Summary of the FIRMS Inter-Laboratory Comparisons (ILC)

In the most recent FIRMS Network Inter-Laboratory Comparison of stable isotope measurements three test materials were distributed to 40 laboratories worldwide. The materials distributed were cellulose, ammonium nitrate and mammalian bone. Laboratories were requested to perform 10 measurements for each element (δ²H, δ¹³C, δ¹⁵N, δ¹⁸O) of each analyte. A method for the isolation of collagen from the bone was supplied. Laboratories were also invited to analyse the bone sample for lead and strontium isotopic composition.

Overall, 29 laboratories submitted results. Not every laboratory submitted ten replicate results and some only reported results for a selection of samples. A limited number of laboratories return results for lead or strontium isotopic composition and these data are not presented here. Please contact the FIRMS Network if you would like further information (firms@forensic-isotopes.org).

Detailed results for this study have been circulated to participating laboratories and will be made available on this website soon. Results for previous ILCs have been published in a special edition of the Forensic Science Society’s Journal, Science and Justice (doi:10.1016/j.scijus.2008.12.002) dedicated to forensic applications of IRMS.

ILC	Year	Materials	Elements
#1	2002	cane sugar & flour	δ13C, δ15N
#2	2004	phenacetin & polyethylene film	δ13C, δ15N, δ2H
#3	2006	horse hair  & paper x2	δ13C, δ15N, δ2H, δ18O
#4	2008	benzocaine & poly(ethylene glycol)	δ13C, δ15N, δ2H, δ18O
#5	2009	ammonium nitrate, cellulose and bone	δ13C, δ15N, δ2H, δ18O, Pb  Sr

Summary of the FIRMS Network ILCs to date.

 

ILC participants by element [blue = carbon, grey= nitrogen, red = hydrogen, black = oxygen]