<p><strong>Validation of analytical methods (i.e. procedures) usually excludes the primary sampling, but this is now widely recognised as the first step in the measurement procedure [1] (Fig.1). Validation of the whole measurement procedure therefore requires consideration of a performance characteristic that reflects the quality of all of the steps (including sampling and physical sample preparation). The uncertainty of the final measurement value is that key characteristic that unifies this whole measurement procedure and enables its validation, particularly when supported by performance characteristics that have an established role in the validation of an analytical procedure as a standalone activity [2]. This leaflet summarises the new Eurachem/CITAC guidance on the Validation of Measurement Procedures that Include Sampling (VaMPIS) [3]. It can be applied to the whole measurement process either simultaneously, where the sampling and analytical procedures are validated as a unified measurement procedure, or sequentially when the analytical procedure has previously been validated in isolation.</strong></p><h4><strong>In situ and ex situ measurement</strong></h4><p>There are now many <i><strong>in situ</strong></i> measurement techniques (e.g. portable XRF in Fig. 1c), where the measurement is taken directly from the sampling target, without the need to extract a physical sample. This <strong>new mode of measurement </strong>highlights the need for an integrated approach to the definition of the measurement process so that it includes sampling. This approach is also equally applicable to the traditional mode of ex situ measurement (Fig. 1b) of a physical sample extracted from a sampling target (Fig. 1a). Both modes require the primary sampling to be included within the measurement procedure, its validation, and in the estimation of measurement uncertainty.</p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Eurachem_Figure_1_Representation_of_the_whole_measurement_process_7e63297705.jpg" alt="Eurachem: Figure 1. Representation of the whole measurement process that requires validation. In the ex situ mode this includes the two steps of (a) primary sampling (in this case of a bay of lettuce heads) followed by (b) chemical analysis. In in situ mode this usually requires just one step (c) both sampling and analysis within the same measurement process (in this case in situ pXRF on an area of soil)." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Eurachem_Figure_1_Representation_of_the_whole_measurement_process_7e63297705.jpg 172w," sizes="100vw" width="857" height="778"></p><h4><strong>How to apply VaMPIS</strong></h4><p>The only parameter of a measurement procedure that can effectively integrate the effects on data quality from all of the steps in the procedure (including sampling) is the <strong>measurement uncertainty.</strong> This uncertainty is stated within the final measurement result. It allows the user of that result to assess the effects of both random and systematic effects arising at every stage of the measurement procedure on decisions that are to be made using that result (e.g. compliance of a batch of material with a regulatory threshold). The VaMPIS approach therefore uses the uncertainty of the measurement value to judge the <strong>fitness for purpose</strong> (and hence validity) of the whole measurement procedure by comparing it with a ‘target’ uncertainty. It is <strong>essential that the target uncertainty should also include the contribution from sampling</strong>, and it can either be set by an external body (e.g. a regulator) or, if that is not available, by the user, using a technique such as the <strong>Optimum Uncertainty method</strong> ([3] Appendix B). <strong>Worked examples</strong> of validation are given where the whole measurement procedure is applied, either ex situ (Appendix A1: Nitrate in extracted composite samples of lettuce, Fig. 1a) or in situ (A2: Pb in soil by pXRF without removal of physical samples, Fig. 1c). There are eleven broad steps for the application of VaMPIS (Fig. 2). Measurement uncertainty is generally estimated using the <strong>Duplicate Method</strong> in which duplicate primary samples are taken from at least eight sampling targets by an independent reinterpretation of the sampling procedure. Both duplicate samples are then analysed in duplicate. The measurement uncertainty, and its main components from sampling and analysis (as repeatability), are estimated by applying ANOVA to the resultant measurement values, and also including analytical bias and sampling bias where possible [1]. The <strong>fitness for purpose of the procedure</strong> is judged by comparing the estimated measurement uncertainty against a value of target uncertainty set for that particular purpose [3].</p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Eurachem_Figure_2_Flow_chart_for_Va_MPIS_application_0371d52580.jpg" alt="Eurachem: Figure 2. Flow chart for VaMPIS application" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Eurachem_Figure_2_Flow_chart_for_Va_MPIS_application_0371d52580.jpg 127w," sizes="100vw" width="735" height="898"></p><p>There are <strong>planning steps</strong> followed by <strong>implementation steps</strong>. The measurement uncertainty (MU) and its component arising from sampling (UfS) are usually estimated using the Duplicate Method followed by Analysis of Variance (ANOVA) [1]. The <strong>decision</strong> on whether the measurement procedure (MP) is fit for purpose (FFP) is based upon comparing the actual MU against the target MU. If not FFP, the decision on whether to improve the sampling procedure (SP) or the analytical procedure (AP) depends on their respective contributions to both the MU and the measurement cost. In the sequential approach to VaMPIS, the FFP of the AP, that has been previously validated in isolation, is checked to see if it is still FFP within this whole MP. If the MU from the analytical procedure needs to be improved, the most appropriate of the traditional performance characteristics [2] need to be modified to that end. (AQC is Analytical Quality Control.)</p><p>The VaMPIS guide [3] also includes a discussion of the role of ongoing quality control of the whole measurement procedure (integrated measurement quality control, IMQC) to ensure ongoing quality compliance after the initial validation. One major challenge for implementation that is also discussed, is to ensure effective communication and cooperation between the laboratory staff and the oftendifferent organisation that takes the samples.</p><blockquote><p>Produced by the Joint Technical Group on VaMPIS with representatives from the Eurachem and AMC Sampling Uncertainty and Eurachem Method Validation Working Groups, as well as from CITAC &amp; Nordtest. First English edition, [April 2025], <a href="www.eurachem.org"><strong>www.eurachem.org</strong></a></p></blockquote>

