Spiking chemicals

In the presence of an OPCW Laboratory representative, the sample preparation laboratory prepares the test samples and blanks, packs, and eventually dispatches a set to each participant in the test, including one to the evaluating laboratory and to the OPCW Laboratory. On receipt of the samples, the participants have two weeks to analyze the samples and to report their results to the OPCW Laboratory. In the same period, both the assisting laboratories and the OPCW Laboratory perform an analysis on the samples too these analyses are performed to confirm uniformity of the sample composition and to identify any impurities and degradation/reaction-products in the test samples that could be reported by the participants, in addition to the selected spiking chemicals. 

When the test period for all participants has expired, the spiking chemicals are announced and the participants reports are opened for evaluation. A copy of the reports is sent to the evaluating laboratory, which will evaluate the reports independently and in parallel with the OPCW Laboratory. Lor the purpose of evaluation, all reported chemicals, other than the spiking chemicals, are categorized. Categorization is based on the analysis results obtained by the assisting laboratories and by the OPCW Laboratory. The participants are scored on the basis of the outcome of the evaluation. 

The analysis and the reporting are the two core steps of participation in the scheme. In the attempt to identify all spiking chemicals in the analysis step, and to report them with acceptable analytical... 

The laboratory staff, that is, sample preparers, instrument operators, scientists, and synthesists, must join forces to analyze the samples, in order to identify the spiking chemicals with sufficient analytical evidence of acceptable/good quality. The work involves sample preparation, screening and analysis, data evaluation, and eventually making identification an example of an analysis strategy is described in Section 3.4. 

The data produced during the instrumental analysis must be filtered to obtain only data that (a) prove the identity of a spiking chemical, (b) are of good quality, and (c) meet the OPCW reporting requirements for the respective instrumental analysis (see reference 8), for inclusion in the final report. The initial filtering of data is performed by the instrument operators, checked by responsible scientists, and double-checked by the compiler of the report, in the scientific judgment step. 

Test Inspection Matrix sample Background material added Spiking chemicals Schedule... 

The overall performance of the each test participant is measured in the absolute number of spiking chemicals (Figure 14). The participants are named after the State Party in which the laboratory is located. The participants are listed in alphabetical order. The three bars represent ... 

Gray bar The number of spiking chemicals correctly identified and reported ... 

Figure 14. Overall performance of participants in proficiency tests 1 to 10, measured in the absolute number of spiking chemicals...

The sum of these three bars represents the total number of spiking chemicals a participant has been tested for during the first 10 proficiency tests, with a maximum of 72. These numbers depend on the frequency of participation as regular participants, and therefore differ from the other participants. The fact that not all participants were tested on exactly the same spiking chemicals plus taking into account the spread in the degree of difficulty of past proficiency tests (see Section 4.3) limits the extent to which the participants performances can be compared. The absolute numbers of... 

In the absence of library data, a laboratory must use its knowledge and experience in structure elucidation of CWC-related chemicals to find and identify chemicals of interest, and subsequently use its synthesis capabilities for confirmation. Structure elucidation is complicated by the presence of a background and by the low ppm level in which the spiking chemicals are present. 

A.6 N-Mustards Not used as spiking chemical in proficiency test 1 to 10 ... 

Prior to the evaluation, all test chemicals reported by the participants are categorized into (1) spiking chemicals, (2) chemicals, such as impurities, which are not used for scoring, (3) irrelevant chemicals, or (4) false positive chemicals. Spiking chemicals and non-scorable chemicals will undergo full evaluation, whereas the reporting of irrelevant and/or false positive chemicals immediately results in failure of the test. 

The evaluation is performed in accordance with the evaluation criteria specified in the quality system document QDOC/LAB/WI/PRO003 (8) Reported spiking chemicals that meet the criteria are accredited with +1 points, whereas spiking chemicals that do not (fully) meet the criteria, for any reason, are penalized with — 1 points. The latter penalty is also used for false negative results. 

The sum of all points scored eventually represents a laboratory s performance in a single proficiency test. The maximum achievable points, however, depends on the total number of spiking chemicals used. As this number varies from test to test, the points scored cannot be used to compare performances between laboratories participating in different proficiency tests. This comparison is achieved with the final letter scoring system, and is shown in Table 9. 

All spiking chemicals in the test have been identified and the identifications are supported with sufficient (analytical) data... 

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