Quality Assurance and Control

Clearly, the commercial or consultancy laboratory that tests sub-samples of a marketed product worth millions of pounds, or assesses the purity of pharmaceuticals, or analyses forensic samples, must have far higher levels of both accuracy and verifiability than student practical classes. There should, however, always be an effort to produce the most accurate and reliable results within the constraints of the laboratory facilities available, otherwise a lax attitude will produce work of doubtful interpretation that could mislead others, as well as giving little job satisfaction. Several books, which are more suited to the commercial sector, have been written on the quality of laboratory analysis, however some quality assurance practices could be beneficial in the smaller laboratory. A useful open-learning style book on basic concepts of quality in the analytical laboratory has been co-authored by staff at the Laboratory of the Government Chemist (Crosby et al., 1995).

The Laboratory of the Government Chemist (LGC) website is at:

http://www.lgc.co.uk Two important definitions are those of quality control and quality assurance. The former relates to operational techniques and activities, whereas the latter ensures that systematic actions are in place which enable confidence that the results meet the required level of quality, such as accuracy and precision. The concept of total quality control extends to areas such as management style and reduction of waste.

Quality control would include the following:

1. Analysis of replicates to determine precision;

© 2002 CAB International. Methods in Agricultural Chemical Analysis: a Practical

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2. Blank samples to detect impurities in the reagents or interferences;

3. Standard reference materials to check the accuracy of the method.

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