In-house method validation

LGC, In-House Method Validation. A Guide for Chemical Laboratories, ISBN 0-94892-618-X, LGC, Teddington, UK, 2003. 

There is concern in the food analytical community that although methods should ideally be validated by a collaborative trial, this is not always feasible for economic or practical reasons. As a result, IUPAC guidelines are being developed for in-house method validation to give information to analysts on the acceptable procedure in this area. These guidelines should be finalised by the end of 2001. 

Codex (2002) Codex committee on methods of analysis and sampling. In-house method validation (document CX/MAS 01/9). See also Codex committee on methods of analysis and sampling. Consideration of IUPAC guidelines for the in-house (single laboratory) validation of methods of analysis (document CX/MAS 02/10). 

King, B. In-house method validation A guide for chemical laboratories. LGC. 

For a laboratory performing an in-house method validation study, it is recommended that 10 test portions be analyzed at each concentration over the range of validation. 

Two types of method validation can be distinguished. Full method validation, of interest to the general scientific community, is carried out through an interlaboratory method performance study. Where a method becomes more routinely used it is reasonable to expect that the method should be fully validated. Internal method validation (single-laboratory method validation) is a scientific and technical alternative. It consists of validation steps carried out within one laboratory, for instance, to validate a new method that has been developed in-house or to verify that a method adopted from some other source is applied sufficiently well. A single-laboratory validation cannot assess between-laboratory variation and will provide an optimistic assessment of interlaboratory variability (cfr. Chp. 6.2.3 and 6.2.4). In-house method validation is described in the lUPAC, AOAC International, and ISO guidance [65,66]. There are several types of internal laboratory validation ... 

The degree of validation of the methods may be quite different. What validation means is that the method has been subject to a study which shows that, as applied in the user s laboratory, it provides results which are fit for their intended purpose. The method satisfies some pre-defined criteria. When standard or internationally agreed methods are being developed, the validation of the method is more complicated and time-consuming than that of methods developed in-house. Such validation involves a collaborative study using analysts working in a number of laboratories. This has already been mentioned in Chapter 1 and the organization of collaborative studies is discussed in Chapter 7. However, this more elaborate procedure does not necessarily mean that the method is more reliable than in-house methods. 

In-house methods are fully documented, appropriately validated and authorized for use. 

This chapter has two aims to demonstrate the necessity of using properly validated and verified methods and to explain what constitutes a validated method, and to provide an introduction to method validation for in-house methods. There is an abundance of published material that defines, describes, and generally assists with method validation, some of which is... 

ISO/IEC 17025 (ISO/IEC 2005, section 5.4) states that method validation is confirmation by examination and provision of objective evidence that the particular requirements for a specified intended use are fulfilled, and it stipulates protocols for validating in-house methods. Proper documentation is proof of validity. It is unlikely that many interested parties were present during the experiments and subsequent data analysis that demonstrated validity. Therefore, in many ways method validation is only as good as its documentation, which describes the method, the parameters investigated during the method validation study, the results of the study, and the... 

Internal code Samples Test field (Products or materials or type of activity tested) Measured principle Type of tests (Range of measurement, properties measured) Description Accredited Test method (method, from to standard, validated in-house method)... 

There are, however, few reports which deal with all parts of the development process. In Nordtest technical report 403, Observing validation, uncertainty determination and traceability in developing Nordtest test methods [5], the issues mentioned above are analysed and suggestions of how to handle them are made. The analysis is not only limited to Nordtest methods but is generally valid for all types of test methods, e.g. in-house methods developed at one laboratory or international standards used world-wide. 

In the TLC analysis of dry extracts prepared from medicinal plants, the sample preparation is performed in a different way from that prescribed in the monographs for the drugs in the pharmacopoeias. Also, there is no binder in the recommended solvent system, and in these cases a validation of the new in-house method is certainly necessary. 

Notwithstanding whether the method is an in-house method that has been provided/developed, a national method, or indeed an international method, validation of the method should be undertaken in the laboratory where the method is to be used. This is to ensure that the laboratory can demonstrate its capability in carrying out the method. Ideally, all national and international methods should have been inter-laboratory performance tested to establish their full capability or performance characteristics. These methods should be clearly and unambiguously written and the procedures strictly adhered to when performance testing is undertaken. However, in reality, this may not be the case for either situation. 

Is this always hue Whilst everyone is using the same standardised method, one will never know. Also there should not be continual discussions on the best in-house method. We have to realise that there will always be a soil for which a well validated method will fail. Is this a real problem ... 

Methods validation would be critically reviewed for completeness, accuracy and reliability. If an alternative to a compendial method is used, this in-house method must be compared to the compendial method to demonstrate it is equivalent or superior to the official procedure. Appropriate pharmacopoeial guidelines for methods validation should be followed. 

