Detection of chlordecone by liquid chromatography with tandem mass spectrometry

A Novel Multi-ion Evaluation Scheme to Determine Stable Chlorine Isotope Ratios (37Cl/35Cl) of Chlordecone by LC-QTOF

Organochlorinated pesticides are highly persistent organic pollutants having important adverse effects in the environment. To study their fate, compound-specific isotope analysis (CSIA) may be used to investigate their degradation pathways and mechanisms but is currently limited to 13C isotope ratios. The assessment of 37Cl isotope ratios from mass spectra is complicated by the large number of isotopologues of polychlorinated compounds. For method development, chlordecone (C10Cl10O2H2; hydrate form), an organochlorine insecticide that led to severe contamination of soils and aquatic ecosystems of the French West Indies, was taken as a model analyte. Chlorine isotope analysis of chlordecone hydrate was evaluated using high-resolution liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS), enabling smooth ionization to detect the molecular ion. First, a new evaluation scheme is presented to correct for multiple isotope presence in polychlorinated compounds. The scheme is based on probability calculations of the most frequent isotopologues, distributions by binomial probability functions, and corrections for the presence of nonchlorine heavy isotopes. Second, mobile-phase modifiers, ionization energy (sampling cone tension) and scan time were optimized for accurate chlorine isotope ratios. Chlordecone standard samples were measured up to 10-fold and bracketed with a second chlordecone external standard. δ37Cl values were obtained after conversion to the SMOC scale by a two-point calibration. The robustness of the analysis method and evaluation scheme were tested and gave satisfactory results with standard errors (σm) of ±0.34‰ for precision and ±0.89‰ for long-term accuracy of chlorine isotope ratios of chlordecone hydrate. This work opens perspectives for applications of the C-Cl CSIA approach to investigate the fate of highly toxic and low reactive polychlorinated compounds in the environment.

Evidence for extensive anaerobic dechlorination and transformation of the pesticide chlordecone (C10Cl10O) by indigenous microbes in microcosms from Guadeloupe soil

The historic use of chlordecone (C₁₀Cl₁₀O) as a pesticide to control banana weevil infestations has resulted in pollution of large land areas in the French West Indies. Although currently banned, chlordecone persists because it adsorbs strongly to soil and its complex bis-homocubane structure is stable, particularly under aerobic conditions. Abiotic chemical transformation catalyzed by reduced vitamin B₁₂ has been shown to break down chlordecone by opening the cage structure to produce C9 polychloroindenes. More recently these C9 polychloroindenes were also observed as products of anaerobic microbiological transformation. To investigate the anaerobic biotransformation of chlordecone by microbes native to the French West Indies, microcosms were constructed anaerobically from chlordecone impacted Guadeloupe soil and sludge to mimic natural attenuation and eletron donor-stimulated reductive dechlorination. Original microcosms and transfers were incubated over a period of 8 years, during which they were repeatedly amended with chlordecone and electron donor (ethanol and acetone). Using LC-MS, chlordecone and degradation products were detected in all the biologically active microcosms. Observed products included monohydro-, dihydro- and trihydrochlordecone derivatives (C₁₀Cl_10-nO₂H_n; n = 1,2,3), as well as “open cage” C9 polychloroindene compounds (C₉Cl_5-nH_3+n n = 0,1,2) and C10 carboxylated polychloroindene derivatives (C₁₀Cl_4-nO₂H_4+n, n = 0–3). Products with as many as 9 chlorine atoms removed were detected. These products were not observed in sterile (poisoned) microcosms. Chlordecone concentrations decreased in active microcosms as concentrations of products increased, indicating that anaerobic dechlorination processes have occurred. The data enabled a crude estimation of partitioning coefficients between soil and water, showing that carboxylated intermediates sorb poorly and as a consequence may be flushed away, while polychlorinated indenes sorb strongly to soil. Microbial community analysis in microcosms revealed enrichment of anaerobic fermenting and acetogenic microbes possibly involved in anaerobic chlordecone biotransformation. It thus should be possible to stimuilate anaerobic dechlorination through donor amendment to contaminated soils, particularly as some metabolites (in particular pentachloroindene) were already detected in field samples as a result of intrinsic processes. Extensive dechlorination in the microcosms, with evidence for up to 9 Cl atoms removed from the parent molecule is game-changing, giving hope to the possibility of using bioremediation to reduce the impact of CLD contamination.