VaMPIS - Validation of Measurement Procedures that Include Sampling

<p><strong>Eurachem and CITAC welcome analysts interested in the evaluation of chemical analysis uncertainty and in how to use this information in results interpretation. The Eurachem Week 2026 will begin with a training course on “Evaluation of the measurement uncertainty from in-house precision and recovery data” scheduled for Sunday, 10 May 2026. A two-days workshop on “Quality in Analytical Measurements: Uncertainty Evaluation and Results Interpretation” open to all interested participants will take place from 11 to 12 May 2026. On 13 May 2026, the Eurachem Working Groups will convene, followed by the Eurachem General Assembly, which will bring together the Executive and national delegates on 14 and 15 May. Both Working Group Meetings and the General Assembly are restricted to their members.</strong></p><p>The results of qualitative and quantitative chemical analyses should have an acceptable uncertainty, which should ideally be reported and considered in results interpretation.</p><p>For many analytical applications, simplified uncertainty evaluations can determine uncertainty values that meet the defined requirements for this parameter. The workshop will focus on the key technical challenges involved in practical evaluations of measurement uncertainty based on precision and recovery data gathered during in-house method validation and quality control. There will be a discussion of how to model the variation of the measurement uncertainty within the analytical range and how to handle divergent recovery values from the analysis of various reference materials. A session on the use of measurement uncertainty in conformity assessment will explore how the risk of false conformity decisions can be managed.</p><blockquote><h5><strong>New Eurachem guidance on using in-house precision and recovery data will be discussed at the workshop.</strong></h5></blockquote><p>Topics will also include the validation and uncertainty evaluation for qualitative analyses with particular attention to current accreditation requirements for these types of analysis. The last session of the workshop will be dedicated to the evaluation of measurement uncertainty arising from sampling and using it to judge the fitness for purpose, and hence validation, of measurement procedures that include sampling. Four sessions of the workshop will include engaging breakout sessions where participants will have the chance to share their views about challenging aspects of the analytical work. Participants are invited to propose posters and oral communications on session topics or any other relevant topic for analytical chemists or stakeholders of the analytical work.</p><h3><strong>Registration</strong></h3><blockquote><p class="cke-user_style-important"><strong>👉</strong><a target="_blank" rel="noopener noreferrer" href="https://conferences.chemistry.pt/register/eurachem2026"><strong>Register here for the workshop</strong></a></p></blockquote><h4><strong>Registration Fees</strong></h4><h5><strong>Early bird (EUR) - Until April 15th</strong></h5><ul><li><strong>Workshop: Regular participant (11 &amp; 12 May 2026): </strong>400 EUR</li><li><strong>Workshop: Student (11 &amp; 12 May 2026): </strong>250 EUR</li><li><strong>Eurachem Working Group<sup>1</sup> (13 May 2026):</strong> 75</li><li><strong>General Assembly<sup>2</sup> (14 &amp; 15 May 2026): </strong>250</li><li><strong>Training On Uncertainty Evaluation<sup>3</sup> (10 May 2026):</strong> 150</li></ul><h5><strong>After April 15th</strong></h5><ul><li><strong>Workshop: Regular participant (11 &amp; 12 May 2026): </strong>450 EUR</li><li><strong>Workshop: Student (11 &amp; 12 May 2026):</strong> 300 EUR</li><li><strong>Eurachem Working Group<sup>1</sup> (13 May 2026): </strong>100</li><li><strong>General Assembly<sup>2</sup> (14 &amp; 15 May 2026):</strong> 300</li><li><strong>Training On Uncertainty Evaluation<sup>3</sup> (10 May 2026): </strong>200</li></ul><blockquote><p>§ - <strong>50 EUR reduction for members of Eurachem</strong>, CITAC, SPQ, RELACRE, ForMEQ and SPMet at the workshop.</p><p>10% reduction for organisations that registered more than one participant.