Metrology in chemistry

Metrology in Chemistry and Traceability of Analytical Measnrement Results... 

Metrology in Chemistry and Traeeability of Analytieal Measurement Results 209... 

Detailed information relating to metrology in chemistry and traceability can be obtained from these web-sites. The addresses include international and regional organizations as well as some national metrology institutes. 

Summarizing this chapter, you must remember that metrology in chemistry is still a young discipline thus there is still a lot to be learned, traceability is not an aim by itself, but it is the way to achieve reliable and comparable results. Traceability can only be claimed when the uncertainty statement includes all the uncertainty contributions from the references and the measurement process. 

May W (1999) NIST SRMs. What they are, what they are NOT and their impact on the U.S. economy, international trade and quality of life. CITAC 99 Japan Symposium on Practical Realization of Metrology in Chemistry for the 21th Century, Nov 9-11, Tsukuba, Japan... 

The Royal Australian Chemical Institute has supported metrology in chemistry through its Hitchhiker s Guide to Quality Assurance series of seminars and workshops. These have been excellently organized by Maree Stuart and John Eames and have been well attended by the analytical community. I particularly thank John Eames for allowing me to use his approach for quality control materials in chapter 4. 

Key words Traceability Interlaboratory comparisons Reproducibility Traceability chain Metrology in chemistry... 

Adviser on Metrology in Chemistry to the Director of the Institute for Reference Materials and Measurements, European Commission - JRC, 2440 Geel, Belgium... 

Key words Traceability chain Metrology in chemistry Reference material Amount standard Validation... 

International comparability and hence acceptance of chemical measurement results is the common central aim of all international initiatives and organizations in the field of metrology in chemistry such as the Consultative Committee for Amount of Substance (CCQM), the Co-operation on International Traceability in Analytical Chemistry (CITAC), EURACHEM, EUROM-ET and others. This is a consequence of the globalization of trade and economy and other human activities,... 

In the field of chemical measurements, part (1) is now underway in many countries. The basis for (2) has been laid for ah kinds of measurements by the General Conference of the Meter Convention and includes high-level interlaboratory comparisons (key comparisons) as an important element [2, 3], Metrology in chemistry is included in this comparison system through CCQM [4, 5], In the following these two parts are dealt with in more detail. 

Such an intermediate level of secondary laboratories is also required in the field of metrology in chemistry. It is not so important whether these act as calibration or, more generally, as reference laboratories. What is important is that they are firmly linked to the national references and have the competence to carry these refer-... 

Although in its infancy, metrology in chemistry is already accepted by a number of governments as the means of ensuring that measurements made in different laboratories are comparable and traceable to common standards [1], The ultimate aim is to develop a structured chemical measurement system which will lead to mutual recognition and trust in measurements made in laboratories all over the world. This in turn will facilitate international trade, wealth creation through innovation, and enforceable and trusted regulations. 

Enormous progress has been made in applying this concept to chemical measurement and there is a growing amount of published work and associated conferences [3-5], This includs work on concepts, terminology, and primary methods and has led to the new approach of metrology in chemistry , which is a synthesis based on input from physical measurement metrolog-ists and analytical chemists. 

King B (1999) Metrology. In Chemistry Current Activities and Future Requirements in Europe, Report EUR N1907 EN, 1999, European Commission, Brussels... 

Valcarcel M, et al (1998) Metrology in Chemistry and Biology a practical approach. EUR 18405 EN, European Commission, Brussels... 

To have a network of laboratories at the top of a trace-ability system for chemical measurements instead of just the national metrology institute seems to be a requirement typical of metrology in chemistry and is under consideration in many industrialized countries, because the competence for chemical analysis in most countries (except U.S.A.) largely lies outside the domain of the metrology institutes. Another example that underpins this view is the development of metrology in chemistry in Switzerland, where the Swiss Federal Office of Metrology and Accreditation (METAS) and the Swiss Federal Laboratories for Materials Testing and Research (EMPA) jointly provide the national references for chemical measurements [2]. 

A firm link must exist to the national institute, in metrology in chemistry to the national standards network, at the primary level via transfer standards (e.g. reference measurements and/or reference materials) or other means by which traceability to the national standards is ensured. 

Traceability structures for pH and electrolytic conductivity measurement have been built up in this field. The measurement of these quantities is of high relevance to metrology in chemistry and of great economic and scientific importance. This is demonstrated by the high and still growing demand for traceability of measurement results for these quantities to national measurement standards. Furthermore, a new series of European standards on these topics is in preparation within CEN/TC 332. While traceability of pH measurement has been established as one of the PTB s first actions in metrology in chemistry [5], the necessary building blocks for a trace-ability structure for electrolytic conductivity have been installed only recently [6],... 

A tested example of a practical traceability structure has been described which has already proved useful in several fields of chemical analysis. It makes use of a national calibration service as a successful and efficient dissemination mechanism. An essential part of the structure is a network of high-level chemistry institutes at the national standards level providing the end points of traceability and coordinated by the national metrology institute. The need for a network of competence seems to be typical for metrology in chemistry for which in most countries the resources are largely to be found outside of the national metrology institute. 

The hierarchical approach to the traceability of pH measurements and pH reference materials is consistent with the agreed approach to traceability for metrology in chemistry [23]. Uncertainties stated for the primary method and for all subsequent measurements permit the uncertainties for all steps to be linked to the primary reference material. 

In Mexico this task was initiated by CENAM in 1992. Particularly in the field of metrology in chemistry, the strategy has been developed in a parallel way to the work of the Consultative Committee for the Quantity of Matter (CCQM), by adopting the definitions of primary method of measurement and primary reference material given in the first CCQM meeting in 1995 [1], These definitions... 

White Paper (2000). Report of Governmental Transition, 1994 2000, Laboratories of Metrology in Chemistry Bildg. Q Establishment of traceability... 

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