In this chapter the actual execution of the jobs for which the laboratory is intended, is dealt with. The most important part of this work is of course the analytical procedures meticulously performed according to the corresponding SOPs. Relevant aspects include calibration, use of blanks, performance characteristics of the procedure, and reporting of results. An aspect of utmost importance of quality management, the quality control by inspection of the results, is discussed separately in Chapter 8.
All activities associated with these aspects are aimed at one target: the production of reliable data with a minimum of errors. In addition, it must be ensured that reliable data are produced consistently. To achieve this an appropriate programme of quality control (QC) must be implemented. Quality control is the term used to describe the practical steps undertaken to ensure that errors in the analytical data are of a magnitude appropriate for the use to which the data will be put. This implies that the errors (which are unavoidably made) have to be quantified to enable a decision whether they are of an acceptable magnitude, and that unacceptable errors are discovered so that corrective action can be taken. Clearly, quality control must detect both random and systematic errors. The procedures for QC primarily monitor the accuracy of the work by checking the bias of data with the help of (certified) reference samples and control samples and the precision by means of replicate analyses of test samples as well as of reference and/or control samples. Calibration graphs
Construction and use
Error due to the regression line
Measuring a batch