Certification report

The most important document, accompanying a CRM is its certificate. ISO Guide 31 (1981) provides guidance for the establishment of certificates, labeling of CRMs, and certification reports. The certificate contains among other information the certified values and their respective uncertainties. As important as this information is the traceability statement, which defines to what references the CRM is traceable. Ideally, a CRM is traceable to a suitable (combination) of SI units. This is not always possible, so other stated references may appear here. Especially when certifying matrix reference materials, making the measurements traceable to SI does not imply that the CRM is traceable to SI as well. The steps necessary to transform the sample into a state that can be measured may have a serious impact on the traceability of the values, and thus on the traceability statement. 

Although labels and certificates are mandatory, certification reports are not. It also depend on the kind of RM, whether such a report is of any relevance. For instance, for the certification of gas mixtures, a certification report would not usually... 

Combination of the results from homogeneity testing, stability testing, and characterization and assembling an uncertainty statement Set-up of a certificate and, if appropriate, a certification report... 

Hesse did not find the foundation certificates any better than the dyes. Some certificates reported no tests for impurities or toxins which Hesse believed might be present. Some of the tests were inadequately sensitive or selective and many were not described in sufficient detail for duplication, if they were described at all. These certificates confirmed Hesse s fears that the industry had not been testing food dyes, and thus had no such set of tests. 

Hesse used the results reported in these certificates to begin to formulate the standards of purity which he would expect from a certifiable dye. If one certificate reported a particularly good result for, say, salt in a given dye, that would become the temporary minimum. He strove to secure for the country not some elusive threoretically pure dyes, but simply the best that industry could do if pushed, pushed as he had become convinced it had never been pushed before (33). 

In a note to chapter 5.10.2 of ISO/IEC 17025 details of the certificates/reports are specified, including the need to number each page and to give the total number of pages. 

The traceability of the reference value needs to be stated, but more importantly also demonstrated. In addition all the relevant information should be available in the certification report of the certified reference material. 

The final step of the prodnction is the marketing of the certified reference material and the distribntion. The most important item at this stage is the delivery of the certified reference material together with a detailed certification report with all the information relevant to the prodnction of the material as well as advice for the intended nse. The prodncer shonld also ensure that the certified reference material is... 

After vendor approval, quality control or quality assurance will reduce the number of tests and inspections of incoming goods as agreed in the certification report, e.g., one out of ten batches. 

Snell LM, Little BB, Knoll KA, Johnston WL (1992) Reliability of birth certificate reporting of congenital anomalies. Am J Perinatol, 9 219-222. 

This flexible approach to certification has also led us to take a more holistic view of RM production. Interlaboratory certification studies frequently highlight significant measurement problems, sometimes in a large number of participating laboratories. The tendency has been to make participants aware of this situation through the certification report but to take little other action. In future we aim to provide better value for money to both... 

I. Papadakis, Y. Aregbe, J. N(,rgaard, L. Van Nevel, P. D. P. Taylor, IMEP-12, Trace Elements in Water, Certification Report, EUR 19924 EN. http //www.irmm.jrc.be/ html/interlaboratory comparisons/imep/imep-12/IMEP12 certiEcationreport.pdf. 

The certificate should contain all information needed by users of the CRMs. The amount of detail included in a certificate depends on the nature of the material and the availability of a certification report. When a report is not supplied with a certificate, the amount of detail in the certificate should be large enough to allow the user make the right decision about whether the intended application of the CRM is correct. As an example, a full description of the adopted preparation and certification approach is included in the certificate of the CRMs for chemical... 

For reproducibility, a standard operating procedure should be adopted. Table 4.7 illustrates the reproducibility that can be attained using calibrated sieves. The data is taken from the certification report on reference materials of defined particle size issued by the Commission of the European Communities and refers to data generated by four laboratories with BCR 68. 

A definition of the equipment and methods to be used in assuring reliable test data and All test data, including instrument calibrations, testing and certification reports, and statistical justification. 

