Round robin exercises

The corrected excitation and emission spectra for quinine sulfate from previous work (17) and from a round-robin exercise (11) are given In Figure 1. The coefficients of variation are also given at each point to Indicate the amount of agreement In measured values from the ten laboratories participating In the round-robin exercise. 

It is important that round-robin exercises be organized using materials and analytes relevant to the ocean sciences and that laboratories be encouraged to participate, even at an early stage in their experience with the relevant analytical techniques. 

A substantial impetus for improvements in analytical quality control within individual laboratories comes from participation in round-robin exercises in which participating laboratories independently analyze samples of a particular test material for specified analytes. It is important... 

Most methods (electron probe microanalysis, micro-Auger, secondary ion mass spectrometry) cannot be considered as really accurate methods except when applied to quite simple systems. Their application relies on the use of CRMs but these are, with very few exceptions, not available. The reason for the lack of CRMs is the absence of any reliable methods of microanalysis. None of the limited range of primary methods is applicable for the analysis of a solid at a microscopical level. The world of microanalysis is badly in need of at least one method which is able to act as a reference for the other techniques and to link RMs or round-robin exercises to the SI units [22],... 

Below, sample preparation methods of various types of samples will be briefly discussed. The description is based on sample matrices and is not intended to be comprehensive. Sample preparation techniques originally developed for a specific sample type may, however, also be successfully used for another sample matrix. As a result of international round-robin exercises in the field of verification analysis, a number of recommended operating procedures (ROPs) has been published and tested (34). Further testing of these procedures has taken place since 1995 during proficiency testing under the auspices of the Technical Secretariat of the OPCW. These procedures were developed for the analysis of samples with unknown analytes, in order to allow the identification of as many different chemicals of CWC interest as possible. This approach implies that these procedures can be further optimized in cases... 

The development of CE analytical methods for CW-related compounds has been directed primarily toward the analysis of these compounds in environmental matrices such as soil and water. These methods have been used in the analysis of samples distributed as part of the interlaboratory comparisons exercises, the so-called round-robin exercises coordinated by Finland, and more recently, the OPCW Laboratory Proficiency Testing. 

Even in those cases where an aiialysis is qualitative, quantitative measures are employed in the processes associated with signal acquisition, data extraction, and data processing. The comparison of, say, a sample s infrared spectrum with a set of standard spectra contained in a pre-recorded database involves some quantitative measure of similarity in order to find and identify the best match. Differences in spectrometer performance, sample preparation methods, and the variability in sample composition due to impurities will all serve to make an exact match extremely unlikely. In quantitative analysis the variability in results may be even more evident. Within-laboratory tests amongst staff and inter-laboratory round-robin exercises often demonstrate the far from perfect nature of practical quantitative analysis. These experiments serve to confirm the need for analysts to appreciate the source of observed differences and to understand how such errors can be treated to obtain meaningful conclusions from the analysis. 

Two interlaboratory studies were organised prior to the certification campaign. The first one dealt with the analysis of artificial seawater and the second exercise concerned the analyses of natural and spiked seawater. The results obtained for Cd, Cu, Pb and Zn are compared in Table 8.23. The CV between all the laboratories appeared to be quite high in the second round-robin exercise. However, the participation in such intercomparison combined with critical discussions of methods and results was found to be a most useful tool in obtaining a high level of accuracy (which is reflected in the... 

The method using U20g as fuse and attacking reagent in pyrohydrolysis was verified in many round-robin exercises. In this certification, a temperature of 1250 C was applied and a volume of water of 500 mL was used for a duration of the treatment of about 60 min which was considered to be acceptable. 

Owing to the high spread of results obtained for the MeHg determinations in the extracts, it was decided to organise a third round-robin exercise to improve the situation. 

The CVs between laboratories (Table 12.6) showed, however, that the state of the art improved in comparison with the second round-robin exercise (11.3% instead of 16.6% for the raw extract, and 8.8% instead of 17.4% for the spiked raw extract). 

From the beginning it was clear that it was essential to examine each step criticaUy in the methods for MeHg determination. To do so, several series of samples were prepared to (i) test the detection methods with solutions of known composition of Hg compounds, (ii) test the performance of the separation using cleaned extracts, (iii) verify the clean-up procedures by performing analysis of raw extracts and (iv) test the total analytical procedure by analyzing real samples. These evaluations were carried out in three intercomparisons, the first one of which started in 1987 (simple solutions), the second one in 1988 (cleaned and raw extracts) and the third round-robin exercise was carried out in 1989 (extracts and real samples) [81]. Youden plots [83] in some cases supported the technical conclusions. 

Tittarelli, P., Round Robin Exercise for Sulfur Test Methods for EN 228 and EN 590 Fuel Specifications, CEN/TC 19/WG 27, April 2000. 

Sulphur Methods for EN228 and EN590 Fuel Specifications, CEN/TC19 WG27 Report on Round Robin Exercise, May 2000. 

Guidelines and recommendations for this purpose are described in an ISO Standard (35). The analytical procedures chosen are usually tested in a round-robin exercise to determine repeatability and reproducibility criteria before final approval and adoption as a standard method. 

Results from IAEA Round Robin Exercise on VVWER-440 RPV weld material Irradiation, annealment and re-embrittlement. 

Regarding the neutron fluence value at the time of annealing, no substantial effects were found. Residual embrittlement, as well as the rate of further re-embrittlement, is practically independent of this neutron fluence. The lateral (horizontal) shift approach was also confirmed in the IAEA Round Robin Exercise on radiation embrittlement of WWER-440 weld metal, as shown in Rg. 5.16. The microstructure investigation results demonstrate that copper clusters, which are formed in material under primary irradiation, are not recovered during annealing to a structure of solid solution such as that in the unirradiated state. 

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