Reference material selection

Tab. 4.7 IAEA radioisotope reference materials selected for upgrade (Fajgelj et al. 1999) Code Matrix Measurands Interest ...

In principle, the reference materials selected for the SFR from the corrosion point of view seem to be appropriate. However, advanced reactor design targets, e.g., the 60-year operational lifetime and the higher fuel bum-up to be reached using unexplored materials for the fuel cladding, raises some questions on the appropriate qualification status of the materials. To address these issues, on one hand experimental programs... 

Sing (see Ref. 207 and earlier papers) developed a modification of the de Boer r-plot idea. The latter rests on the observation of a characteristic isotherm (Section XVII-9), that is, on the conclusion that the adsorption isotherm is independent of the adsorbent in the multilayer region. Sing recognized that there were differences for different adsorbents, and used an appropriate standard isotherm for each system, the standard isotherm being for a nonporous adsorbent of composition similar to that of the porous one being studied. He then defined a quantity = n/nx)s where nx is the amount adsorbed by the nonporous reference material at the selected P/P. The values are used to correct pore radii for multilayer adsorption in much the same manner as with de Boer. Lecloux and Pirard [208] have discussed further the use of standard isotherms. 

National Institute of Standards and Technology (NIST). The NIST is the source of many of the standards used in chemical and physical analyses in the United States and throughout the world. The standards prepared and distributed by the NIST are used to caUbrate measurement systems and to provide a central basis for uniformity and accuracy of measurement. At present, over 1200 Standard Reference Materials (SRMs) are available and are described by the NIST (15). Included are many steels, nonferrous alloys, high purity metals, primary standards for use in volumetric analysis, microchemical standards, clinical laboratory standards, biological material certified for trace elements, environmental standards, trace element standards, ion-activity standards (for pH and ion-selective electrodes), freezing and melting point standards, colorimetry standards, optical standards, radioactivity standards, particle-size standards, and density standards. Certificates are issued with the standard reference materials showing values for the parameters that have been determined. 

Conditions of microwave sampling were selected using soil reference materials P-1, SP-1, SP-3, PKP, PDPV (Russia). 

Figure 27.1 summarises the methodology for designing a component which must carry load. At the start there are two parallel streams materials selection and component design. A tentative material is chosen and data for it are assembled from data sheets like the ones given in this book or from data books (referred to at the end of this chapter). At the same time, a tentative component design is drawn up, able to fill the function (which must be carefully defined at the start) and an approximate stress analysis is carried out to assess the stresses, moments, and stress concentrations to which it will be subjected. 

This book is designed as a handy desk reference covering fundamental engineering principles of project planning schemes and layout, corrosion principles and materials properties of engineering importance. It is intended as a general source of typical materials property data, useful for first pass materials selection in process design problems. 

Detailed designs for fume control systems and selection [Pg.1268]

If all of the material is not to be removed as overhead vapors from the still, leave a percentage of a particular compound in the bottoms, then select the particular compound as the reference material b for a determinations. 

ASM engineered materials reference book , 2nd edition, Michael L. Bauc-cio., ASM International (1994) ISBN 0871705028 (www. asm-intl.org). Compact compilation of numeric data for metals, polymers, ceramics and composites. This is an excellent reference for persons involved in nonmetallic materials selection, design, and manufacturing. Sections include ... 

This Chapter reviews some selected historical examples of the development, production and use of reference materials (RMs), from the past century up to the present. It is, of necessity, a rather short and incomplete review describing international efforts in this area. From the references given at the end of this Chapter and at the end of Chapter 3, the reader may investigate further into the past. 

The history of reference materials is closely linked with the development of analytical chemistry. In the 19th Century all chemicals were, in comparison with those of today, of poor purity. Thus, for volumetric analysis suitable purified materials as primary standards had to be specified. One of the first examples was the recommendation of As(III) oxide by Gay-Lussac (1824) for this purpose. Somewhat later, Sorensen (1887) proposed criteria for the selection of primary chemical standards. These were further elaborated by Wagner (1903) at the turn of the last century. It is worthwhile mentioning that their criteria were quite similar to those used today. 

