On the significance of [M−HCl]− fragment ions in gas chromatography/electron capture negative ionization mass spectra of octachloro compounds of technical toxaphene

Abstract

À fragment ions in the ECNI mass spectra of octachlorobornanes was studied by monitoring m/z 374 in standards and technical toxaphene. This technique is an interesting tool to identify B8-1413 in complex mixtures. # 1998 John Wiley & Sons, Ltd. Received 23 December 1997; Revised 19 January 1998; Accepted 21 January 1998 Rapid Commun. Mass Spectrom. 12, 312-316 (1998 Toxaphene is one of the world's most produced synthetic pesticides derived from chlorinated hydrocarbons. Extensive use of toxaphene since the 1940s to combat insect pests in combination with its high persistence led to the fact that it is a major organochlorine contaminant in the biosphere. 1Due to its persistence and tendency to accumulate in lipids, toxaphene was banned in the 1970s in Western Europe and in the 1980s in Northern America. 2The complex technical mixture is synthesized by the exhaustive chlorination of camphene. Technical toxaphene contains several hundred compounds with C 10 À backbone, mostly polychlorinated bornanes. 3In 1992 two major recalcitrant compounds of technical toxaphene (CTTs) were isolated from blubber of marine mammals. 4,5 The year after these two compounds and further CTTs were gained as single standards 6 which are now commercially available.First congener specific analyses by GC/ECNI-MS, a high selective and sensitive technique for the quantitation of CTTs, showed that the response factors differed over a wide range 7-9 . CTTs with exclusive 2,2,5,5-substitution in the six-membered ring (C-1 to C-6) had a particularly low response factor. 8,9 This fact aggravates the quantitation of unknown peaks in samples in case of a biomatrix with a changed CTT-pattern such as seal blubber. In a recent publication isolation and structure elucidation of the persistent octachlorobornane 2-endo,3-exo,5-endo, 6-exo,8,8,9,10-octachlorobornane (B8-1412) was described. 10High abundance of B8-1412 was reported in seal blubber, cod livers, harbor porpoise and adelie penguin.10 However, the CTT-patterns of GC/ECNI-MS and GC/ECD chromatograms were significantly different. Particularly, the high abundance of B8-1412 in ECNI-MS was not so pronounced in ECD if compared with the major abundant octachlorobornane 2-endo,3-exo,5-endo,6-exo,8,8,10,10-octachlorobornane (B8-1413 or Parlar #26). Consequently, we studied the structure and response factors of B8-1412, B8-1413 (Parlar #26) and further octachloro-CTT standards and toxaphene. EXPERIMENTAL ChemicalsToxaphene was from Promochem (Wesel, Germany). CTT single standards and standard mixtures were from Dr. Ehrenstorfer (Augsburg, Germany) or Promochem (Wesel, Germany). Structures and abbreviations of the polychlorinated bornanes in this study are listed in Table 1. InstrumentalGC/ECNI-MS investigations were carried out with an HP 5989B MS Engine connected to an HP 5890 II plus gas chromatograph (Hewlett-Packard). Methane (quality 5.0; Linde, Germany) was used as CI reagent gas at an ion source pressure of 1.6 mbar. The system was optimized by manual tuning using m/z 312, m/z 414 and m/z 464 of...

A non-targeted gas chromatography/electron capture negative ionization mass spectrometry selected ion monitoring screening method for polyhalogenated compounds in environmental samples

“…(c)). Although the abundance of the compound in the SIM run was low, the combined mass spectrum even featured the [M–HCl] – fragment ion at m/z 374 next to [M–Cl] – at m/z 375 which was found to be characteristic for 2‐ endo ,3‐ exo ,5‐ endo ‐6‐ exo ‐8,8,10,10‐octachlorobornane (B8‐1413) . The combined isotope pattern very closely matched the theoretical values, even though the isotope pattern was constructed by the combination of fragmental isotope patterns from two runs.…”

Transport of chlorinated paraffins (CPs) from baking oven doors into the food

“…using single chain CP standards only, m / z values of chlorinated alkanes and alkenes can be distinguished by means of the monoisotopic peak of the [M−Cl] - fragment ions. From a related compound class, toxaphene, it was known that several congeners do also form [M−HCl−Cl] - fragment ions ( Vetter & Luckas, 1998 ), which interfere with COs bearing one Cl atom less. This type of fragmentation was also observed in the case of CPs ( Krätschmer et al, 2018 ).…”

Comparison of an Individual Congener Standard and a Technical Mixture for the Quantification of Toxaphene in Environmental Matrices by HRGC/ECNI-HRMS

“…At a resolving power of 11 000, no interferences with toxaphene ions were detected. The presence of naturally occurring 13 C results in other toxaphene fragments, such as [M -HCl] -, that can interfere with the [M -Cl]ions. The mass of 13 C is 4.5 mDa less than that of 12 CH, and a resolving power of ∼70 000 is needed to exclude any overlap between [M -HCl]and [M -Cl] -.…”

“…The presence of naturally occurring 13 C results in other toxaphene fragments, such as [M -HCl] -, that can interfere with the [M -Cl]ions. The mass of 13 C is 4.5 mDa less than that of 12 CH, and a resolving power of ∼70 000 is needed to exclude any overlap between [M -HCl]and [M -Cl] -. However, the maximum abundance of the [M -HCl]cluster relative to [M -Cl]is 20% (Table 3).…”

“…However, peak profiles in environmental samples often differ significantly from the industrial mixture, due to differing accumulation and decomposition behavior of individual congeners. The calculation of an average weighted response factor for individual congeners from the technical mixture can result in significant errors in quantitation because of the highly variable ECNIMS response of different toxaphene congeners (5,13,14). The magnitude of these errors would be expected to increase with decreasing similarity of an environmental sample to the technical mixture.…”