Isolation of the Chlordane Compounds U82, MC5, MC7, and MC8 from Technical Chlordane by HPLC Including Structure Elucidation of U82 and Determination of ECD and NICI-MS Response Factors

• Published in: Environmental science & technology 1999-05, Vol.33 (9), p.1353-1358
• Main Authors: Karlsson, Heidi, Oehme, Michael, Scherer, Gerd
• Format: Article
• Language: English
• Subjects: chemical structure; electron capture detection; isomers; negative ion chemical ionization mass spectrometry; pollutants; spectral analysis
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es9809962

A combination of reversed-phase and normal-phase HPLC techniques allowed to isolate amounts in the order of 5−300 μg of the octachloro isomers U82, MC5, MC7, and MC8 from technical chlordane. Their identity was confirmed by capillary gas chromatography mass spectrometry on two stationary phases. 1H NMR and mass spectrometry allowed to elucidate the structure of U82 as 1-exo,2-endo,3-exo,4,5,6,8,8-octachloro-3a,7,7a-tetrahydro-4,7-methanoindane. This chiral isomer is the most abundant octachloro isomer in humans and the only one identified so far having an H atom at the bridge head atom C7. Response factors were determined for negative ion chemical ionization mass spectrometry (NICI-MS) and deviated by a factor of 1.6−2.6 from those for cis/trans-chlordane. For electron capture detection (ECD), only MC5 showed a significant difference. Beside the missing Cl atom at C7, the structure of U82 is identical to that of trans-nonachlor, which shows a high accumulation and slow metabolism in mammals. This might be the reason for a similar behavior of U82.