Reference, analytical method laboratory

Analytical and Laboratory Operations. Sulfamic acid has been recommended as a reference standard in acidimetry (55). It can be purified by recrystaUization to give a stable product that is 99.95 wt % pure. The reaction with nitrite as used in the sulfamic acid analytical method has also been adapted for determination of nitrites with the acid as the reagent. This reaction is used commercially in other systems for removal of nitrous acid impurities, eg, in sulfuric and hydrochloric acid purification operations. 

The MDL and practical quantitation limit (PQL) should be appropriate for the objectives of the analysis. MDL refers to the minimum concentration of the compound of interest that can be measured and reported with a specified confidence (99% probability) that the concentration is above zero. The registrants must provide or develop an analytical method for water for the parent pesticide and its degradates that has an MDL of 0.01% of the label application rate (calculated as the average concentration in the top six inches of soil), or 0.05 pgL , whichever is lower. PQL refers to the lowest concentration at which the laboratory can confidently quantify the concentration of the compound of interest. The study authors must report all samples with concentrations above the MDL as detections, including those below the PQL in which the concentration cannot be quantified. In addition, the study authors must provide sample equations to demonstrate how the PQL was calculated. 

The availability of reference materials or standards will not solve all the analytical problems faced by the marine community. In addition to using reference materials, the use of agreed-on common collection and analytical methods can also improve the chemical data being collected by oceanographers. Standardization of these methods minimizes the variability that may result from differences in laboratory procedure. A major disadvantage of method standardization, however, is that it can discour-... 

Finally, one aspect that can pay a role in compositional studies is the sieve (screening) analysis. Like all petroleum products, sampling is, or can be, a major issue. If not performed correctly and poor sampling is the result, erroneous and very misleading data can be produced by the analytical method of choice. For this reason, reference is made to standard procedures such as the Standard Practice for Collection and Preparation of Coke Samples for Laboratory Analysis (ASTM D346) and the Standards Test Method for the Sieve Analysis of Coke (ASTM D293). 

Several attribntes distingnish process analytical methods from classic laboratory analysis. Most prominent are those differences that refer to the direcmess of the analysis in the process versns that of one in a controlled laboratory environment ... 

The quality plan defines the inputs and outputs of any laboratory process. For example, the quality plans refer to the analytical methods, the irrstnrments and laboratory equipment that are used for the analysis, the characteristics of the analysis results etc. All laboratory processes (e g. analytical methods) and laboratory products (e g. analytical resrrlts) should be subject to verification and validation to ensme that they are fit for the ptrrpose. The acceptance criteria should be defined and records should always be kept as evidence of meeting the requirements. 

Readers may note three imique features in this text. First, there is a substantial discussion of chemical reactions of all elements and many of their compounds, a practice abandoned nowadays by most modem reference and handbooks. Second, analytical methods are presented for identification and measurement of practically all entries. In many instances, the method is based on my own research and experience. Third, a preparation method is given for all entries. For most compoimds, more than one preparative method is presented, covering both laboratory and commercial production. Also, a brief history of the discovery and early production of selected elements is presented to serve as backgroimd against which modern methods may be judged and historical perspective maintained. 

Analytical method validation forms the first level of QA in the laboratory. Analytical quality assurance (AQA) is the complete set of measures a laboratory must undertake to ensure that it is able to achieve high-quality data continuously. Besides the use of validation and/or standardized methods, these measures are effective IQC procedures (use of reference materials, control charts, etc.), with participation in proficiency testing schemes and accreditation to an international standard, normally ISO/IEC 17025 [4]. Method validation and the different aspects of QA form the subject of Section 8.2.3. 

The different levels in Figure 6 represent the different measures a laboratory must undertake in order to ensure that it is qualified and competent to perform analytical measurements which satisfy their agreed requirements. A laboratory must be capable of providing analytical data of the required quality. The agreed requirement of an analytical method and the required quality of an analytical result refer to the fitness for purpose of the method [4,8,15]. 

One or more of these bias components are encountered when analyzing RMs. In general, RMs are divided into certified RMs (CRMs, either pure substances/solu-tions or matrix CRMs) and (noncertified) laboratory RMs (LRMs), also called QC samples [89]. CRMs can address all aspects of bias (method, laboratory, and run bias) they are defined with a statement of uncertainty and traceable to international standards. Therefore, CRMs are considered useful tools to achieve traceability in analytical measurements, to calibrat equipment and methods (in certain cases), to monitor laboratory performance, to validate methods, and to allow comparison of methods [4, 15, 30]. However, the use of CRMs does not necessarely guarantee trueness of the results. The best way to assess bias practically is by replicate analysis of samples with known concentrations such as reference materials (see also Section 8.2.2). The ideal reference material is a matrix CRM, as this is very similar to the samples of interest (the latter is called matrix matching). A correct result obtained with a matrix CRM, however, does not guarantee that the results of unknown samples with other matrix compositions will be correct [4, 89]. 

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. 

The standard recognizes (section 5.6.1) that the traceability requirements should apply to aspects of the method that have a significant influence on the result of the measurement. For an analytical chemistry laboratory, as well as for the reference materials used for calibrating the response of an instrument, balances will need to be calibrated from time to time, and appropriate certification of the traceability of glassware and thermometers must be available. 

During the 1990 Washington Conference on Analytical Methods Validation Bioavailability, Bioequivalence and Pharmacokinetic Studies [1], parameters that should be used for method validation were defined. The final report of this conference is considered the most comprehensive document on the validation of bioanalytical methods. Many multinational pharmaceutical companies and contract research organizations contributed to its final draft. This scientific meeting was sponsored by the American Association of Pharmaceutical Scientists (AAPS), the Association of Official Analytical Chemists (AOAC), and the U.S. Food and Drug Administration (FDA). The conference report has been used as a reference by bioanalytical laboratories and regulatory agencies worldwide. 

Huber has published two validation reference books for the analytical laboratory [7,8]. The first one covers all validation aspects of an analytical laboratory, including equipment, analytical methods, reference compounds, and personnel qualification. The second covers the validation of computerized and networked systems. 

The Nordic Committee on Food Analysis has published a guideline on the Validation of Chemical Analytical Methods which differentiates between external validation work carried out on published methods and that work required to transfer it into the working laboratory to confirm its suitability for use. Table 20 is adapted from this document. This document is most easily accessed from a recently published book If certified reference materials are available they should be used to confirm the verification of trueness. These guidelines could also apply to intra-laboratory training programmes. 

Interlaboratory Quality Control. In addition to the mandatory quality control practices just outlined, the laboratory is encouraged to participate in interlaboratory programs such as relevant performance evaluation (PE) studies, analysis of standard reference materials, and split sample analyses. Participation in interlaboratory analytical method validation studies is also encouraged. 

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