Liquid chromatography–high-resolution mass spectrometry for identifying aqueous chlordecone hydrate dechlorinated transformation products formed by reaction with zero-valent iron

Abstract

Chlordecone (CLD) is a persistent toxic chlorinated pesticide which contaminates different ecosystems in French West Indies. A soil remediation process including zero-valent iron (ZVI) has produced promising results but failed to completely degrade CLD, and the analytical procedures used yielded little information on the transformation products. To fill these gaps, dechlorination of aqueous CLD by micrometric particles of ZVI has been investigated. Aliquots of water with 25% (v/v) of acetone spiked with 100 ppm CLD were taken at different times during a 30-day ZVI treatment and directly analysed by ultra-high-performance liquid chromatography in negative electrospray ionisation mode. CLD has been totally transformed after 14 days into 14 dechlorinated degradation products, including 9 isomeric compounds. The maximum chloride concentrations appearing in the medium represent 44% of that which would result from total dechlorination of CLD. The CLD transformation products identified by accurate mass measurements on an ultra-high-resolution Q-TOF mass spectrometer (Q-TOF-MS) were C₁₀H₃Cl₉O₂, C₁₀H₄Cl₈O₂, C₁₀H₅Cl₇O₂, C₁₀H₆Cl₆O₂ and C₁₀H₇Cl₅O₂. The results show the interest of LC-Q-TOF-MS for identifying transformation products of organic contaminants, and the effectiveness of micrometric ZVI particles to totally transform CLD into less chlorinated products.

Keywords:

• chlordecone
• Kepone
• reductive dechlorination
• zero-valent iron
• remediation
• ultra-high-resolution Q-TOF mass spectrometer

Acknowledgement

We thank the fruitful inputs of the anonymous referees.

Additional information

Funding

We acknowledge financial support provided by the Région Centre through the PhD fellowship of H. Belghit, by the projects ABACHLOR (supported by the DEMICHLORD concerted action initiated by INRA) and DEV CHLORDECONE (supported by BRGM research directorate on its internal budget), and by contract 2100598309 from the Ministry of Environment in the framework of the second National Chlordecone Action Plan (PNAC II).