Certification Philosophy of RM Producers

A review is presented here of certification approaches, followed by several of the major agencies and individual developers of RMs for chemical composition, addressing some of the many associated scientific aspects that significantly impinge on the conduct and outcome of the analytical characterization exercises. These include definition of analytical methods selection of analytical methodologies, analysts and laboratories in-house characterization and cooperative inter-laboratory characterization. 

The literature on RM certification indicates that there are two broad types of approaches for the characterization of RMs (i) statistical, and (2) measurement. The statistical approach relies on the in-depth application of statistical calculations to a body of analytical results obtained from diverse exercises, often widely scattered and discordant. The approach based on measurement emphasizes laboratory measurement aspects and deals more in detail with various diverse analytical measure- 

The key characteristic of a RM is that the properties of interest are measured and certified on the basis of accuracy. The means of attaining the true value are varied, and several different philosophies have been utilized in the quest for the best estimate of the true value. The goal of all approaches is arrival at the best possible estimate of the true value a reliable and unassailable numerical value of the concentration of the chemical constituent, under constraints of economics, state-of-the-art analytical technologies, availability of (new and old) methods, analyst competence, availability of analysts and RM end-use requirement. The basic requirement for producing reliable data is appropriate methodology, adequately calibrated and properly used. 

ISO 1985, 1996 Leaver and Bowman 1994a, 1994b, 19940 Marchandise 1985, 1987 Mavrodineanu 1977 McLaren et al. 1990 Morrison 1979 Quevauviller 1998  

Sim et al. 1987, 1988 Taylor 1993 Uriano and Gravatt 1977) a synopsis has appeared previously (Ihnat 1998). There are advantages and disadvantages to each certification approach. Usage is not necessarily clear-cut, and in many cases various combinations of these approaches have been used in certification. The most important consideration in any scheme is that systematic errors inherent in the methods 

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Certification Philosophy of RM Producers 59 Tab. 3.2 Assignment of certification approaches to various RM-developing organizations ... 

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