Laboratory internal performance data

Examples for the estimation of laboratory internal performance data ENV-ISO 13530 (ISO/TR, 2003) can be applied to ascertain the laboratory internal values for precision, trueness and LOD aceording to the EU directive 98/83/EC. The examples in Table 1.4 m give an indication for the internal actions to be applied by the laboratory. 

The large body of radiochemical data available from the low yield land-surface event Small Boy has been re-examined for internal consistency by a variety of methods. It was possible to show that certain portions of the data are not sufficiently reliable to be useful for establishing the fractionation behavior of fission-product radionuclides in the nuclear debris. Certain other parts of the data are shown to need adjustment for calibration differences which existed between the four laboratories which performed the analyses. Despite the shortcomings of the data, it was possible to establish that the relationships which existed among the fractionating radionuclides were qualitatively similar to those previously observed for other events. Other features of the data appear to be unique to Small Boy. 

Performances of dryers with simple flow patterns can be described with the aid of laboratory drying rate data. In other cases, theoretical principles and correlations of rate data are of value largely for appraisal of the effects of changes in some operating conditions when a basic operation is known. The essential required information is the residence time in the particular kind of dryer under consideration. Along with application of possible available rules for vessel proportions and internals to assure adequate contacting of solids and air, heat and material balances then complete a process design of a dryer. 

It is common practice to employ outside laboratories to perform testing for safety and efficacy measures in clinical trials. Along with the results, these laboratories will also provide the units and normal ranges for the tests performed. Since the laboratories are typically utilized by many patients in a study or even across studies, it is practical for the units and ranges to be received and entered once in the system and then linked internally to the patient data to which they apply. This principle of centrally storing values that can be shared across the system is also desirable for maintaining the conversion factors used in deriving lab results into standardized units. 

Available analytical performance data for fecal fat measurements in the UK also indicate that the test should now be consigned to history. Eighty-two per cent of laboratories use no internal quality control and EQA is impractical. When the titration step was assessed in an EQA exercise, between-laboratory coefficients of variation for three samples ranged from 31% to 42%. Infrared spectroscopy offers the possibility of improved within- and between-laboratory precision for fecal fat measurements, but does not address the problems of dietary input and sample collection, and is unlilcely to be available to most laboratories. 

Precision within a laboratory can be tightly controlled by the operation of internal quality control schemes. This can be achieved by undertaking replicated analysis of samples and/or possibly by analysing replicate samples. The analysis of certified reference materials offers a means whereby bias can be estimated. Another means of estimating a laboratory s performance is via participation in inter-laboratory proficiency-testing schemes. Originally, external quality control or inter-laboratory proficiency-testing schemes had been made available to assist laboratories to identify those areas where remedial action was considered necessary, in order to improve the quality of data... 

After completion of the validation experiments, a comprehensive report should be written. The format of the report may be dictated by internal policies of the laboratory however, such reports should summarize the assay performance data and deviations from the method SOP or validation plan and any other relevant information related to the conditions under which the assay can be used without infringing the acceptance criteria. 

The use of Equation (22) is very general, but it is also possible, with accurate measurements and data treatment, to perform the quantitative phase analysis in semi-crystalline materials without using any internal standard. This procedure is possible only if the chemical compositions of all the phases, including the amorphous one, are known. If the composition of the amorphous phase is unknown, the quantitative analysis without using any internal standard can still be used provided that the chemical composition of the whole sample is available [51]. This approach, until now, has been developed only for the XRD with Bragg-Brentano geometry that is one of the most diffused techniques in powder diffraction laboratories. 

In order to extrapolate laboratory animal results to humans, an interspecies dose conversion must be performed. Animals such as rodents have different physical dimensions, rates of intake (ingestion or inhalation), and lifespans from humans, and therefore are expected to respond differently to a specified dose level of any chemical. Estimation of equivalent human doses is usually performed by scaling laboratory doses according to observable species differences. Unfortunately, detailed quantitative data on the comparative pharmacokinetics of animals and humans are nonexistent, so that scaling methods remain approximate. In carcinogenic risk extrapolation, it is commonly assumed that the rate of response for mammals is proportional to internal surface area... 

The Directive contains these other requirements concerning toxicity information and test data (1) Notifications must include descriptions of the studies conducted and methods used (Article 6(1), and Annex VII, Introductory Statements) (2) The tests must be performed according to the methods specified in Annex V (Article 3(1)), and must be "recognized and recommended by the competent international bodies where such recommendations exist" (Annex VII, Introductory Statements) (3) The persons who carry out the tests must comply with the principles of current good laboratory practice (Annex VII, Introductory Statements) and (4) The notifications must include the composition of samples used in testing, and the name of the persons responsible for carrying out the studies (Annex VII, Introductory Statements). 

The ability to provide accurate and reliable data is central to the role of analytical chemists, not only in areas like the development and manufacture of drugs, food control or drinking water analysis, but also in the field of environmental chemistry, where there is an increasing need for certified laboratories (ISO 9000 standards). The quality of analytical data is a key factor in successfully identifying and monitoring contamination of environmental compartments. In this context, a large collection of methods applied to the routine analysis of prime environmental pollutants has been developed and validated, and adapted in nationally or internationally harmonised protocols (DIN, EPA). Information on method performance generally provides data on specificity, accuracy, precision (repeatability and reproducibility), limit of detection, sensitivity, applicability and practicability, as appropriate. 

By using the combination of specific method accreditation and generic accreditation it will be possible for laboratories to be accredited for all the analyses of which they are capable and competent to undertake. Method performance validation data demonstrating that the method was fit-for-purpose shall be demonstrated before the test result is released and method performance shall be monitored by on-going quality-control techniques where applicable. It will be necessary for laboratories to be able to demonstrate quality-control procedures to ensure compliance with the EN 45001 Standard,3 an example of which would be compliance with the ISO/AOAC/IUPAC Guidelines on Internal Quality Control in Analytical Chemistry Laboratories.12... 

Together with the fast development of analytical methodologies, great importance is nowadays attached to the quality of the measurement data. Besides the necessary reporting of any result with its MU and traceability of the results to stated standards or references (Section 8.2.2), a third crucial aspect of analytical methods of whichever type is their status of validation. It is internationally recognized that validation is necessary in analytical laboratories. However, less is known about what is validation and what should be validated, why validation is important, when and by whom validation is performed, and finally, how it is carried out practically. This Chapter has tried to answer these questions. 

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