GWP® - The Weighing Standard: Why We Should Challenge the Established Way We Calibrate and Test Weighing Instruments

Abstract

In the pharmaceutical laboratory, weighing is only one step of a whole analysis chain in drug discovery and quality control; however it strongly influences the overall quality and integrity of the final result. Also in production, weighing is decisive to achieve batch uniformity and consistency, e.g. in dispensing or formulation processes. For the food industry, accurate weighing processes also act as an important contribution for two of its most demanding challenges: Increasing public health and consumer safety, and increasing productivity and competitiveness. The same or similar issues are also prevalent in other industries as the chemical, fragrance or automotive industry, and also apply for testing labs and companies focusing on contract research and manufacturing. Everywhere, accurate weighing is essential to ensure continuous adherence to predefined process requirements and to avoid a frequent source of Out of Specification results (OOS).This article introduces GWP®, the science-based global standard for efficient lifecycle management of weighing instruments. It consists of the selection of the appropriate weighing system based on the evaluation of the respective weighing process requirements, and provides scientific guidance to the user regarding calibration and testing during the instrument's lifecycle. Based primarily on the user’s weighing requirements and prevailing weighing risks, it provides a state-of-the-art strategy to reduce measurement errors and to ensure reproducibly accurate weighing results. The understanding of the particular weighing process requirements and important balance and scale properties as minimum weight is essential to select an appropriate weighing system in the framework of the design qualification. The performance qualification takes into account these requirements and risks to establish a specific routine testing scenario for the instrument. The higher the impact in case of inaccurate weighings, and the more stringent the weighing accuracy requirements are the more frequently calibration and user tests have to be carried out. However, for less risky and stringent applications, testing efforts can be reduced accordingly. Widespread misconceptions • specifically in respect to the definition of test procedures and the selection of appropriate weights for periodic performance verification • are critically analyzed. Based on scientific principles the user is guided on how to optimize his routine testing procedures and how to avoid unnecessary or even erroneous testing. Risk and life cycle management form an integrated part of the overall strategy of GWP® to bridge the gap between regulatory compliance, process quality, productivity and cost consciousness.