Criteria for identification
WADA generally expects a capillary gas chromatographic retention time (or relative retention time) match between the sample and a reference standard, analysed using the same procedure in the same assay, of 1% or better and three diagnostic ions in the mass spectra to match to within 20% or better of the relative abundance of each ion. Although mass spectral library data may be useful in the early phase of substance identification, especially in generic screening procedures, they are not considered sufficiently reliable for the final identification. Similarly, published data are used more to assure reliability than directly for substance identification. Horseracing laboratories are required to have established and documented chromatographic and mass spectrometric criteria that the analyte of interest in the test sample must have in common with the reference material for identification purposes. To assist in this process, the racing industry, primarily through the efforts of the Association of Official Racing Chemists, has produced the guidelines Accreditation Require ments and Operating Criteria for Horseracing Laboratories, published by the International Laboratory Accreditation Co-operation (ILAC) (ILAC 1997). ILAC require that validation of methods by testing laboratories conform to ISO 17025 (ILAC 2002). WADA requires laboratories to be accredited to ISO 17025 (see Chapter 23) to be eligible for WADA accreditation, whereas animal-racing authorities only recommend laboratories to be accredited to ISO/IEC 17025 (ISO/IEC 2005). ISO 17025 (ISO/IEC 2005) requires traceability of measurements and in the sports fields, this is considered to be met, when identifying a prohibited substance, by the direct comparison with a reference material analysed in parallel or in series with the test sample. A reference stand ard is generally accepted as a chemical with a well-established structure. The material may be characterised structurally within the laboratory using appropriate techniques or validated against a certified reference material or by comparison with uncontroversial published data. A reference material may also be an isolate from a urine or blood sample after an authenticated administration, provided that the analytical data from it is sufficient to justify fully its identity as a metabolite from the substance administered. Chemical reference standards are often not available and hence there is the need to use authenticated administrations for comparison purposes. Many of the most common substances are now available with certificates of analysis, and thereby fully meet the generic traceability requirements of ISO 17025.
The required documentation for the analytical certificate is clearly set out in ISO 17025, but merely requires a statement as to the substance found. However, in some jurisdictions, analytical data must also be provided with the certificate, but this is rarely clearly specified and often gives grounds for claims by lawyers that data are being concealed; there is clearly a need for harmonisation of the requirements.
