Quality assessment measures

Fig. 1.3, The quality spiral described in Fig. 1,1 and its implementation depend on the tools available in the laboratory. These tools concern laboratory structure, personnel, management, external and internal quality assessment measures. The proper use of the available tools will lead to the development of the quality objectives (adapted from ref [10]).

With a prescriptive approach to quality assessment, duplicate samples, blanks, standards, and spike recoveries are measured following a specific protocol. The result for each analysis is then compared with a single predetermined limit. If this limit is exceeded, an appropriate corrective action is taken. Prescriptive approaches to quality assurance are common for programs and laboratories subject to federal regulation. For example, the Food and Drug Administration (FDA) specifies quality assurance practices that must be followed by laboratories analyzing products regulated by the FDA. 

In a performance-based approach to quality assurance, a laboratory is free to use its experience to determine the best way to gather and monitor quality assessment data. The quality assessment methods remain the same (duplicate samples, blanks, standards, and spike recoveries) since they provide the necessary information about precision and bias. What the laboratory can control, however, is the frequency with which quality assessment samples are analyzed, and the conditions indicating when an analytical system is no longer in a state of statistical control. Furthermore, a performance-based approach to quality assessment allows a laboratory to determine if an analytical system is in danger of drifting out of statistical control. Corrective measures are then taken before further problems develop. 

The program quality assurance plan may need periodic or emergency revisions Ongoing review of the data should reveal whether any deficiencies are due to Inadequate performance of vendors or to defects In the quality assurance plan Defects In the plan could result from Inadequate quality assessment techniques If measured levels of contaminants were significantly different from anticipated levels, for example ... 

ISO Guide 33 (1998) deals with other uses of RMs. It elaborates on various uses of RMs, excluding calibration, which is the subject of ISO Guide 32. In most cases, RMs are used as a quality control measure, i.e. to assess the performance of a measurement method. Most matrix RMs are produced with this purpose in mind. Other purposes of RMs are the maintenance of conventional scales, such as the octane number and the pH scale. ISO Guide 33 provides guidance on the proper use of RMs, and therefore it is together with ISO Guide 32 the most important document for users of CRMs. 

Measurements of individual laboratory performance provides for comparisons between laboratories. It then follows to ask why some laboratories report data that are more accurate and precise than do their peers, and a well designed external quality assessment scheme allows investigation of some of the important factors (see below). A comparison of performance between individual laboratories also helps to stimulate those who are not so successful to improve (or abandon the assay) and those who do well to continue with their expertise. Finally, changes of performance may be monitored as a consequence of some new factor, e.g. purchase of a new piece of equipment, work carried out by a different analyst, change to the methodology etc. 

Quality, unlike beauty is not simply in the eye of the beholder. Quality may be assessed, measured and evaluated, to be expressed in terms such as good-poor, acceptable-unacceptable. Quality may also improve or deteriorate depending on the efforts, enthusiasm and expertise of the analysts and the environment in which the work is carried out. 

With respect to method application, once validation has been satisfactorily completed, there is little question that use of the analytical method in worker safety and re-entry studies falls under the full requirements of the GLP Standards. In addition, there should be an adequate level of quality control measurements taken in conjunction with the specimens so as to provide for a meaningful assessment of accuracy and precision, as well as verification of freedom from artifactual interferences. Along with these measurements there needs to be reasonably rigid data acceptance criteria in place (usually established during validation) which are consistently applied during the course of the specimen analytical phase of the study. 

Pork is the product of a very complex process. All the various characteristics of pork quality cannot be assessed directly in each carcass because these measurements and assessments would be too expensive. Therefore, previous scientific quality assessment of meat is primarily an indirect approach based on a few easily detectable quantitative traits and on the prescription of minimal standards in relation to the product in terms of size or composition and in relation to the production process. The prescriptions and the exclusion criteria vary between countries or between labelling programmes. The most encompassing prescriptions are enshrined in the EC regulation on organic livestock production (EEC No. 2092/91). Owing to this approach, extreme deviations in quality traits and deleterious effects are prevented. However, there is still space left within these framework conditions for huge variability in pork quality. 

Quality control describes the measures used to ensure the quality of individual results or a batch of results. The measures used will vary according to the particular application. It is a means of evaluating the current performance of the method being used and the general procedures used in the laboratory. There are two types of quality control, namely internal quality control and external quality assessment. These are covered in detail in Chapters 6 and 7, respectively. 