Value of g the required precision value a can be found in the certificate of the CRM itself a can be the uncertainty of the certified value when the same method as the certification method is used by the analyst. It can also come from the individual set of measurement values of one of the methods used in the interlaboratory certification study. In such a case, all individual data and the methods must be available from the certificate or the certification report. Such information is given in some CRM reports of BCR and is illustrated in Annex 3.1. The a can also be stated in a written standard as a minimal or target precision value to be obtained. Finally, a can also simply come from the laboratory itself which applied another method previously or with another instrument or from another laboratory experienced with the method, or it may be requested by a customer. Care must be taken in extrapolating a simply from another element or substance which is analysed in parallel using a multi-elemental or multiresidue methods, as these may not be comparable at all because of matrix effects etc. 

When having all individual data available from the certification report, the analyst may wish to have a closer insight into his performance in terms of comparison to the results achieved by a similar method used in the certification. In the case of materials certified for organic trace substances e.g. dioxins in fly ashes, where methods inevitably remain affected by small systematic errors, the uncertainty calculated from the set of data of the interlaboratory certification study may appear small compared to the spread of the accepted sets of data. The half-width of the 95% confidence interval of the set of data is used as uncertainty. The user can adapt the way of determining the value of Sq above. He may wish to replace the 95% confidence interval by a tolerance interval... 

Reconstitute one capsule in 10 ml peptone saline solution according to Annex E of the certification report. 

In Tables 1 and 2 the confidence limits (geometric mean CB,j fp/mr ) for the most frequently used combinations of capsules and replicates are given for MEYP and PEMBA respectively. For the spread plate technique on SBA only indicative values based on 4 sets of data are given in Chapter 8 of the certification report. 

More information on the use of this CRM can be found in Chapter 9 of the certification report. 

Outlying variances, e.g. as reflected by a Cochran test, do reveal that some sets of data suffer insufficient precision compared to the other sets obtained by other laboratories. Such sets affect the final uncertainty of the certified value but not the certified value as such. The technical discussion should address the reason why a set of data lacks precision (day to day bias ) or why in one laboratory the reproducibility figure is much lower than for the rest of the participants (repeatability figure rather than reproducibility, selection of data, not fully independent measurements etc.). Sets of data are rejected if the standard error of the mean (s/n) exceeds the standard deviation of the distribution of all the laboratory mean values. It must be stressed that BCR has accepted and even promoted alternative methods of measurements in some certification exercises, in order to back-up trueness of certified values. Finally, such methods may have shown that their precision was too poor and were not used to calculate the certified value and its uncertainty. In such cases the results are made available to the user of the CRM through the certification report. 

CERi II- ICATE AND CERTIFICATION REPORT 5.4.1. Information content... 

The entire certification work described in the BCR certification reports is examined by an independent group of experts so that all possible sources of unacceptable practice are detected and eliminated. The group of experts has strong metrological background... 

Guidelines for the production of BCR reference materials. Doc. BCR/48/93, Rart B Guidelines for the implementation of BCR certification projects, Rart C Instructions for the preparation of BCR certification reports, European Commission DG XII-C, rue de la Loi 20(), 1049 Brussels, Belgium (1994). 

The uncertainty is taken as the half-width of the 95% confidence interval of the mean given in (1). When the reference material is used to assess the performance of a method, the user should refer to the recommendations of the certification report. 

During the course of this certification some laboratories individually determined other elements. These results are given as indicative values in the certification report [2]. 

All data accepted after technical scrutiny were statistically evaluated none were rejected on a statistical basis. The certified values are given in Table 6.4. During the course of this certification some laboratories individually determined other elements. These results are given as indicative values in the certification report [4]. 

The certified values are presented in Table 6.14. Indicative values are given for information in the certification report [13]. 

Results of the different laboratories and methods were generally in good agreement and the technical discussion did not identify any particular bias. The certified values are listed in Table 6.17. Indicative values are given in the certification report [17]. 

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