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This study aimed to investigate the oxidative stress process and bioaccumulation the racemic/(−)-/(+)- 2,2ʹ,3,4ʹ,6-pentachlorobiphenyl were administered to adult zebrafish ( Danio rerio ) after prolonged exposure of 56-days uptake and 49-days depuration experiments. Stereoselective accumulation was observed in adult samples after racemic exposure as revealed by decreased enantiomer fractions. The two enantiomers of PCB91 accumulated at different rates with logBCF k values close to 3.7, suggesting that they were highly hazardous and persistent pollutants. Exposure to racemic/(−)-/(+)- PCB91 stereoselectively induced oxidative stress owing to changes in reactive oxygen species, malondialdehyde contents, antioxidant enzyme activities and gene expressions in brain and liver tissues. In addition, the stereoselective relationship between bioconcentration and oxidative stress were also presented in this study. Our findings might be helpful for elucidating the environmental risk of the two enantiomers of PCB91 that induce toxicity in aquatic organisms. [ABSTRACT FROM AUTHOR]

Mefentrifluconazole is a new chiral triazole fungicide with high efficiency and broad spectrum. Zebrafish embryos, larvae and adults were exposed to mefentrifluconazole racemate and enantiomers to investigate aquatic toxicity of mefentrifluconazole at the enantiomer level. Acute toxicity tests were conducted to determine the lethality of mefentrifluconazole. The developmental toxicity of mefentrifluconazole to embryos and larvae was also assessed during acute exposure. Besides, the growth parameters of adults were evaluated after 14 days' exposure. The 96-h LC 50 ranges of rac-, R-(−)- and S-(+)-mefentrifluconazole to all zebrafish life-stages were 0.753–1.198, 1.092–2.022 and 0.583–1.056 mg/L respectively. Larvae were the most sensitive to mefentrifluconazole in terms of lethality, followed by embryos and adults. During acute exposure, morphological deformities caused by mefentrifluconazole, such as yolk sac edema and pericardial edema in embryos, as well as pericardial edema and spinal curvature in larvae were discovered. Besides, mefentrifluconazole induced significant developmental defects, including inhibited heartbeat and reduced body length in both embryos and larvae. After 14 days' mefentrifluconazole exposure, severe growth inhibition in adult zebrafish was observed. Mefentrifluconazole shows enantioselective toxicity in all stages of zebrafish, and the order of toxicity is S-(+)-mefentrifluconazole > rac-mefentrifluconazole > R-(−)-mefentrifluconazole. Further study is required to explore the specific enantioselective mechanism. Our findings enable a better understanding of the potential risk of mefentrifluconazole to aquatic ecosystems at the enantiomer level. [Display omitted] • Mefentrifluconazole showed strong lethality to zebrafish. • Mefentrifluconazole induced severe developmental effects on multiple stages of zebrafish. • S-(+)-mefentrifluconazole exerted higher toxicity to zebrafish than R-(−)-mefentrifluconazole. [ABSTRACT FROM AUTHOR]

The enantiomeric separation of eight pesticides including bitertanol ( 1), diclobutrazol ( 2), fenbuconazole ( 3), triticonazole ( 4), imazalil ( 5), triapenthenol ( 6), ancymidol ( 7), and carfentrazone-ethyl ( 8) was achieved, using normal-phase high-performance on two cellulosed-based chiral columns. The effects of isopropanol composition from 2% to 30% in the mobile phase and column temperature from 5 to 40 °C were investigated. Satisfactory resolutions were obtained for bitertanol ( 1), triticonazole ( 4), imazalil ( 5) with the (+)-enantiomer eluted first and fenbuconazole ( 3) with the (-)-enantiomer eluted first on Lux Cellulose-2 and Lux Cellulose-3. (+)-Enantiomers of diclobutrazol ( 2) and triapenthenol ( 6) were first eluted on Lux Cellulose-2. (-)-Carfentrazone-ethyl ( 8) were eluted first on Lux Cellulose-2 and Lux Cellulose-3 with incomplete separation. Reversed elution orders were obtained for ancymidol (7). (+)-Ancymidol was first eluted on Lux Cellulose-2 while on Lux Cellulose-3 (-)-ancymidol was first eluted. The results of the elution order at different column temperatures suggested that column temperature did not affect the optical signals of the enantiomers. These results will be helpful to prepare and analyze individual enantiomers of chiral pesticides. Chirality 27:32-38, 2015. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

An enantioselective method was developed for the simultaneous detection of five chiral fungicides in soil, including fenbuconazole ( 1), tetraconazole ( 2), nuarimol ( 3), triticonazole ( 4), and simeconazole ( 5) by LC-MS/MS on a chiral stationary phase of cellulose tris-(3-chloro-4-methylphenylcarbamate) with a gradient elution. A new multifunctional filter was designed to simplify the QuEChERS (where QuEChERS is quick, easy, cheap, effective, rugged, and safe) method by simultaneous cleanup and filtration when the sample extracts were directly passed through it. Good linearities ( R2 > 0.9980) were obtained in the range 0.005-2.5 mg/L, and the recovery rates were 77.4-103.6% with RSDs of 0.7-12.2% for intraday precision and 1.2-11.0% for interday precision. The LODs and LOQs for all enantiomers were in the range 0.1-0.2 and 0.25-0.5 μg/kg, respectively. The analysis of the incubated soil suggests that this method is reliable and practical for the stereoselective detection of chiral fungicides. [ABSTRACT FROM AUTHOR]

Enantioselective accumulation of chiral polychlorinated biphenyls (PCBs) 91, 95, 136, 149, 176 and 183 was investigated in lotus plants ( Nelumbonucifera spp.) exposed to these chemicals via spiked sediment, to determine uptake and possible biotransformation for aquatic phytoremediation purposes. The concentrations of most PCBs were greatest in roots at 60 d (19.6 ± 1.51–70.6 ± 6.14 μg kg −1 ), but were greatest in stems and leaves at 120 d (25.3 ± 6.14–95.5 ± 19.4 μg kg −1 and 17.4 ± 4.41–70.4 ± 10.4 μg kg −1 , respectively). Total amounts were greatest at 120 d and significantly higher in roots than those in stems and in leaves (1457 ± 220–5852 ± 735 ng, 237 ± 47.1–902 ± 184 ng and 202 ± 60.3–802 ± 90.2 ng, respectively), but represented less than 0.51% of the total mass of PCBs added to sediments, indicating that lotus plants were unlikely to remove appreciable amounts of PCBs from contaminated sediments. Racemic PCB residues in sediment indicate no enantioselective biodegradation by sedimentary microbial consortia over the entire experiment. Preferential accumulation of the (−)-enantiomers of PCBs 91, 95 and 136 were observed in roots, stems and leaves, but non-enantioselective accumulation was observed for PCBs 149, 176 and 183. These results indicate that aquatic plants can accumulate PCBs enantioselectively via root uptake, possibly by biotransformation within plant tissues as observed for terrestrial plants. This is also the first report to identify optical rotation of the atropisomers of PCBs 91 and 95. [ABSTRACT FROM AUTHOR]