C. Grant – författare

The successful application of x-r~ diffraction techniques and x-r~ spectrometry depends in large measure on the availability of dependable standards and reference data. The preparation of such standards in the fields of metallurgy, geology, life sciences, and other disciplines is both costly and time consuming. As a result. the necessary standards for effective utilization of existing instrumentation are often not available. One of the purposes of the invited papers in this 22nd Annual Denver X-Ray Conference was tc review the status of programs to prepare such standards and reference data. Simultaneously, it seemed appropriate to examine the role of sampling both in terms of standards and samples to be analyzed. The first section of the invited papers focuses on the standards and reference data problems. In addition, many of the contributed papers offer information on this theme. The second topic in the invited papers consi­ ders the problem of sampling. If we recognize that analyses are conducted on samples which vary in size from several grams to a few micrograms or less, the magnitude of the random and systematic error components of sam­ pling on the quality of results should be obvious. Many of the contributed papers in such fields as air pollution and similar disciplines speak clear­ ly to the difficulty of obtaining "representative" samples. The papers contained in this volume and the many lively discussions such as the panel discussion at the close of the first session of papers should stimulate further attention to this vital topic.