Proficency Testing Scheme — History

During the first six years of its existence, the FIRMS Network organised inter-laboratory comparisons (ILCs) in-house, with the aim of harmonising and validating isotopic measurements to be used for forensic applications. In these ILCs, the samples distributed comprised materials of potential forensic interest such as packaging and pharmaceuticals to be analysed for δ2H, δ13C, δ15N and δ18O composition. Fifteen different materials were distributed over six exercises and as many as 30 international laboratories participated in these comparisons.

Two publications discuss the results from these inter-laboratory exercises:

Carter, JF; Hill, JC; Doyle, S & Lock, C, (2009) Results of four inter-laboratory comparisons provided by the Forensic Isotope Ratio Mass Spectrometry (FIRMS) network. Science & Justice, 49:127-137

Carter, JF & Fry, B (2013) Ensuring the reliability of stable isotope ratio data beyond the principle of identical treatment, Analytical and Bioanalytical Chemistry, 405, 2799-2814.


Without a fixed laboratory location, it would have been very difficult for FIRMS to be able to provide inter-laboratory comparisons accredited to ISO 17043 and be able to distribute the materials resulting from these exercises to the isotope community as reference materials. However a partnership with LGC Standards, and in particular their PT branch, was negotiated to overcome this. LGC PT is a major international provider of proficiency testing schemes which is accredited by United Kingdom Accreditation Service (UKAS) and runs 40 PT schemes involving the distribution of more than 250,000 samples every year. These schemes cover a diverse range of sectors including food, environmental, beverage, clinical and forensics. LGC PT also has a prominent role in the development of policy and guidance for proficiency testing.

A steering group consisting of representatives from LGC PT as well as the FIRMS Network was established for this new Proficiency Testing Scheme. This allows FIRMS to have an input into the material selection and results analysis, but LGC PT has taken over the administration of the scheme (distributing samples, collating results, data analysis, report drafting etc).


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