These topics are selected as they reflect user routine testing of the equipment, which are crucial to ensuring that the instrument works continuously according to the requirements and is "fit for its intended purpose".