結合 MOF-808(Zr) 分散固相萃取與液相層析串聯質譜技術分析高極性農藥

Abstract

隨著農藥被過度濫用，以及其高毒性與生物累積性會對環境與生物造成危害，使得農藥殘留的問題逐漸被重視。而根據辛醇-水分配係數 (Kow) 可將農藥區分為疏水性及高極性農藥 (Highly polar pesticides)。由於高極性農藥具有兩性離子以及logP較小的特性，使其在定量方面具有一定的挑戰性。金屬有機骨架(MOF)作為新穎的吸附材料，具有高比表面積與高孔隙率的特性，因而被廣泛運用在吸附領域中。本研究使用MOF-303(Al) 與 MOF-808(Zr) 兩種MOF，並以X光粉末繞射進行表徵。接著將 MOF-808(Zr) 作為吸附劑運用至分散式固相萃取，MOF-303(Al) 則作為對照組。本研究使用Obelisc N管柱搭配高效能液相層析串聯式質譜儀 (HPLC-MS/MS) 對四種高極性農藥進行分析。以MOF作為吸附劑進行分散式固相萃取的優化。結果顯示在pH2的條件下 MOF-808(Zr) 能擁有最佳的吸附性能，吸附過程僅需使用10 mg的吸附劑用量並於5分鐘內完成吸附。因 Zr-OH 基團對於磷酸根的官能基具有高度親和力，使得 MOF-808(Zr) 擁有非常良好的吸附效率，結果顯示 MOF-808(Zr) 的表現比MOF-303(Al) 更為突出。本研究顯示 MOF-808(Zr) 可作為吸附劑應用於高極性農藥的前處理流程及後續分析，同時具有應用至食品或環境樣品的高度潛力。

The overusing of pesticide has led to growing concerns over environmental contamination and ecological risks. According to the octanol-water distribution coefficient (Kow) of pesticides, it can be categorized into hydrophobic pesticides and highly polar pesticides (HPP). The determination of HPP is very challenging due to their small logP and zwitterionic characteristics. Recently, metal-organic frameworks (MOFs) have attracted significant attention as promising adsorbent materials owing to their large specific surface area and uniform porosity. In this study, MOF-808(Zr) was synthesized and employed as an adsorbent in dispersive solid-phase extraction (dSPE) for the analysis of four highly polar pesticides (HPPs) including ethephon, glufosinate, glyphosate and their metabolites. The extracted analytes were subsequently quantified using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Optimized chromatographic separation of the four HPPs was achieved within 15 minutes using mixed-mode chromatography with a mobile phase consisting of acetonitrile and water, each modified with addition of formic acid. Optimization of the dSPE procedure revealed significantly enhanced adsorption efficiency at pH 2, with the process reaching completion within 5 minutes using only 10 mg of MOF-808(Zr). The superior adsorption performance of MOF-808(Zr) is attributed to the strong affinity between its Zr–OH groups and the phosphate groups present in the pesticide molecules. These findings highlight the potential of MOF-808(Zr) as a highly effective adsorbent for the efficient extraction and subsequent analysis of highly polar pesticides in environmental samples.