Many standard analytical methods have been published as papers in analytical journals and other scientific Uterature, and in textbook form. Collections by trades associations representing, for example, the cosmetics, food, iron and steel, pharmaceutical, polymer plastics and paint, and water industries are available. Standards organizations and statutory authorities, instrument manufacturers applications notes, the Royal Society of Chemistry and the US Environmental Protection Agency are also valuable sources of standard methods. Often, laboratories will develop their own in-house methods or adapt existing ones for specific purposes. Method development forms a significant part of the work of most analytical laboratories, and method validation and periodic revalidation is a necessity. 

Even if most examples and procedures presented apply to in-house validation, the procedure does not distinguish between validations conducted in a single laboratory and those carried out within inter-laboratory method performance studies. A preference for inter-laboratory studies can be concluded from the statement that laboratories should always give priority to methods which have been tested in method performance studies. Within the procedure a profound overview of different categories of analytical methods according to the available documentation and previous external validation is given. For example, if a method is externally validated in a method performance study, it should be tested for trueness and precision only. On the other hand, a full validation is recommended for those methods which are published in the scientific literature without complete presentation of essential performance characteristics (Table 9). 

Numerous radon and radon decay measurements in houses are now being made by a large number of private and governmental organizations. In order to assure valid and consistent measurements, it is important that proven methods be used following standardized procedures. To address this need, EPA issued "Interim Indoor Radon and Radon Decay Product Measurement Protocols" and established a Radon/Radon Progeny Measurement Proficiency program. 

Has the method been validated through any In-House Protocol ... 

F. Calbiani, M. Careri, L. Elviri, A. Mangia, L. Pistara and I. Zagnoni, Development and in-house validation of a liquid chromatography-electrospray-tandem mass spectrometry method for the simultaneous determination of Sudan I, Sudan II, Sudan II and Sudan IV in hot chili products. J. ChromatogrA, 1043 (2004) 123-130. 

Microbial recovery studies of membrane filtration method challenged with less than 100 CPU of each organism listed in USP-25, EP-2002 and in-house microbial isolates. Two lots of (Product Name) (Batch Numbers) have been validated in triplicate for each organism. Validation mimicked the test proper in every detail, such as in the volumes of media used, quantities and dilutions of product and diluents. 

Extent of Validation Depends on Type of Method On the one hand, the extent of validation and the choice of performance parameters to be evaluated depend on the status and experience of the analytical method. On the other hand, the validation plan is determined by the analytical requirement(s) as defined on the basis of customer needs or as laid down in regulations. When the method has been fully validated according to an international protocol [63,68] before, the laboratory does not need to conduct extensive in-house validation studies. It must only verify that it can achieve the same performance characteristics as outlined in the collaborative study. As a minimum, precision, bias, linearity, and ruggedness studies should be undertaken. Similar limited vahdation is required in cases where it concerns a fully validated method which is apphed to a new matrix, a well-established but noncol-laboratively studied method, and a scientifically pubhshed method with characteristics given. More profound validation is needed for methods pubhshed as such in the literature, without any characteristic given, and for methods developed in-house [84]. 

Use of Validated Methods In-Home Versus Interlaboratory Validation Wherever possible or practically achievable, a laboratory should use methods which have been fully validated through a collaborative trial, also called interlaboratory study or method performance study. Validation in collaborative studies is required for any new analytical method before it can be published as a standard method (see below). However, single-laboratory validation is a valuable source of data usable to demonstrate the fitness for purpose of an analytical method. In-house validation is of particular interest in cases where it is inconvenient or impossible for a laboratory to enter into or to organize itself a collaborative study [4,5]. 

On the one hand, even if an in-house vahdated method shows good performance and reliable accuracy, such a method cannot be adopted as a standard method. In-house validated methods need to be compared between at least eight laboratories in a collaborative trial. On the other hand, a collaborative study should not be conducted with an unoptimized method [58]. Interlaboratory studies are restricted to precision and trueness while other important performance characteristics such as specificity and LOD are not addressed [105]. For these reasons, single-laboratory validation and interlaboratory validation studies do not exclude each other but must be seen as two necessary and complementary stages in a process, presented in Figure... 

The second part of the scope refers to the kind of method used and makes clear that whether the method is an internationally recognized standard or simply and in-house procedure, it falls within the scope of ISO/IEC 17025. In specifying exactly what a laboratory is accredited for, the accreditation body must be careful to correctly detail the methods. So if sulfur is analyzed by ASTM D5453, the laboratory must have demonstrated its capability to follow the method as laid specified in the American Society for Testing and Materials standard, or any changes made by the laboratory must be documented and validated. 

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