Internal Quality Assurance and Control

Internal quality assurance and control procedures are designed to guarantee the reliability of the results generated by the laboratory QA and QC ensure that the reported results contain the appropriate accuracy and precision through stringent monitoring of the analytical process, documentation of procedures and method validation. 

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LYNN D. TORBECK is an International Consultant specializing in applied statistics and experimental design for pharmaceutical and biopharmaceutical development, quality assurance, and control validation, Torbeck Associates, Inc., Evanston, Illinois. Mr. Torbeck received the B.S. and M.S. degrees in Statistics, University of Tennessee, Knoxville, and formerly was Director of Validation World-Wide Quality Assurance, C. D. Searle (Pfizer), Skokie, Illinois. 

Before participating in interlaboratory studies the laboratory must have set-up all adequate internal quality assurance and quality control systems [7]. This also means that all basic investigations have been performed for possible mistakes, that these have been noticed and corrected. In other words the laboratory has validated the method to be applied. For a laboratory performance study, this also implies that in the laboratory the method is under statistical control for a given type of matrix, that this control is monitored and that results are evaluated. 

Khan, A. H, Azhar, S., Mahmood, A. (2008). Quality assurance and control in the construction of infrastructure services in developing countries — A case study of Pakistan. Proceedings of the first International Conference on Construction in Developing Countries (ICCIDC-I). 4—5 Aug 2008, Karachi, 109-120. 

Briefly, the quality management system is a combination of quality management, quality control and quality assurance. Quality assurance and quality control are components of the laboratory s quality management system. There is often confusion over the meaning of quality control and quality assurance and regrettably they are often used interchangeably. This is possibly because some quality control and quality assurance actions are interrelated. The definition of the terms can be found in the International Organization for Standardization (ISO) Standard, ISO 9000 2005 [2],... 

The previous chapters of this book have discussed the many activities which laboratories undertake to help ensure the quality of the analytical results that are produced. There are many aspects of quality assurance and quality control that analysts carry out on a day-to-day basis to help them produce reliable results. Control charts are used to monitor method performance and identify when problems have arisen, and Certified Reference Materials are used to evaluate any bias in the results produced. These activities are sometimes referred to as internal quality control (IQC). In addition to all of these activities, it is extremely useful for laboratories to obtain an independent check of their performance and to be able to compare their performance with that of other laboratories carrying out similar types of analyses. This is achieved by taking part in interlaboratory studies. There are two main types of interlaboratory studies, namely proficiency testing (PT) schemes and collaborative studies (also known as collaborative trials). 

Sampling is just the beginning of the analytical process. On the way from sampling to the test report a lot of different requirements for high quality measurements have to be considered. There are external quality assurance requirements on the quality management system (e.g. accreditation, certification, GLP), internal quality assurance tools (e.g. method validation, the use of certified reference material, control charts) and external quality assurance measures (e.g. interlaboratoiy tests). 

Maintaining the integrity of data is a primary goal of the quality assurance and quality control policies and procedures used by many companies, universities, and national and international agencies. 

Several recommendations arose from the interlaboratory smdy to minimize analytical challenges and to ensure data quality. As discussed above, it is recommended that mass labelled PFCs be employed as internal standards [93, 97]. It should be noted, however, that some electrospray ionization suppression may still occur if these internal standards are used at high concentrations [97]. Matrix effects can also be minimized by employing matrix-matched calibration standards in lieu of solvent-based calibration standards [97]. Unfortunately, matrix-matched standards can be impractical when an appropriate clean matrix cannot be found [94]. Other quality assurance and quality control measures, such as spike and recovery analyses of an analyte added to the sample matrix, repetitive analysis of samples to determine precision and comparison of internal standard quantitation to quantitation via standard additions, are also useful in determining data quality [94]. 

Kig, 1,2. Quality assurance and quality control are strongly inttueneed by internal structural and external regulatory parameters. When planning the work, the laboratory must take them into account (adapted from ref. [lOj). 

The sixth step in the design of an air monitoring survey is the development of a quality assurance and quality control plan. This plan should include specific sampling procedures, calibration procedures and frequency, sample custody, analytical procedures, data reduction, internal quality control checks, performance and system audits, completeness, and corrective action. 

Internal quality assurance is concerned with maintaining precision within a single laboratory, where the importance of keeping careful records, based on reference materials and using appropriate control charts is well established. External quality assurance involves reference materials obtained from an outside body, and is a method for testing the bias of laboratory results. In practice, internal quality assurance mainly has to do with laboratory precision, whereas external quality assurance mainly has to do with laboratory bias (ISO 5725,1986). 

In this section, discussion is limited to suppliers of reference materials which are available internationally, i.e. we are concerned here more with external quality assurance than with internal quality assurance. This is not intended to minimize the importance of reference materials for internal quality assurance indeed these are essential for monitoring the precision of the analytical methods and for establishing statistical control, e.g. using control charts. 

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