Good measurement practices

Good measurement practices (GMPs) describe operations specific to a technique. In general, GMPs provide instructions for maintaining, calibrating, and using the equipment and instrumentation that form the basis for a specific technique. For example, a GMP for a titration describes how to calibrate a buret (if nec-... 

Quality control encompasses all activities used to bring a system into statistical control. The most important facet of quality control is written documentation, including statements of good laboratory practices, good measurement practices, standard operating procedures, and protocols for a specific purpose. 

Write directives outlining good measurement practices for (a) a buret, (b) a pH meter, and (c) a spectrophotometer. 

The individual scientist is the key to the production of quality data and must have technical competence and a dedication to quality work. Passive following of good laboratory practices and good measurement practices is not enough. Involvement in their development is required if the quality assurance program is to be credible. Standard operations procedures (SOPs) do not minimize the need for technical competence. Analysts exhibit varying degrees of proficiency when... 

The measurement - a quantified comparison by difference or ratio between two values of the same quantity -shall conform to well-accepted principles of the chemical profession and good measurement practice [12-... 

Many of the issues associated with traceability are well-established components of good measurement practice in chemical laboratories. However, some of the formalities are new and, until recently, the views of experts concerning the details of how to achieve the traceability of chemical measurements differed considerably. This has made it difficult to implement the traceability requirements of ISO/IEC 17025 in chemical testing laboratories. In recognition of this problem, CITAC and Eurachem have been working for over ten years to develop a widely agreed strategy... 

Whilst traceability is necessary to achieve comparability of measurement results, it is, of course, not the only requirement of good measurement practice and thus needs to be considered as just one part of the measurement process (2). 

To promote the dissemination and application of good measurement practice throughout Europe, particularly in the less favoured regions, for example, by the organization of training courses and by the establishment of networks. 

The interpretation of quality assurance is, according to ISO 9000, all those planned and systematic actions necessary to provide adequate confidence that the product or service will satisfy given requirements for quality . Basic elements of quality assurance are quality policy and activities of quality assurance programs, e.g., calibration, collaborative studies, good measurement practice (GMP), standard operating procedure (SOP), staff training, and instrument maintenance and inspection (audit). 

ETAAS electrothermal atomic absorption spectrometry GMP good measurement practice... 

Good measurement practices to mitigate artifacts, noise, and interference. 

Standard reference materials provide a necessary but insufficient means for achieving accuracy and measurement compatibiUty on a national or international scale. Good test methods, good laboratory practices, well-qualified personnel, and proper intralaboratory and intedaboratory quaUty assurance procedures ate equally important. A systems approach to measurement compatibiUty is ikustrated in Figure 2. The function of each level is to transfer accuracy to the level below and to help provide traceabiUty to the level above. Thus traversing the hierarchy from bottom to top increases accuracy at the expense of measurement efficiency. 

Calibration. Cahbration of lab instmments is important to the accuracy of test results. CaUbration, the use of an accepted standard to adjust an instmment or measurement standard so as to improve the accuracy of the instmment or measurement, is an essential requirement of both the U.S. Food and Dmg Administration (FDA) Good Manufacturing Practice (GMP) (24) and the ISO 9000 standards (25). 

When setting the goals of a measurement project, it has to be asked, What exactly has to be determined. What are the final quantities required and what is the inaccuracy that can be tolerated in these quantities Only when these factors are known can an analysis be made, where the quantities to be measured and the measurement accuracy of each quantity are defined. This analysis is based on the mea surement method selected, and on the computation of measurement uncertainties. Usually the analysis of measurement uncertainties is made after monitoring however, making it beforehand is part of good planning practice. This approach ensures that the correct information with the desired accuracy is achieved. 

In order to use any of the results obtained by objective methods as the basis for the acceptance or rejection of a product, there must be available reliable information as to the relationship between the values obtained and organoleptic quality in terms of consumer acceptance and utility. Where standards are based upon measurement of such labile constituents as ascorbic acid or sugar, a knowledge of the normal values for good commercial practice is necessary. Such values have not yet been adequately established. This should constitute a useful field for research of inestimable value to the industry. 

EURACHEM is a network of organizations in Europe, having the objective of establishing a system for the international traceability of chemical measurements and the promotion of good quality practices. It provides a forum for the discussion of common problems and for developing an informed and considered approach to both technical and policy issues. 

Analysts like to make chemical measurements to the highest quality they can, and this is possible with modem instrumentation and good analytical practice. Chemical parameters are generally measured more accurately and reproducibly than parameters measured in biological systems, and the results are more reliable than values calculated by software from structure alone (e.g., calculated log P, pKa). Of all the information available to medicinal chemists, measured chemical parameters are probably the most reliable. With these thoughts in mind, it makes sense not to... 

Member States shall take all measures necessary to ensure that the laboratories referred to in Article 7 of Directive 89/397/EEC1 comply with the general criteria for the operation of testing laboratories laid down in European standard EN 450013 supplemented by Standard Operating Procedures and the random audit of their compliance by quality assurance personnel, in accordance with the OECD principles Nos. 2 and 7 of good laboratory practice as set out in Section II of Annex 2 of the Decision of the Council of the OECD of 12 Mar 1981 concerning the mutual acceptance of data in the assessment of chemicals.4... 

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