Analytical protocols internal

Internal quality control is undertaken by the inclusion of particular reference materials, called control materials , into the analytical sequence and by duplicate analysis. The control materials should, wherever possible, be representative of the test materials under consideration in respect of matrix composition, the state of physical preparation and the concentration range of the analyte. As the control materials are treated in exactly the same way as the test materials, they are regarded as surrogates that can be used to characterise the performance of the analytical system, both at a specific time and over longer intervals. Internal quality control is a final check of the correct execution of all of the procedures (including calibration) that are prescribed in the analytical protocol and all of the other quality assurance measures that underlie good analytical practice. IQC is therefore necessarily retrospective. It is also required to be as far as possible independent of the analytical protocol, especially the calibration, that it is designed to test. 

Currently, high-performance liquid chromatography (HPLC) methods have been widely used in the analysis of tocopherols and tocotrienols in food and nutrition areas. Each form of tocopherol and tocotrienol can be separated and quantified individually using HPLC with either a UV or fluorescence detector. The interferences are largely reduced after separation by HPLC. Therefore, the sensitivity and specificity of HPLC methods are much higher than those obtained with the colorimetric, polarimetric, and GC methods. Also, sample preparation in the HPLC methods is simpler and more efficiently duplicated than in the older methods. Many HPLC methods for the quantification of tocopherols and tocotrienols in various foods and biological samples have been reported. Method number 992.03 of the AOAC International Official Methods of Analysis provides an HPLC method to determine vitamin E in milk-based infant formula. It could probably be said that HPLC methods have become dominant in the analysis of tocopherols and tocotrienols. Therefore, the analytical protocols for tocopherols and tocotrienols in this unit are focused on HPLC methods. Normal and reversed-phase HPLC methods are discussed in the separation and quantification of tocopherols and tocotrienols (see Basic Protocol). Sample... 

CRMs allow the user to link his results with those of internationally recognised standards, i.e. they enable the user to verify his performance at any desired moment in terms of accuracy. CRMs can be pure substances or solutions to be used for calibration and/or identification, materials of a known matrix composition for the calibration of a certain type of comparative measuring instruments, matrix RMs representing as far as possible the matrix being analysed by the user (with a certified content), or methodologically defined RMs (certified following a very strict analytical protocol), e.g. a standard (Quevauviller et al., 1995a). 

ICP-MS-coupled techniques are expected to increase in popularity, possibly leading to the commercial availability of ready-to-use speciation systems. Among the several approaches so far developed for species identification and quantification with ICP-MS detection in foods, some led to the establishment of sufficiently practicable and reliable analytical protocols for selected analytes/matrices. In a few cases, therefore, there is already the potential for validating routine control methods and this should facilitate the laying-down of species-specific regulations in the international legislation on trace elements in food. 

The analytical protocols used to characterize hazardous wastes are primarily the EPA-approved methodologies found in their publication Test Methods for the Evaluation of Solid Waste, Physical/Chemical Methods, SW-846. Because these methodologies are a part of the waste analysis plan and the feed-stream analysis plan, they are required by the facility s RCRA permit. In the case of the feedstream analysis plan and the LDRs, adherence is required to meet specific regulatory requirements. Occasionally, DuPont will analyze streams for hazardous constituents or properties other than those required under the permit or regulations in order to address a specific issue (e.g., to determine if the stream can be recycled). Analyses like these should be considered not as an industrial best practice but only as an internal planning aid. 

An important aspect of trace analysis is that rigorous quality control must be included in analytical protocols if the results are to withstand international scrutiny. In cases of allegations of CW use, a chain of custody must be maintained and any positive analysis must be preceded by... 

This procedure ( ) has been used since 1982 by EPA for routine investigations. The analytical protocol requires complete extraction of the sample followed by liquid chromatographic cleanup and isomer-specific 2,3,7,8-TCDD analysis by high resolution gas chromatography/low resolution mass spectrometry. The extraction begins with ten grams of soil which is spiked with internal surrogate CI4-2378-... 

One consequence was that considerable human and financial resources were wasted and fundamental knowledge denied. An overall lack of agreement on analytical protocols and best practice also bedeviled attempts to build on data produced in different laboratories. This is not to overly criticize the activities conducted, rather it represented the barriers to effective international cooperation and funding available. 

