Metrological aspects of devising methods for measuring the compositions of substances and materials

Abstract

Complete intbrmation on the compositions of substances and materials is a major condition for quality assurance in food products and consumer goods, as well as in handling ecological problems and improving the performance in any process or improving health care. As a rule, such data can be obtained by means of the latest analytical methods, which have developed vigorously in recent years.However, the use of the latest means of measurement is not necessarily decisive in obtaining reliable information about compositions. There may be losses while the sample is being prepared, incomplete allowance for the interactions between components, and unsuitability of specimens used to calibrate the instruments, together with other problems, which means that one needs to draw up sets of operations and rules to support obtaining results with a given error, i.e., one needs to draw up methods for making measurements MMM. Figure 1 shows the main stages in developing an MMM.In the technical specification lbr drawing up or revising the MMM, the following should be reflected: the basis tbr drafting or revising the MMM; brief characteristics of ttie object; possible measurement range for the relative parameter and possible ranges in the factors that influence the result (if any): accuracy specifications; the basis for choosing the measurement method, means of measurement, standard specimens, and so on: and deadlines for drafting or revising the MMM:The recipe tbr the MMM is drafted in accordance with Appendix C in standard [1].The MMM recipe should contain the following: introduction with description of the purpose of the MMM and statement of the measurement range tbr the relevant paranleter and the ranges for the factors that influence the result (if any); accuracy specifications and/or values for the error characteristics; brief description of the measurement method; list of means of measurement used, standard specimens, reagents, materials, and so on; measurement conditions; preparation procedures; operation sequence in the measurements; calculations on the result: values of standards used in checking the accuracy and a description 806