Identifying Unknown Sources of Error in Your Weighing Process
Analytical balances are at the heart of virtually all quantitative analyses in both regulated and unregulated laboratories. Accurate weighing and data integrity are essential in the preparation of analytical reference solutions, reagents and buffers, as well as in taking aliquots of samples for analysis. Errors in these processes can have a profound impact on data integrity and product quality.
Weighing is one of the most common, yet critical and time consuming, tasks undertaken in the laboratory. Any factor that affects weighing accuracy can negatively influence the results of a whole analysis, meaning that weighing the right way is crucial.
Advances in electronics have considerably simplified the operation of balances, reducing weighing times. Moreover, the touchscreen digital display makes operation of the balance intuitive. However, this apparent ease of use can lead to insufficient care being taken to avoid the negative influence of multiple factors on the analytical results.
External influences are defined as physical effects that are measurable for all laboratory balances and include:
- Electrostatic forces
- Environmental vibrations
- Effects of magnetism
- Moisture uptake
In addition, certain sample characteristics – such as the evaporation of liquids, or hygroscopic/hydrophobic solid materials gaining or losing weight – can also be mistaken for external influences.
These documents discuss the most common factors affecting weighing accuracy, and explain the basic rules of weighing the right way with laboratory balances. They cover choosing the optimal balance location and proper operation of this sensitive instrument, as well as analyzing possible external influences and their effects.