The EUREKA E! 3106 UNCERTAINTY MANAGER project has developed a powerful and versatile software-based system and a supporting database to provide a fast, reliable and simple-to-use method of evaluating measurement consistency in analytical chemistry. As a result of this development, it is now possible to carry out uncertainty assessments in private as well as public laboratories automatically in minutes, guaranteeing worldwide comparability in chemical testing results. Such an approach plays an important role, from the routine quality control of goods for freer trade and the confirmation of the accuracy of doping tests on athletes, to making tougher environmental and waste control legislation possible.
Knowing the real value of measurements is crucial to open trade and application of effective legislation in many sectors. No measurement is perfect - variations can arise from random effects such as short term fluctuations in temperature, humidity or air pressure, from the performance of the people involved and from the practical limits of the test equipment itself. Repeat measurements vary because of such random effects. Other restrictions include the practical limits of correction for systematic effects, personal bias in reading scales or imprecision in reference standards.
However, the 25,000 accredited private and public control laboratories around the world must take the same approach to checking the values of routine tests in areas from testing and calibration to food, beverage and pharmaceutical quality, environmental waste control and sports medicine. The range of values that can reasonably be attributed to a measured quantity is known as uncertainty. Knowledge of the uncertainty provides a quantitative indication of the quality of a result. It shows how well the result represents the value being measured and enables comparison of results from different sources.
We believe UNCERTAINTY MANAGER offers an important contribution to the comparability of measurements worldwide. \div class="name">Dr Bruno Wampfler,
To meet the need for a coherent method of comparing measurements, the International Standards Organisation (ISO) launched its Guide to the expression of uncertainty in measurements (GUM) in 1995. This is applicable to all fields but addresses principally physical quantities. The European analytical chemistry association EURACHEM and the international Cooperation on International Traceability in Analytical Chemistry (CITAC) organisation produced a joint guide - Quantifying uncertainty in chemistry - that translates GUM for chemical analysis. The guide is important in areas such as manufacturing quality control, regulatory compliance, calibration of standards and equipment, and certification of reference materials, as well as research and development.
However, both these guides tend to be complicated, theoretical and time consuming. "We needed software to remove the barriers," explains Dr Bruno Wampfler of the Swiss federal materials science and technology research institute Empa, coordinator of UNCERTAINTY MANAGER.
This two-year EUREKA project brought together food and drug companies and involved project participants from Austria, Germany and Switzerland, measuring equipment suppliers, testing laboratories, information technology (IT) specialists, research centres and universities to speed up and automate uncertainty assessment.
There are some 20 software programmes currently available around the globe to help in determining measurement uncertainty but they are based mainly on time-consuming manual spreadsheet methods. The EUREKA project has developed a much easier to use and much faster approach to such determinations. The UNCERTAINTY MANAGER programme is designed to run on a standard personal computer (PC). Its unique benefits include fully automated evaluation of uncertainty effects, a large reference database and a powerful reporting tool.
EUREKA's bottom-up approach allows companies and co-operating partners to retain full control, deciding for themselves on the topics of their research as well as the money they want to invest.
Users input a sequence of information that consists of measurement equations, manufacturers and types of measurement tools, sample preparation conditions, types of calibration, environmental conditions including information on whether methods are standardised or not. A series of templates is provided to help guide users through these various steps. The software then makes a totally automatic evaluation of all the effects that are responsible for uncertainties. There is also a large database which allows the software to propose quantification of each step.
The output of the programme comes in the form of a detailed report - up to 120 pages long - of the overall uncertainty evaluation.
"Our software now allows evaluation of the measurement uncertainty of complex testing procedures in ten minutes," says Dr Wampfler. "We believe the UNCERTAINTY MANAGER system offers an important contribution to the comparability of measurements worldwide." The new tool meets the requirements of ISO 17025 on measurement uncertainty, is fully compliant with GUM, and follows the recommendations in the EURACHEM/CITAC guide to quantifying uncertainty in chemistry.
The direct benefits of the UNCERTAINTY MANAGER software system will be seen by companies involved in international trade as well as by individuals such as athletes involved in drug testing - uncertainty doubts will literally be removed from the test equation. Society will also benefit from the possibilities offered by more consistent testing in allowing the introduction of tougher environmental legislation based on more carefully defined limits and of more effective waste controls.
EUREKA played an important role in the establishment of the project. "The reputation of the EUREKA label enabled us to obtain industrial participation in this project and is helping us to gain valuable visibility for the results," adds Dr Wampfler. Following the end of the project, the software system is already being made available through project partner VWR International, with continuing technical support being provided by Empa.