Participating laboratories

The following laboratories participated in the certification campaigns on sediment CIBA-GEIGY, Bensheim (Germany) CID-CSIC, Departamento de 

Quimica Ambiental, Barcelona (Spain) ENEA, Divisione di Chimica Ambien-tale, Rome (Italy) Ministry for Agriculture, Fisheries and Food, Burnham-on-Crouch (United Kingdom) Universiteit Antwerp, Dept. Schiekunde, (Belgium) Universite de Bordeaux I, Lab. Photophysique et Phtotochimie Moleculaire, Talence (France) Universite de Pau, Lab. Chimie Analytique, Pau (France) University of Plymouth, Department of Environmental Sciences, Plymouth (United Kingdom) Universidad de Sevilla, Departamento de Quimica, Sevilla (Spain) 

Chemist, Teddington (United Kingdom) Landwirtschaftskammer Westfalen Lippe, Joseph-Konig-Institut, Munster (Germany) National Food Agency, Soborg (Denmark) Office de la Recherche Scientifique et Technique Outre-mer, Bondy (France). 

The following laboratories participated in the additional certification An Forais Taluntais, Wexford (Ireland) Bundesanstalt fur Materialforschung und Prtifung, Berlin (Germany) Centro di Radiochimica ed Analisis per Attivazione, Pavia (Italy) CNRS, Service Central d Analyse, Vernaison (France) Energieonderzoek Centrum Nederland, 

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At least two parameters are tested by the same laboratory on many nominally similar samples. In both cases, the simplest outcome is a round patch in the Youden plot, see Fig. 2.1, of points that signifies just noise, no correlation. .. no participating laboratory (or sample or point in time) is exceptional. On the other hand, an elliptical patch, especially if the slope deviates from what could be expected, shows that some effects are at work that need further investigation. After just noise, the... 

Peer review This involves setting up mechanisms for mutual review of dmg regulation systems. It serves as a means of external auditing, whereby the performance of one agency can be compared with that of others. Systems for international peer comparison of QC laboratories are one example. Proficiency tests are performed by the participating laboratories in such a way that each laboratory learns how well it is performing in comparison with the others. 

It is not necessary that participating laboratories be formally recognized, accredited or certified. Measurement of the property of interest should be completed by, or under the supervision of a technically competent manager qualified either in terms of suitable academic qualifications or relevant work experience. The participating laboratory should consider the analysis as a very special one, to be performed with special attention and all possible care, and not have it performed as part of its regular routine. 

Quality and traceability It is not required that participating laboratories are formally recognized, accredited or certified, provided that quality and trace-... 

The apphed pretreatment techniques were digestion with a combination of acids in the pressurized or atmospheric mode, programmed dry ashing, microwave digestion and irradiation with thermal neutrons. The analytical methods of final determination, at least four different for each element, covered all modern plasma techniques, various AAS modes, voltammetry, instrumental and radiochemical neutron activation analysis and isotope dilution MS. Each participating laboratory was requested to make a minimum of five independent rephcate determinations of each element on at least two different bottles on different days. Moreover, a series of different steps was undertaken in order to ensure that no substantial systematic errors were left undetected. 

BCR Analytical Approach for the Certification of PAHs in Natural Matrix CRMs Prior to the certification analyses for the CRM, each participating laboratory has to prepare standard solutions of the analytes to be determined from certified reference compounds (purity >99.0 %) to calibrate their instruments for response and response linearity (multiple point calibration), detection limit, and reproducibility. In the case of PAH measurements, reference compounds of certified purity are used as internal standards, which are not present at a detectable concentration in the matrix to be analyzed (e.g. indeno[i,2,3-cd]fluoranthene (CRM 267), 5-methylchrysene (CRM 081R), benzo[f ]chry-sene (CRM 046), picene (CRM 168), and/or phenanthrene-dio). 

External quality assessment schemes involve the distribution by the organizer, to participating laboratories, of aliquots from the same sample. Participants analyze the received specimen and send the results back to the organizer who prepares a report to summarize all data. 

Several collaborating laboratories (usually five participating laboratories) test the proposed substance using a variety of techniques. The relative reactivity or relative absorbance of the impurities present in a substance must be checked when a nonspecific assay method is employed, e.g. by colorimetry or ultraviolet spectrophotometry. It is particularly important to quantify the impurities when a selective assay is employed. In such a case, it is best to examine the proposed substance by as many methods as practicable, including, where possible, absolute methods. For acidic and basic substances, titration with alkali or acid is simple but other reactions which are known to be stoichiometric may be used. Phase solubility analysis and differential scanning calorimetry may also be employed in certain cases. 

The standard (four-parameter logistic) curve was prepared by the simplex method using absorbance values collected from each participating laboratory. 

The method trial process for NADA methods is different to the process for non-NADA methods. However, the validation protocol followed by the participating laboratories and the requirements for acceptance of the method are the same. The trial process also differs for determinative procedures and confirmatory procedures. Determinative procedures are evaluated using the multiple laboratory process, whereas the confirmatory method needs to be evaluated only in a single government laboratory. 

In the SMMT process, draft protocols are reviewed, and guidance provided to the sponsor to help ensure that the format and specifications are adequate. The protocol should be approved by CVM prior to the initiation of the method trial. Once the protocol and method description are acceptable to CVM, the methods are sent to the participating laboratories for review, and a method demonstration is scheduled. The method demonstration, attended by all participating laboratory analysts, involves review of the study protocol and method SOP and a laboratory demonstration of the method. Ideally, all revisions are completed by the end of the demonstration and the study protocol is signed. 

