CAP interlaboratory survey of analytic balances

Area of Science:

• Analytical Chemistry
• Metrology

Background:

• Accurate weighing is fundamental in analytical chemistry and metrology.
• Variability in analytic balance performance can impact experimental results.

Purpose of the Study:

• To assess the performance and accuracy of analytic balances across multiple laboratories.
• To quantify the typical error margins for weighing small samples.

Main Methods:

• An interlaboratory survey was conducted.
• Aluminum oxide spheres (approx. 525 mg) were used as test samples.
• Data from 83 participating laboratories were analyzed.

Main Results:

• 82 of 83 laboratories completed the survey.
• Results indicate that for 525 mg samples, errors typically do not exceed +/-0.3% in 95% of weighings (19/20).
• Errors are expected not to exceed +/-0.4% in 99.7% of weighings (997/1000).

Conclusions:

• Analytic balances demonstrate high accuracy and reliability at the 525 mg weight level.
• The survey provides statistical data on expected weighing error margins.
• Understanding variance components is crucial for maintaining measurement precision.