Quality control reference materials

For every batch of 20-30 samples a quality control reference material is analysed - either NIST SRM 2711 or CYP-A. 

See also Air Analysis Sampling. Extraction Solvent Extraction Multistage Countercurrent Distribution Supercritical Fluid Extraction. Gas Chromatography Multidimensional Techniques. Mass Spectrometry Time-of-Flight. Quality Assurance Quality Control Reference Materials. Water Analysis Overview. 

Purity Determination Stabiiity Testing. Process Analysis Overview. Quality Assurance Quality Control Reference Materials Production of Reference Materials. Supercritical Fluid Chromatography Applications. 

See also Atomic Absorption Spectrometry Principles and Instrumentation. Chemiluminescence Overview. Chromatography Overview. Flow Injection Analysis Principles Instrumentation. Ion-Selective Electrodes Overview. Quality Assurance Quality Control Reference Materials. Sample Handling Sample Preservation. Sampling Theory. Water Analysis Overview Organic Compounds. Water Determination. 

Noil, 5—Highly precise robotic or scmi-uulomatcd sample preparation systems are available commercially. These systems may be used to prepare calibration standards and samples for analyses provided that the results for the quality control reference material (Section 10) are met when prepared using the automated systems. 

The GC/MS system must be recalibrated whenever results of the quality control reference material do not agree within the tolerance levels specified in 10.1. 

Analyze the quality control reference materials before every batch of samples. Bracket the samples with the reference material. If the reference material does not meet the specification in 10.1, the samples analyzed immediately preceding the reference material are considered suspect and should be rerun. Retming of the mass spectrometer and drift with time may require recalibration of the GC/MS system (see Section 9). 

Afler the calibration has been completed, prepare the quality control reference material outlined in Table 8. Analyze the reference material as described in the sample preparation procedure below. The individual aromatic and total aromatics values obtained must agree within 5 % relative of the values in the prepared reference material (for example, benzene 1.0 0.05). If the individual values are outside the specified range verify calibration and instrument parameters, accuracy of the preparation of quality control reference material, and so forth. Do NOT analyze samples without meeting the quality control specifications. 

Whilst nothing can improve upon the disadvantage of low molar absorption coefficients, instrumental designs and improvements with ratio recording and FT-IR instruments have virtually overcome the accuracy and instrumental limitations referred to in (b) and (c) above. As a result, quantitative infrared procedures are now much more widely used and are frequently applied in quality control and materials investigations. Applications fall into several distinct groups ... 

Unfortunately these and other existing quality control procedures do not answer aU problems. There remains a clear need for development of PCR reference materials that win provide information both on quality and quantity levels. For quality the reference materials should be host-specific and PCR primers, for positive control, may correspond to host specific house keeping genes e.g. b-actin. For quantitative analysis, fluorescence dyes in specific primers might be used in order to measure accurately the amount of DNA present. Such practices, and other as yet un-realized procedures, will be needed to achieve reliable results in the quantification of DNA analysis. 

The most extensive effort involves quality assurance. CDC provides common quality control (QC) materials and all members use standardized QC procedures. In addition, CDC regularly surveys the CRMLN laboratories to ensure they meet the required criteria. Initially, surveys were conducted monthly however, as the laboratories gained experience and performance improved, the survey schedule was changed to bimonthly. These surveys use CDC frozen serum secondary reference materials that have been prepared using NCCLS C37-A protocol [28], TC surveys include three levels analyzed in duplicate in two runs. HDLC surveys include four levels analyzed in duplicate in four runs. As an additional check on the quantitative step of the HDLC method, a low-total cholesterol material with cholesterol concentration <100 mg/dl is added to the TC survey. LDLC surveys include four levels analyzed in quadruplicate in four runs. 

The role and use of reference materials are in principle well known, in particular for Certified Reference Materials (CRMs) used as calibration materials or matrix materials representing - as far as possible - real matrices used for the verification of the measurement process, or (not certified) laboratory reference materials (LRMs also known as quality control (QC) materials) used, for example, in interlaboratory studies or in the maintenance of internal quality control (control charts). Examples of reference materials relevant to WFD monitoring (water, sediment and biota) are described in the literature (Quevauviller, 1994 Quevauviller and Maier, 1999). 

