畢芬寧光學異構物以對掌性高效液相層析儀分離及其水生生物毒性之研究   全文下載

Separation of Bifenthrin Enantiomers by Chiral HPLC and Determination of Their Toxicity to Aquatic Organism

本研究旨在利用高效能液相層析法（high performance liquid chromatography）分離除蟲菊殺蟲劑畢芬寧（bifenthrin）之對映異構物，並藉由收集分離後之異構物進一步探討畢芬寧對水生無脊椎生物水蚤（Daphnia pulex）及鯉魚（Cyprinus carpio）和吳郭魚（Tilapia spp.）之毒性，以瞭解其對映異構物與生物活性之間的關係。本實驗分離畢芬寧使用正己烷（n-hexane）/異丙醇（isopropanol）/乙醇（ethanol）（99.8/0.06/0.1）為移動相，滯留時間為20 min內，注射分析樣品濃度增為1000 mg/L（注入體積為20 μL）以增加收集之效率。本實驗方法可成功地將畢芬寧分離成二種異構物。收集分離後的單一光學異構物分別以Gc-Mass及旋光度計定性。畢芬寧二個光學異構物（-）-畢芬寧及（+）-畢芬寧的比旋光度[α]20365分別為-66.41°及+69.63°。氣相層析質譜分析方面，畢芬寧標準品以及其所分離的光學異構物主要質譜片段為m/z 115、m/z 141、m/z 165、m/z 181及m/z 422。水蚤及魚毒性之分析研究發現，以分離的兩種畢芬寧光學異構物測試得水蚤在8小時的半致死濃度（Lc50）分別為2.1 μg/L、28.9 μg/L。而96小時鯉魚Lc50，（-）-畢芬寧為0.99 μg/L、（+）-畢芬寧為2.08 μg/L。吳郭魚Lc50，（-）-畢芬寧為0.19 μg/L、（+）-畢芬寧為0.80 μg/L。結果顯示（-）-畢芬寧異構物對水蚤、鯉魚及吳郭魚均具有較高的毒性。本研究結果可提供畢芬寧光學異構物分離方法之建立與單一光學異構物對水生無脊椎生物及魚類之相關毒性資料之參考。

In this study, we separate enantiomers of bifenthrin, a pyrethroid insecticide, by using high performance liquid chromatography with a chiral stationary phase (CPS) column. Toxicity tests of bifenthrin enantiomers were performed with Daphnia (water flea, Daphnia pulex), tilapia fish (Tilapia spp.) and carp fish (Cyprinus carpio). Two enantiomers of bifenthrin were separated successfully by injecting 20 μL of bifenthrin 1000 mg/L standard solution into a Sumichiral OA-2500-I column. The mobile phase solvent system was composed of n-hexane, isopropanol, and ethanol in a ratio of 99.8/0.06/0.14, and the flow rate was 1.0 mL/min. Both enantiomers were eluted within 20 min. Two separated enantiomers, (-)-bifenthrin and (+)-bifenthrin, were identified by gas chromatography with mass spectrometry detector (GC-MSD) and polarimeter. Each enantiomer of bifenthrin and the standard bifenthrin solution showed the same fragmentation pattern spectrum. The fragment ions were m/z 115, m/z 141, m/z 165, m/z 181, and m/z 422. The specific rotations [α]20 365 of (-)-bifenthrin and (+)-bifenthrin were -66.41° and +69.63°, respectively. In the toxicity study, the LC50 (12 hr) of (-)-bifenthrin and (+)-bifenthrin for daphina were 2.1 μg/L and 28.9 μg/L, respectively. On the other hand, the result of fish toxicity indicated the LC50 (96 hr) of (-)-bifenthrin and (+)-bifenthrin for carp (C. carpio) were 0.99 and 2.08 μg/L, respectively, and for tilapia (Tilapia spp.) were 0.19 and 0.80 μg/L, respectively. The study of biological activity showed that the toxicity of (-)-bifenthrin was 10-fold greater than (+)-bifenthrin for Daphnia, and 2-fold greater for fish. This study provided improved methods for separating enantiomers of bifenthrin and assessing hazard of individual enantiomers toward non-target aquatic fauna.