Some recent developments in reference methodology within the United Kingdom

 The UK Valid Analytical Measurement Programme has pump-primed developments in chemical metrology, through a major project on reference methodology and reference materials. This paper provides an overview of developments during 1994–1997 and covers work on primary methods for trace inorganic and trace organic analysis, including the use of isotope dilution mass spectrometry; studies of sample pre-treatment, including digestion, extraction, and separation aimed at improving this weak link in the traceability chain; prioritisation, production and marketing of both pure substance and matrix reference materials; and international collaboration concerned with interlaboratory comparisons and the development of concepts, terminology and systems to underpin the international chemical measurement system. References are given to a number of papers covering specific parts of the programme. Received: 5 August 1998 · Accepted: 12 September 1998