CCQM-K21 Key Comparison – Determination of pp'-DDT in fish oil

Abstract

A key comparison on the determination of (pp'-dichlorodiphenyl) trichloroethane (pp'-DDT) in a fish oil matrix has been successfully completed. Nine NMIs participated in this key comparison and used the technique of isotope dilution gas-chromatography mass spectrometry (ID/GC/MS) for the determinations. Two samples (A and B) of fish oil were distributed to participants, each gravimetrically spiked with pp'-DDT. The KCRV for Sample A is 0.0743 ± 0.0020 µg g-1 and that of Sample B is 0.1655 ± 0.0014 µg g-1 of pp'-DDT in fish oil. The results for Sample A showed a RSD of 3.5%, the RSD for Sample B was within 1%. These results were an improvement over those of the corresponding pilot study (CCQM-P21), where at a mass fraction of pp'-DDT in fish oil of 0.311 µg g-1 the RSD was 2.6%. The compound pp'-DDT is a typical organochlorine pesticide and this key comparison has shown that NMIs have the ability to measure such compounds at levels typically found in the environment. The compound (pp'-dichlorodiphenyl) dichloroethylene (pp'-DDE), a metabolite of pp'-DDT, was the subject of a previous key comparison (CCQM-K5). The compound pp'-DDT is technically more challenging than that of pp'-DDE since it can decompose during the measurement procedure. Consequently the success of this key comparison, combined with that of CCQM-K5 demonstrates a broad measurement capability by NMIs for organochlorine compounds in the environment.Main text.To reach the main text of this paper, click on Final Report.Note that this text is that which appears in Appendix B of the BIPMkey comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the Mutual Recognition Arrangement (MRA).