VaMPIS - Validation of Measurement Procedures that Include Sampling

Significance of the Topic

Accurate analytical measurements require not only validated laboratory procedures but also reliable sampling processes. Ignoring primary sampling can underestimate uncertainty and compromise data quality. Integrating sampling into method validation ensures measurement results are truly representative and decision-ready for regulatory compliance, quality control and research.

Objectives and Study Overview

The VaMPIS (Validation of Measurement Procedures that Include Sampling) guidance aims to extend traditional method validation by including primary sampling. It unifies sampling and analytical procedures into a single measurement workflow. Users can apply the approach either simultaneously—validating sampling and analysis together—or sequentially—where an existing analytical method is reassessed within the broader measurement context.

Methodology and Instrumentation Used

The core metric in VaMPIS is measurement uncertainty (MU), which integrates random and systematic effects from both sampling and analysis. Key elements include:

• Duplicate Method: At least eight independent primary sampling events produce duplicate samples, each analysed in duplicate.
• ANOVA Evaluation: Analysis of variance partitions uncertainty into sampling variability and analytical repeatability, incorporating bias terms where data permit.
• Target Uncertainty: A predefined MU goal (set by regulators or via methods such as the Optimum Uncertainty technique) guides fitness-for-purpose assessments.
• Workflow Steps: Eleven steps—ranging from measurand specification through MU estimation to iterative method refinement—provide a clear validation pathway.

Instrumentation examples include portable X-ray fluorescence (pXRF) for in situ soil measurements and standard laboratory equipment for ex situ chemical analysis of composite plant samples.

Main Findings and Discussion

VaMPIS demonstrates that incorporating sampling uncertainty into overall MU leads to more realistic performance assessments. The guidance’s flowchart outlines decision points: if actual MU exceeds the target, users decide whether to enhance sampling or analytical procedures based on their respective contributions to uncertainty and cost. Case studies illustrate application:

• Ex situ validation of nitrate determination in composite lettuce samples.
• In situ assessment of lead in soil using pXRF without sample removal.

Integrated measurement quality control (IMQC) is recommended post-validation to maintain performance and encourage collaboration between laboratory analysts and field sampling teams.

Benefits and Practical Applications

Implementing VaMPIS offers several advantages:

• Comprehensive uncertainty evaluation enhances confidence in results used for regulatory thresholds.
• Structured validation workflow improves resource allocation by identifying whether sampling or analysis drives uncertainty.
• Facilitates harmonisation of field and laboratory practices, supporting cross-disciplinary quality assurance.

Future Trends and Potential Applications

As measurement technologies evolve, VaMPIS may integrate digital sampling records, real-time uncertainty monitoring and advanced statistical tools. Wider adoption of in situ techniques and remote sensing will drive the need for unified validation frameworks. Collaborative platforms can enhance communication between sampling teams and analytical laboratories, fostering continuous improvement in measurement quality.

Conclusion

The VaMPIS guidance fills a critical gap by embedding sampling into method validation through a unified uncertainty framework. Its structured approach and practical examples enable users to achieve fitness for purpose and support reliable decision-making across analytical chemistry applications.

References

1. Ramsey M. H., Ellison S. L. R., Rostron P. (eds.). Eurachem/EUROLAB/CITAC/Nordtest/AMC Guide: Measurement Uncertainty Arising from Sampling (2nd ed. 2019).
2. Cantwell H. (ed.). Eurachem Guide: The Fitness for Purpose of Analytical Methods – A Laboratory Guide to Method Validation and Related Topics (3rd ed. 2025).
3. Ramsey M. H., Rostron P. D., Raposo F. C. (eds.). Eurachem/EUROLAB/CITAC/Nordtest/AMC Guide: Validation of Measurement Procedures that Include Sampling (2024).