</p><p><sup>1 </sup>- Working group members</p><p><sup>2</sup> - Eurachem members</p><p><sup>3</sup> - 50% reduction for workshop participants</p></blockquote><h3><strong>Workshop</strong></h3><h4><strong>Eurachem/CITAC Workshop on Quality in Analytical Measurements:</strong></h4><h5><strong>Uncertainty Evaluation and Results Interpretation</strong></h5><p>The results of qualitative and quantitative chemical analyses should have an acceptable uncertainty, which should ideally be reported and considered in results interpretation. For many analytical applications, simplified uncertainty evaluations can determine uncertainty values meeting defined requirements for this parameter. The workshop will focus on the key technical challenges involved in practical evaluations of measurement uncertainty based on precision and recovery data gathered during in-house method validation. It will be discussed how to model the variation of the measurement uncertainty within the analytical range and how to handle divergent recovery values from the analysis of various reference materials. A session on the use of measurement uncertainty in conformity assessment will explore how the risk of false conformity decisions can be managed.</p><p>Topics will also include the validation and uncertainty evaluation of qualitative analyses with particular attention to current accreditation requirements for these types of analysis. The last session of the workshop will be dedicated to the evaluation of measurement uncertainty arising from sampling and using it to judge the fitness for purpose, and hence validation, of measurement procedures that include sampling.</p><p>Four sessions of the workshop will include engaging breakout sessions where participants will have the chance to share their views about challenging aspects of the analytical work. Participants are invited to propose posters and oral communications on session topics or any other relevant topic for analytical chemists or stakeholders of the analytical work.</p><h3><strong>Training Course</strong></h3><h4><strong>Evaluation of the measurement uncertainty from in-house precision and recovery data</strong></h4><ul><li>10 May 2026</li></ul><p>A course on the fundamentals of the evaluation of the measurement uncertainty from in-house precision and recovery data will be held on Sunday, 10 May 2026. This training is targeted for analysts with a basic understanding of the measurement uncertainty concept, how uncertainty components propagate, and how the combined uncertainty is expanded. Following the morning presentation of the theory of uncertainty evaluation, the afternoon will be dedicated to applying the theory to real-world cases. Trainees should have basic skills in using Microsoft Excel spreadsheets and bring a laptop with Microsoft Excel to complete the exercises. The interaction between trainers and trainees will be promoted to guarantee learning efficiency.</p><h5><strong>Trainers:</strong></h5><ul><li>Ricardo Bettencourt da Silva, Faculdade de Ciências da Universidade de Lisboa, Portugal (rjsilva@ciencias.ulisboa.pt)</li><li>Stephen L. R. Ellison - UK National Measurement Laboratory (NML) hosted at LGC, United Kingdom</li><li>Vicki Barwick - UK National Measurement Laboratory (NML) hosted at LGC, United Kingdom</li></ul><h4><strong>Agenda</strong></h4><h5><strong>8:00 Registration</strong></h5><h5><strong>9:00 Opening</strong></h5><h5><strong>9:05 Identifying, combining, and expanding uncertainty components: Theory and examples</strong></h5><h5><strong>9:45 Precision uncertainty: Theory and examples</strong></h5><h5><strong>10:30 </strong>Coffee break</h5><h5><strong>10:50 Trueness-related uncertainty: Theory and examples</strong></h5><h5><strong>12:00 Additional questions and discussion</strong></h5><h5><strong>12:30 </strong>Lunch</h5><h5><strong>13:30 Application example 1</strong></h5><h5><strong>15:30 </strong>Coffee break</h5><h5><strong>15:50 Application example 2</strong></h5><h5><strong>17:00 Additional questions and discussion</strong></h5><h5><strong>17:30 Closing</strong></h5><h3><strong>Venue</strong></h3><p>The series of Eurachem events will be held in:</p><ul><li>Meliã Lisboa Aeroporto ****</li><li>Rua C,2 1749-125 Lisboa, Portugal&nbsp;</li></ul>

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Eurachem is a European network promoting international traceability of chemical measurements and good analytical practice. It provides expert guidance, supports method validation, uncertainty evaluation, proficiency testing, and facilitates discussion on technical and policy issues in analytical quality.

Eurachem/CITAC Workshop on Quality in Analytical Measurements 2026

VaMPIS - Validation of Measurement Procedures that Include Sampling

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