Besides the intake interview, which can help gather information, there are a number of assessment measures for determining the quality of an important interpersonal relationship. The questions on these measures generally ask about things like communication styles, satisfaction in the relationship, joint decision making, and in some cases, abusive behavior. Two of the most well-known measures are the Dyadic Adjustment Scale (Spanier, 1976) and the Marital Satisfaction Inventory (Snyder, 1979). Therapists and counselors also may choose to interview couples together (with the consent of client and partner), and some therapists may recommend couples therapy (see Chapter 5) as part of the overall approach to treatment if deemed appropriate to help the client. Relationship assessments can yield important information that may be useful when working with couples. 

Because of the status of the CAC described above, the work that it has carried out in the area of laboratory quality assurance must be carefully considered. One of the CAC Committees, the Codex Committee on Methods of Analysis and Sampling (CCMAS), has developed criteria for assessing the competence of testing laboratories involved in the official import and export control of foods. These were recommended by the Committee at its 21st Session in March 19979 and adopted by the Codex Alimentarius Commission at its 22nd Session in June 1997 10 they mirror the EU recommendations for laboratory quality standards and methods of analysis. The guidelines provide a framework for the implementation of quality assurance measures to ensure the competence of testing laboratories involved in the import and export control of foods. They are intended to assist countries in then-fair trade in foodstuffs and to protect consumers. 

It has now been established beyond any reasonable doubt that quality of a drug product cannot simply be ensured by inspection or analysis, but a control system has to be built into, from the very beginning of manufacture of a drug. Besides effective quality control measures exercised in every aspects of production including environment, screening of raw materials, process controls, intermediate shelf-life of finished products the most important aspect is to assess the bioavailability of the active principle. 

Heptachlor and heptachlor epoxide have been detected in several aquatic species. Heptachlor was measured in shrimp collected from the Calcasieu River/Lake Complex in Louisiana at concentrations ranging from 10 to 750 ppb (Murray and Beck 1990). A survey of organic compound concentrations in whole body tissues of the Asiatic clam Corbicula manilensis was conducted on the Apalachicola River in northwest Florida in 1979-1980 as part of the Apalachicola River Quality Assessment. Heptachlor epoxide was detected in the whole body tissue of the clam at concentrations ranging from <0.1 to 0.6 ppb, with a median concentration of 0.3 ppb (Elder and Mattraw 1984). 

Further on, the measure RMS distance that is to be optimized is a valuable point of information in itself. It is used, for example, to compare predictions with crystal structures and invaluable for clustering similar placements. However, caution must be taken to avoid problems with symmetry in the molecules. Again, the problem of correspondence must be treated carefuUy, since, for example, a rotation of 180° of a phenyl ring should not affect the result of such a quality assessment. 

Quality assurance embraces both QC and quality assessment. QC is defined as the mechanism or the practical activities undertaken to control errors, while quality assessment is the mechanism to verify that the system is operating within acceptable limits. Quality assessment and control measures are in place to ensure that the measurement process is stable and under control [2,8]. 

Some important assays commonly used in biochemical genetics laboratories do not provide quantitative data (e.g. MPS-EP, qualitative urinary organic acid analysis, AA-TLC). In addition, all successful investigations depend heavily upon selection of the correct analytes to measure and the appropriate interpretation of the quantitative or qualitative results in their clinical context. These challenges suggest a requirement for external quality assessment or proficiency testing schemes that can inform participants about their performance in these areas when compared with other centres. 

For quality assessment of an analytical process, a control chart could show the relative deviation of measured values of calibration check samples or quality control samples from their known values. Another control chart could display the precision of replicate analyses of unknowns or standards as a function of time. 

To identify comparable non-critical areas, N02 and PM levels and the trend of these pollutants were analysed in cities across the EU. Taking the criteria for non-critical areas into account, Berlin was selected as a comparable non-critical area.7 Other cities or areas which fit the criteria for non-critical areas either have a special emission structure (which eases abatement measures), or they are comparably small, or largely comparable to Berlin with respect to their dispersion conditions or modal split of traffic in several cases the available information about air quality assessment and management is not enough. Therefore, Berlin is the only non-critical area which is discussed here in detail. 

Colomes et al., 1994] Colomes, C., Lever, M., and Dehery, Y. F. (1994). A perceptual objective measurement POM system for the quality assessment of perceptual codecs. Contribution to the 96th AES Convention, Amsterdam, February 1994, Preprint 3801. 

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