Measurement uncertainty arising from sampling of environmental samples

Area of Science:

• Environmental Science
• Analytical Chemistry
• Metrology

Background:

• The 2017 ISO/IEC 17025 revision mandates the evaluation of sampling uncertainty.
• Accurate uncertainty budgets are crucial for reliable environmental measurements.

Purpose of the Study:

• To evaluate the contribution of sampling procedures to the total uncertainty budget in high-resolution gamma-ray spectrometry.
• To assess sampling uncertainty for environmental soil, tap water, and aerosol filter samples.

Main Methods:

• Statistical analysis of measurements from replicate samples.
• Calculation of sampling uncertainty based on standard deviation and combined uncertainty budget.
• Application to high-resolution gamma-ray spectrometry data.

Main Results:

• Sampling uncertainty was approximately 5% (k=1) for soil samples with low heterogeneity.
• Sampling uncertainty ranged from 30-40% (k=1) for aerosol filter samples.
• Sampling uncertainty was not significant for consecutively collected tap water samples.

Conclusions:

• Sampling uncertainty is a critical component of the total uncertainty budget for certain environmental matrices.
• The significance of sampling uncertainty varies greatly depending on the sample type and its heterogeneity.
• The study provides essential data for improving uncertainty evaluations in environmental gamma-ray spectrometry.