Quality control refers to that part of good pharmaceutical manufacturing practices concerned with the operations of verification of quality levels acceptance or rejection of raw materials, acceptance or rejection of semifinished or finished products, estimation of the stability of products, examination of returned products and supervision of retained sample stores. 

Technology (NIST), formerly the National Bureau of Standards founded in 1918, is responsible for maintaining both scientific and commercial metrology in the United States. Its mission is to promote American innovation and competitiveness and supplies industry, academia and government with certified standard reference materials, including documentation for procedures, quality control, and materials for calibration. The German Institute for Standards (DIN) was founded in 1917 while in the United Kingdom the BSI was formed in 1901. 

In the development of new analytical methods, the use of well-characterized reference materials can be invaluable in comparing measurement technologies, assessing potential sources of bias, and in method validation. Reference materials are also useful as controls for quality assurance. Reference materials produced by national metrology institutes are usually classified as certified reference materials (CRMs) ... 

The quality control of galvanic anodes is reduced mainly to the analytical control of the chemical composition of the alloy, to the quality and coating of the support, to an adequate joint between support and anode material, as well as to restricting the weight and size of the anode. The standards in Refs. 6, 7, 22, 27, 31 refer to magnesium and zinc anodes. Corresponding specifications for aluminum anodes do not exist. In addition, the lowest values of the rest potentials are also given [16]. The analytical data represent the minimum requirements, which are usually exceeded. 

There will be a continued need for enantiospecific methods of preparation and analysis, not only to ensure the quality of the final drug substance and reference materials, but also to control starting materials used for their manufacture, and key intermediates during synthesis. Likewise, specific and sensitive bioanalytical methods will be required to follow the fate of individual enantiomers after their administration. 

In a modern industrialised society the analytical chemist has a very important role to play. Thus most manufacturing industries rely upon both qualitative and quantitative chemical analysis to ensure that the raw materials used meet certain specifications, and also to check the quality of the final product. The examination of raw materials is carried out to ensure that there are no unusual substances present which might be deleterious to the manufacturing process or appear as a harmful impurity in the final product. Further, since the value of the raw material may be governed by the amount of the required ingredient which it contains, a quantitative analysis is performed to establish the proportion of the essential component this procedure is often referred to as assaying. The final manufactured product is subject to quality control to ensure that its essential components are present within a pre-determined range of composition, whilst impurities do not exceed certain specified limits. The semiconductor industry is an example of an industry whose very existence is dependent upon very accurate determination of substances present in extremely minute quantities. 

In addition to the requirements regarding traceability of measurement results, the measurement methods employed should represent "state-of-the-art in the particular field. Failing to do so would lead to a reference material with an uncertainty that has become too large to serve as a quality control. The better the methods perform in terms of uncertainty and traceability, the better the reference material will serve the interests of the (potential) users. 

Chau ASY, Caeron J and Lee H-B (1979) Analytical reference materials. II. Preparation and sample integrity of homogeneous fortified wet sediment for polychlorinated hiphenyl quality control studies. J Assoc Off Anal Chem 62 1312-1314. 

Griepink B, Maier EA, Quevauvilier P and Muntau H (1991) Certified reference materials for the quality control of analysis in the environment. Fresenius Anal Chem 339 599-603. 

Analytical Quality Control Services (1998) AQCS Intercomparison Runs Reference Materials 1998-1999. International Atomic Energy Agency, Vienna. 

Benoliel MJ. Quevauviller P, Rodrigues E, Andrade ME, Cavaco MA, Cortez L (1997) Certification of reference materials for quality control of major element determinations in ground-water Part i Feasibility study, fresenius J Anal Chem 358 574-580. 

Ihnat M (1988c) Biological reference materials for quality control. In McKenzie HA, Smythe LE, eds. Quantitative Trace Analysis of Biological Materials, pp 331-351. Elsevier Science Publishers, Amsterdam. 

Ihnat M (1994) Development of a new series of agricultural/food reference materials for analytical quality control of elemental determinations. J AOAC Inti 77 1605-1627. 

Morabito R, Muntau H, Cofino W, Quevauviller Ph 1999) A new mussel certified reference material (CRM 477) for the quality control of butyltin determination in the marine environment. J Environ Monit 1 75-82. 

Quevauviller Ph, Kramer KJM, Vinhas T (1996) Certified reference material for the quality control of cadmium, copper, nickel and zinc determination in estuarine water (CRM 505). Fresenius J Anal Chem 354 397-404. 

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