Experiments directed to the compound-specific determination of the stable carbon isotope ratios of the Toxaphene congener B8-1413 in two technical mixtures and Antarctic Weddell seal

The carbon stable isotope ratio (δ13C value) of an environmentally-relevant Toxaphene congener in technical products and a biological sample from a remote region was in the focus of this work. For this reason, the major octachlorobornane residue of the multicomponent pesticide Toxaphene in biological samples, 2-endo,3-exo,5-endo,6-exo,8,8,10,10-octachlorobornane (B8-1413 or P26), was quantitatively enriched from two technical Toxaphene mixtures (Toxaphene and Melipax) in duplicates as well as from an Antarctic Weddell seal sample. Normal phase followed by reversed-phase high-performance liquid chromatography (HPLC) with three columns, respectively, coupled in series was used for this purpose. Four of the five fractionated samples fulfilled the requirement of an interference-free GC-elution for subsequent determination of the δ13C value by gas chromatography interfaced to an isotope ratio mass spectrometer (GC-IRMS). B8-1413 in Toxaphene (n = 1) was more depleted in 12C than in Melipax (n = 2), which agrees with previous results obtained for the entire mixtures. The B8-1413 isolate from a Weddell seal sample from the Antarctic showed a δ13C value between the two technical products. Although a source appointment to the one or the other product was not possible, this example indicates that long range transport to the Antarctic and by uptake and food-chain bioaccumulation of B8-1413 in seals did not change the δ13C value significantly. The observed differences in one duplicate sample indicate that statistic evaluation of samples used for isotope ratio MS measurements is an important issue.