本研究開發了一種簡單、靈敏且對環境友好的方法以檢測水樣中 九種 parabens 防腐劑的殘留。此方法是以超音波輔助疏水性深共熔溶 劑 乳 化 微 萃 取 法 ( Deep eutectic solvent-based ultrasound- assisted emulsification microextraction , DES-USAEME ) 從水樣中萃取待測物，再透過超高效液相層析串聯電灑游離（-）-四極桿飛行時間質譜儀（UHPLC-ESI（-）-QTOF-MS）進行測定。選擇莫耳比為 2:1 的薄荷醇（作為氫受體）和十二烷酸（作為氫供體）的疏水性深共熔溶劑作為萃取劑，因其較便宜、容易在室溫下合成且對環境友善。本研究透過 Box-Behnken Design 實驗設計法（BBD）的多變量實驗設計及反應曲面法和多變量分析（ANOVA）進行各項因子的最佳化。 所得出的最佳條件為：在離心管中將 5 mL 水樣與 500 µL DES 混合。經過充分混和後加入 50 mg NaCl，並在 65°C 的超音波水浴中震盪 20 分鐘。再以 3000 rpm 離心 10 分鐘後，取出上層並用甲醇定溶至 500 µL，最後將 2 µL 提取物直接注入 UHPLC-QTOF-MS 中進行檢測。所開發方法的定量極限（LOQ）為 1 至 3.2 ng / mL。在 Intra-day及 Inter-day 的測試中，相對標準偏差 (RSD) 皆小於 10%，且回收率為82％至 99％，顯示此方法有良好的穩定性和再現性。最佳化後的 DES-USAEME 結合高選擇性和高靈敏度的 UHPLC-ESI（-）-QTOF-MS 已成功用於檢測水樣中的 parabens 防腐劑的微量殘留。;In this study, a simple, sensitive, and environmental-friendly method for determining the presence of nine paraben preservatives in water samples was developed. The target analytes were efficiently extracted from water samples using a deep eutectic solvent-based ultrasound- assisted emulsification microextraction (DES-USAEME), and their determination were then performed by the combination of ultrahigh- performance liquid chromatography and electrospray ionization (-)- quadrupole time-of-flight mass spectrometry (UHPLC-ESI(-)-QTOF-MS). Due to the cost and easy synthesis at room temperature, the hydrophobic DES of choice in this study was based on the mixture of menthol (as a hydrogen bond acceptor) and dodecanoic acid (as a corresponding hydrogen bond donor) at molar ratio of 2:1. The parameters of DES-USAEME were optimized by multivariate experimental design based on Box-Behnken design (BBD) plus with response surface design and analysis of variance (ANOVA). The optimal conditions were: 5 mL of water sample mixed with 500 µL of DES in a centrifuge tube. After vortex, 50 mg of NaCl were added and sonicated for 20 min in ultrasonic bath at 65 °C. After centrifugation at 3000 rpm for 10 min, the supernatant was collected and reconstituted with methanol to 500 μL, and then 2 μL of the extract was directly injected into UHPLC-QTOF-MS for detection. The limits of quantification (LOQs) of the developed method ranged from 1 to 3.2 ng/mL. High precisions were obtained for both intra- and inter-day analysis, and ranged from 1 to 10%.Satisfactory average spiked recovery ranged from 82 to 99%. Optimal DES- iv USAEME combined with highly selective and sensitive UHPLC-ESI(-)-QTOF-MS was successfully applied for the determination of selected parabens presenatives in various water samples at trace-level.
