Quality Assurance Aspects of GSR Analysis by SEM/EDX A Report of first-hand Experiences

摘要

Like many forensic science labs, the Belgian National Institute of Forensic Science (NICC) is involved in a Quality Assurance program aiming towards an ISO17025 Accreditation. Since last year, a project is underway in the GSR lab to validate the method used in the analysis of GSR samples acquired from the hands of suspects by SEM/EDX. The project is well underway, and is planned to lead to accreditation for this technique by the start of 2010. The presentation will discuss several aspects of the functioning of the lab that have to be addressed when preparing for this accreditation. Some of these issues and problems are so involved that separate sub-projects were defined in order to provide a manageable solution. The following topics will be treated in detail: definition of the scope of the accreditation, the validation of the SEM/EDX method with respect to : accuracy, precision, reproducibility and robustness, and the documentation of the Chain of Custody (CoC) of the samples and their storage. One specific sub-project that will be discussed is the study of contamination monitoring in different relevant locations of the lab. Finally, as we have recently acquired a new microscope, the technical criteria we used in the acquisition study will be presented with a focus on their relevance in a QA context. We feel this discussion is informative, both for labs that are pursuing a formal accreditation in the future, and those that work already in such a context and are in the process of acquiring new equipment.