In the first phase, the performance of the instrumentation used for the method is demonstrated. Based on the analysis of standards, results from the participating laboratory should meet the system suitability requirements of the method. Successful completion of this phase will qualify the analyst, his or her equipment, and the laboratory for the trial. Failure in the first phase does not usually cause a method to fail the trial. However, it can slow the process. When a procedure fails during the first phase of a trial, the sponsor may need to write a cautionary note in the SOP discussing recommended or inadequate types of instruments. To correct the problem, the participating laboratory analyst can substitute equipment that gives adequate performance alternatively, the sponsor must find a different laboratory to participate in the trial. 

In the second phase, analysts in participating laboratories prepare and analyze a minimum of two conttol samples and two samples fortified at the proposed tolerance concenttation. This phase allows analysts to become familiar with the method before the analysis of samples that will be part of the method validation. Results from the second phase should demonsuate that the control samples are without interference and that the analysts in the participating laboratories can achieve acceptable recovery of analyte from the samples. It is not uncommon for an analyst to have to repeat the second phase several times before adequate results are obtained. Failure at this phase of the trial can cause a method to fail the Uial. Often the problems are related to a poorly written SOP that does not adequately describe the procedure. 

Following the completion of the trial, each participating contract laboratory provides a report of their results to the method trial Study Director. The government laboratory(ies) provide their results to the CVM method trial coordinator. The sponsor compiles the final results from participating laboratories into a summary report. A final version of the SOP is also provided that includes any revisions made because of observations made during the trial. The summary report, electronic and hard copies of all laboratory results, work sheets, and reports from each of the participating laboratories are sent to CVM for final review and acceptance. This should include electronic copies of all information necessary to verify all of the results. 

Guidelines for acceptability of NADA and non-NADA methods are the same. For the determinative procedure, the criteria described in Method Criteria for accuracy and precision are used to evaluate data generated at participating laboratories. There are no criteria for accuracy in the analysis of the incurred residue samples however, the overall data set is reviewed to see if there is general agreement between results obtained by contract laboratories and relative to the levels reported in the sponsor s laboratory. 

On occasion, results from one of the participating laboratories will fail to meet established acceptability criteria. In those cases, acceptance or rejection of the method is determined by the CVM based on overall method performance. For example, a method that has borderline but acceptable performance for both precision and accuracy at two of three participating laboratories and fails badly at a third laboratory would probably fail. A method that was a borderline failure in one laboratory but easily passed in the other laboratories could be accepted. 

Commodities in the OPMBS were assigned to laboratories based on the precept that no one laboratory should be overburdened. Thus, the most difficult commodities, based on information obtained during method development, were distributed among all four participating laboratories. 

Ruggedness can be determined by an interlaboratory study with a sufficient in > 8) participating laboratories following one and the same procedure as performed by different analysts, and using operational and environmental conditions that may differ but are still within the specified parameters of the assay [1, 41]. Detailed guidance for robustness and ruggedness testing is available [42, 43],... 

A proficiency testing scheme tests the performance of the participating laboratories whereas a collaborative study is used to test the performance of a particular method. 

Whittle [29] has described a thin-layer chromatographic method for the identification of hydrocarbon marker dyes in oil polluted waters. McLeod et al. [25] conducted interlaboratory comparisons of methods for determining traces of aliphatic and aromatic hydrocarbons in marine sediments. Agreement within a factor of 2 to 3 was obtained between the 12 participating laboratories. 

Participation in round-robin exercises offers a substantial impetus for improvements in analytical quality control within individual laboratories. During these events, participating laboratories individually analyze samples of a particular test material. Such exercises must be organized using materials and analytes relevant to the ocean sciences. Laboratories must be encouraged to participate, even if they are at an early stage in their experience with the relevant analytical techniques. 

With respect to stabilized ozone generators supplied and calibrated by the National Bureau of Standards, the participating laboratories obtained values that were about 15% lower on the average, at an ozone concentration of about 0.2 ppm. Therefore, although acceptable repeatability within and among laboratories can be achieved even with the potassium iodide bubbler method as a reference procedure, there are unpredictable variables inherent in this procedure that contraindicate its continued acceptance. 

The laboratory is also involved in quahty assessment, such as participation in an external quahty- control scheme (inter-laboratory comparison). Here, a variety of analytes in matrices such as hard water, soft water, and sludge are circulated to laboratories and the returned results are processed in a codified format so that each participating laboratory can only identify its own values. 

Collaborative Testing. A second approach to assessing accuracy, when no certified reference material is available, may be used in conjunction with analysis by independent methods and in-house materials. Sample exhanges with other laboratories can help establish the existence or absence of systematic errors in a method. Collaborative tests are most useful in this regard when some of the participating laboratories use different sample preparation and quantification. The utility of independent analysis methods and comparisons between destructive and non-destructive analysis is again emphasized here. 

If no suitable reference materials are available, the determination of trae-ness can also be carried out via inter-laboratoiy studies. The assigned value of the interlaboratoiy test sample, determined by the provider, is used as an estimate for the trae value. The organizers of such studies provide the participating laboratories with a report showing the score of each participant. 

Randomly selected sub-samples from a source of material are distributed simultaneously to participating laboratories for concurrent testing... 

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