CITAC (Coorperation on International Traceability in Analytical Chemistry)
Abstract
The article reviews the Eurachem Workshop on ‘Uncertainty from sampling and analysis for accredited laboratories’, that was held in conjunction with Eurolab-Germany and CITAC, at BAM in Berlin on November 19th-20th 2019. This two-day Workshop attracted over 140 participants from 27 counties, who made 30 presentation, both orally and as posters. One of its objectives was to launch the Second Edition of the Eurachem/CITAC Guide on Measurement Uncertainty arising from Sampling. The first day was therefore mainly focused on UfS and several of the new ideas in this area that have been incorporated into the revised Guide. For example, the Uncertainty Factor was explained as a better way to express measurement uncertainty (U) when the values are large (e.g. U > 20%), and when the frequency distribution of the uncertainty is shown to be log-normal, rather than the Gaussian that is usually assumed. Some examples where given where this asymmetry in the uncertainty was seen to arise from the sampling process, but other examples arose from purely analytical sources, such as the determination of genetically modified organisms (GMOs) in soya
