title: Compound-specific stable carbon isotope ratios (delta13C values) of the halogenated natural product 2,3,3',4,4',5,5'-heptachloro-1'-methyl-1,2'-bipyrrole (Q1).
abstract: Compound-specific isotope analysis using gas chromatography interfaced to isotope ratio mass spectrometry (GC/IRMS) was applied for the determination of delta13C values of the marine halogenated natural product 2,3,3',4,4',5,5'-heptachloro-1'-methyl-1,2'-bipyrrole (Q1). The delta13C value of a lab-made Q1 standard (-34.20 +/- 0.27 per thousand) was depleted in 13C by more than 11 per thousand relative to the residues of Q1 in dolphin blubber from Australia and skua liver from Antarctica. This clarified that the synthesized Q1 was not the source for Q1 in the biota samples. However, two Australian marine mammals showed a large variation in the delta13C value, which, in our experience, was implausible. Since the GC/IRMS system was connected to a conventional ion trap mass spectrometer by a post-column splitter, we were able to closely inspect the peak purity of Q1 in the respective samples. While the mass spectra of Q1 did not indicate any impurity, a fronting peak of PCB 101 was identified in one sample. This interference falsified the delta13C value of the respective sample. Once this sample was excluded, we found that the delta13C values of the remaining samples, i.e. liver of Antarctic brown skua (-21.47 +/- 1.47 per thousand) and blubber of Australian melon-headed whale (-22.80 +/- 0.33 per thousand), were in the same order. The standard deviation for Q1 was larger in the skua samples than in the standard and the whale blubber sample. This was due to lower amounts of skua sample available. It remained unclear if the Q1 residues originate from the same producer and location.
authors.affiliation: University of Hohenheim, Institute of Food Chemistry, Garbenstr. 28, D-70593 Stuttgart, Germany. w-vetter@uni-hohenheim.de
authors.forename: Walter
authors.initials: W
authors.lastname: Vetter
authors.forename: Gerd
authors.initials: G
authors.lastname: Gleixner
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D001685:Biological Factors / Q000737:chemistry*; D001717:Birds / Q000378:metabolism*; D002247:Carbon Isotopes / Q000737:chemistry; D004289:Dolphins / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006843:Hydrocarbons, Chlorinated / Q000032:analysis* / Q000737:chemistry*; D006846:Hydrocarbons, Halogenated / Q000032:analysis / Q000737:chemistry; D008099:Liver / Q000378:metabolism; D011758:Pyrroles / Q000032:analysis* / Q000737:chemistry*; D013045:Species Specificity
chemical_list: C503289:2,3,3',4,4',5,5'-heptachlor-1'-methyl-1,2'-bipyrrole; D001685:Biological Factors; D002247:Carbon Isotopes; D006843:Hydrocarbons, Chlorinated; D006846:Hydrocarbons, Halogenated; D011758:Pyrroles