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Good Weighing Practice

Good Laboratory Practice (GLP) and what it means for Weighing

What is Good Laboratory Practice (GLP)?

Good Laboratory Practice, also known as GLP, was first introduced in New Zealand and Denmark in 1972. It is a quality assurance system used by laboratories and organisations to ensure the uniformity, consistency and reliability of non-clinical study and test data.

GLP applies to non-clinical studies regulated by government agencies that are conducted for the assessment of the safety or efficacy of products in development for humans, animals and the environment. The term GLP is most commonly associated with the pharmaceutical industry and the required non-clinical animal testing that must be performed prior to approval of new drug products. However, GLP also applies to other applications such colour additives, food additives, food contamination limits, food packaging, and medical devices.

Good Weighing Practice

Increasing attention is being directed towards good weighing practice in laboratories because it is one of the most commonly performed tasks. Focus on the accuracy and suitability of the weighing balance and the various elements that influence the weighing process is crucial. Therefore, GLP compliance is a frequent selling point for laboratory balances such as the ones produced by Precisa.

GLP regulations for the weighing process include the following factors:

  • SUITABILITY: the weighing balance must have the suitable readability and capacity for the object being weighed. For example, an analytical balance with a readability of 0.0001g would be unsuitable for the weighing of a rabbit.
  • RESOURCES: The equipment must be in proper working order (i.e. calibrated and well maintained) and the researcher’s qualifications and training should be documented.
  • RULES: Weighing tests should be conducted using correct written protocols providing the design and timeframe used.
  • RESULTS: The final report must include an account of the way the study was performed and the scientific interpretation of the data.

Weighing Balance Calibration

The calibration of a balance is a highly important regulatory requirement for laboratories looking to comply with Good Laboratory Practices. The required frequency of calibrations is defined as part of the standard operating procedures and documentation of calibrations must be kept.

The process of calibration eliminates errors of the built-in weights by comparing an unknown object to a known mass standard.

At Precisa, we offer bespoke engineer visits providing basic calibration services, UKAS and ISO level balance calibration or more specific tailoring to suit a specific requirement.  Your accreditation or certification body should provide information regarding the type of calibration service required for your balance. Find out more about the importance of calibration and the calibration services we provide.

Good Weighing Practice

Factors Influencing Weighing Results

Good laboratory practice involves the elimination of the following various external factors that can affect weighing measurements and compromise the accuracy of results.

  • VIBRATIONS: Balances should be set up on a stable and level surface with no vibrations to prevent fluctuations in readings due to shifts in the balance level.
  • TEMPERATURE: Balances should be kept in a temperature controlled environment, out of direct sunlight and the direct line of ventilation.
  • OBJECT HANDLING: Gloves should be worn and forceps used when handling small weights to prevent any fluctuations to their weight.
  • OPERATION: Balances should be operated carefully to provide consistency in repeated measurements. For example, weights should be placed gently at the centre of the weighing pan and care should be taken not to shock load the balance.
  • SUFFICIENT POWER: Balances must have had a constant power flow of 30 minutes to 1 hour in order to ensure that the electrical components have reached the correct thermal equilibrium.
  • CLEANING & STORAGE: Balances must be stored away from dust or liquids and kept clean to avoid contamination which can compromise accuracy.

To find out more read our Guide to Weighing Balance Accuracy.

Get in Touch

If you would like to find out more about good laboratory practice for weighing, please don’t hesitate to get in touch with a member of our team today.

We have a wide range of precision and analytical balances in compliance with GLP which can be viewed on our website.

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