In this section we provide some practical considerations to chemists not familiar with the use of immunoassays for food contaminants. We focus primarily on the use of 96-well microtiter ELISA. Regardless of the type of sample and analysis, good laboratory practices (GLPs) and international standards organization (ISO) standards, where they apply, need to be followed to ensure the quality of results and the minimization of variability. Like any other analytical protocol, the analysis of contaminants by immunoassay is a combination of three sequential steps sample collection and preparation, sample analysis, and data processing followed by the interpretation of results. 

Association of Official Analytical Chemists (1995) AOAC/ lUPAC revised protocol for the design, conduct and interpretation of method-performance studies. Journal of the Association of Official Analytical Chemistry International 78 143A-160A. 

The primary purposes for which reference materials are employed are encompassed within the laboratory Quality Assurance Procedures. Quality assurance comprises a number of management responsibilities which focus on how the laboratory is organized, how it deals with situations, how it interacts with users, together with analytical responsibilities re internal quality control and external quality assessment (Sargent 1995 Burnett 1996). Ideally each component follows a documented protocol and written records of all activities are maintained. 

Thompson M, Wood R (1993) International harmonized protocol for proficiency testing of (chemical) analytical laboratories. J of AOAC Intern 76 926-937. 

Method performance study All laboratories follow the same written protocol and use the same test method to measure a quantity (usually concentration of an analyte) in sets of identical test samples. The results are used to estimate the performance characteristics of the method, which are usually within-laboratory- and between-laboratory precision and - if relevant - additional parameters such as sensitivity, limit of detection, recovery, and internal quality control parameters (IUPAC Orange Book [1997, 2000]). 

IUPAC (1993) Analytical Chemistry Division, Commission on General Aspects of Analytical Chemistry The International Harmonized Protocol for the Proficience Testing of (Chemical) Analytical Laboratories. Pure Appl Chem 65 2123... 

ISO has two important functions in analytical chemistry. The first is to publish descriptions of accepted methods. These are effectively industry standard methods for particular protocols. The second is in laboratory accreditation. For a laboratory to be ISO accredited, compliance with international QA standards must be confirmed by an initial assessment and subsequently from repeated audits by an independent assessor. Since ISO has no legal or regulatory powers, the standards are voluntary. It is unlikely, however, that a forensic analysis which did not conform to an ISO standard would be upheld in court, for example. Most commercial laboratories need to be accredited to remain competitive and to deal with regulatory authorities. Most university labs are not accredited, mainly due to the time and costs involved, and also to the nonroutine nature of much university research. However, university accreditation may become a requirement in the near future, especially for publicly funded research in the UK. The details of laboratory accreditation are discussed by Christie et al. (1999) and Dobb (2004). 

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. 

ISO, IUPAC and AOAC INTERNATIONAL have co-operated to produce agreed protocols on the Design, Conduct and Interpretation of Collaborative Studies 14 and on the Proficiency Testing of [Chemical] Analytical Laboratories .11 The Working Group that produced these protocols has prepared a further protocol on the internal quality control of data produced in analytical laboratories. The document was finalised in 1994 and published in 1995 as the Harmonised Guidelines For Internal Quality Control In Analytical Chemistry Laboratories .12 The use of the procedures outlined in the Protocol should aid compliance with the accreditation requirements specified above. 

The protocol sets out guidelines for the implementation of internal quality control (IQC) in analytical laboratories. IQC is one of a number of concerted measures that analytical chemists can take to ensure that the data produced in the laboratory are fit for their intended purpose. In practice, fitness for purpose is determined by a comparison of the accuracy achieved in a laboratory at a given time with a required level of accuracy. Internal quality control therefore comprises the routine practical procedures that enable the analytical chemist to accept a result or group of results as fit-for-purpose, or... 

ISO/IUPAC/AOAC International Harmonised Protocol For Proficiency Testing of (Chemical) Analytical Laboratories... 

Consideration of the above requirements confirms that in future all methods must be fully validated if at all possible, i.e. have been subjected to a collaborative trial conforming to an internationally recognised protocol. In addition this, as described above, is now a legislative requirement in the food sector of the European Union. The concept of the valid analytical method in the food sector, and its requirements, is described below. 

Precision is defined as the closeness of agreement between independent test results obtained under prescribed conditions.19 In a standard method the precision characteristics are obtained from a properly organised collaborative trial, i.e. a trial conforming to the requirements of an International Standard (the AOAC/ISO/IUPAC Harmonised Protocol or the ISO 5725 Standard). Because of the importance of collaborative trials, and the resource that is now being devoted to the assessment of precision characteristics of analytical methods before their acceptance, they are described in detail below. 

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