Exposure to the environmentally-persistent insecticide chlordecone induces detoxification genes and causes polyp bail-out in the coral P. damicornis

Marine ecosystems are both stressed and threatened by pesticides that are used on land. Nevertheless, research on the impact of pesticides on coral reefs and the underlying mechanisms is still in its infancy. The insecticide chlordecone is a persistent organic pollutant with carcinogenic effects in rats and mice. Chlordecone has been detected in diverse marine organisms in the Caribbean, but unexpectedly, also in French Polynesia. We combined transcriptomic and morphologic analyses of analyses the response of the coral Pocillopora damicornis to chlordecone stress. We compared chlordecone stress with thermal stress to determine a chlordecone-specific response. We found eight transcripts related to the P450-1A or P450-3A families that were specifically overexpressed in response to chlordecone. There was also sequential overexpression of transcripts involved in apoptosis and degradation of cellular matrix proteins. Finally, we report the first observation of chlordecone-induced P. damicornis polyp bail-out. Altogether, these results strongly suggest that apoptosis and expression of genes belonging to the cathepsin family are sequentially regulated processes leading to coenosarc dissociation and loss.

Localization and in situ absolute quantification of chlordecone in the mouse liver by MALDI imaging

Chlordecone is an organochlorine pesticide that was extensively used in the French West Indies to fight weevils in banana plantations from 1973 to 1993. This has led to a persistent pollution of the environment and to the contamination of the local population for several decades with effects demonstrated on human health. Chlordecone accumulates mainly in the liver where it is known to potentiate the action of hepatotoxic agents. However, there is currently no information on its in situ localization in the liver. We have thus evaluated a matrix-assisted laser desorption ionization (MALDI) imaging quantification method based on labeled normalization for the in situ localization and quantification of chlordecone. After validating the linearity and the reproducibility of this method, quantitative MALDI imaging was used to study the accumulation of chlordecone in the mouse liver. Our results revealed that normalized intensities measured by MALDI imaging could be first converted in quantitative units. These quantities appeared to be different from absolute quantities of chlordecone determined by gas chromatography (GC), but they were perfectly correlated (R(2) = 0.995). The equation of the corresponding correlation curve was thus efficiently used to convert quantities measured by MALDI imaging into absolute quantities. Our method combining labeled normalization and calibration with an orthogonal technique allowed the in situ absolute quantification of chlordecone by MALDI imaging. Finally, our results obtained on the pathological mouse liver illustrate the advantages of quantitative MALDI imaging which preserves information on in situ localization without radioactive labeling and with a simple sample preparation.

Detection and quantification of chlordecone in contaminated soils from the French West Indies by GC-MS using the 13C10-chlordecone stable isotope as a tracer

Chlordecone is an organochlorine insecticide that has been widely used to control banana weevil in the French West Indies. As a result of this intense use, up to 20,000 ha are contaminated by this insecticide in the French West Indies, and this causes environmental damage and health problems. A scenario of exposure was drawn by French authorities, based on land usage records. Many efforts have been made to monitor the occurrence of chlordecone and its main metabolites using different analytical methods, including GC, GC/MS, LC/MS, and NIRS. Although these different methods allow for the detection and quantification of chlordecone from soils, none of them estimate the bottleneck caused by extraction of this organochlorine from soils with high adsorption ability. In this study, we used (13)C10-chlordecone as a tracer to estimate chlordecone extraction yield and to quantify chlordecone in soil extracts based on the (13)C/(12)C isotope dilution. We report the optimization of (13)C10-chlordecone extraction from an Andosol. The method was found to be linear from 0.118 to 43 mg kg(-1) in the Andosol, with an instrumental detection limit estimated at 8.84 μg kg(-1). This method showed that chlordecone ranged from 35.4 down to 0.18 mg kg(-1) in Andosol, Nitisol, Ferralsol, and Fluvisol soil types. Traces of the metabolite β-monohydrochlordecone were detected in the Andosol, Nitisol, and Ferralsol soil samples. This last result indicates that this method could be useful to monitor the fate of chlordecone in soils of the French West Indies.

Validation of chlordecone analysis for native and remediated French West Indies soils with high organic matter content

An analytic method was developed and validated for the analysis of chlordecone in the three main types of French West Indies soils: Ferralsol, Andosol and Nitisol with and without the addition of Daramend® and compost amendment used in a remediation process. The method consists in analysis by gas chromatography coupled with triple quadrupole mass spectrometry after pressurised liquid extraction. The high natural content of organic matter in the soils coupled with the additional exogenous organic matter from the amendments tested lead to a complex extract. Trans-nonachlor was used as surrogate to correct the results for extraction efficiency, and (13)C chlordecone was added as internal standard to mimic as closely as possible the behaviour of chlordecone and suppress possible side effects during its analysis. The key parameters of the method (linearity, repeatability, interday precision, specificity, extraction efficiency and limit of quantification) were validated in accordance with the NF T 90-210 standard method. The limit of quantification is 0.03 mg/kg. Uncertainty (k = 2) was 40 % for concentrations lower than or equal to 1 mg/kg, and 30 % for concentrations greater than 1 mg/kg.