Selection of method appropriate for homogeneity and stability testing Design of the characterization of the reference material Sampling... 

There are also RMs which are prepared for a specific application and are used for validation of relevant methods. Cobbaert et al. (1999) made use of Ion Selective Electrode (ISE)-protein-based materials when evaluating a procedure which used an electrode with an enzyme-linked biosensor to determine glucose and lactate in blood. Chance et al. (1999) are involved with the diagnosis of inherited disorders in newborn children and they prepared a series of reference materials consisting of blood spotted onto filter paper and dried, from which amino-acids can be eluted and... 

Traceability, however, is such an important concept that it will undoubtedly also be applied in future to radioisotopic reference materials. The IAEA is giving high priority to such work in its own reference material program. Table 4.7 provides details of some existing materials which have been selected for upgrade. 

Quality assurance of radiopharmaceutical preparation and use is obviously a very important topic because of its direct impact on patient diagnosis, treatment and health (see, e.g. Abreu 1996). Reference materials play only a small - but nevertheless important -role in this process, mainly in the area of calibration of radioactivity-measuring instruments. The materials of interest are all pure chemical containing calibrated activities of selected radionuclides used commonly in nuclear medicine (e.g. Co, Ga, I,... 

Ihnat M (1992) Selection and preparation of relevant reference materials for agricultural purposes. In Rossbach M, Schladot JD, Ostapczuk P, eds. Specimen Banking — Environmental Monitoring and Modem Analytical Approaches, pp 57-73. Springer, Berlin. 

Johnson AM, Sampson EJ, Blirup-Jensen S, Svendsen PJ 1996) Recommendations for the selection and use of protocols for assignment of values to reference materials. Europ J Clin Chem Clin Biochem 34 279-285. 

Simply producing reference materials is not enough they have to be used properly. Chapter 7 reviewed the proper use of RMs, but unless RMs and CRMs can be easily obtained and moved from one country to another without delays, duty or unnecessary controls, their use will be inhibited. Likewise, information about the materials that are available, their use, and their application should be freely available if analysts are to make informed decisions about the selection and use of a RM or CRM. It has already been made clear in previous Chapters that the correct choice of reference material for a particular application requires not only information about the RM, which is relatively easily available, but also information about the uses and applications of the reference material. Unfortunately, neither the availability of information about the reference materials and their uses nor their free movement across national borders are at all satisfactory. 

The revised database holds over 23 000 analyte values for 660 measurands and 1670 reference materials produced by 56 different producers, from 22 countries. The database is restricted to natural matrix materials (i.e. made from naturally occurring materials, excluding calibration standards manufactured from pure chemicals). Information has been extracted from the relevant certificates of analysis, information sheets, and other reports provided by the reference material producers. As a general rule, the authors have only included in the compilation reference materials for which a certificate of analysis or similar documentation is on file. Information included in the survey is on values for measurands determined in reference materials, producers, suppliers, the cost of the materials, the unit size supplied, and the recommended minimum weight of material for analysis, if available. The new searchable database has been designed to help analysts to select reference materials for quality assurance purposes that match as closely as possible, with respect to matrix type and concentrations of the measurands of interest and their samples to be analyzed see Table 8.3. 

Tab. 9.1 Selected driving forces that affect extent of reference material usage (arranged by pairs, in order of increasing external forces)...

If we consider only a few of the general requirements for the ideal polymer/additive analysis techniques (e.g. no matrix interferences, quantitative), then it is obvious that the choice is much restricted. Elements of the ideal method might include LD and MS, with reference to CRMs. Laser desorption and REMPI-MS are moving closest to direct selective sampling tandem mass spectrometry is supreme in identification. Direct-probe MS may yield accurate masses and concentrations of the components contained in the polymeric material. Selective sample preparation, efficient separation, selective detection, mass spectrometry and chemometric deconvolution techniques are complementary rather than competitive techniques. For elemental analysis, LA-ICP-ToFMS scores high. 

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