藉由混合模式液相層析質譜技術分析高極性農藥

Abstract

農藥廣泛地用於現今的農業當中，其伴隨的效益不僅可大幅降低人類的種植成本，更可以穩定且充足的產出作物以供應市場需求。然而，隨著農藥的使用不斷增加，食品安全問題以及檢驗方法的議題逐漸被重視。根據農藥的辛醇-水分配係數（Kow）可分為疏水性農藥和高極性農藥。高極性農藥因為其 logP 小且具有兩性離子特性，不易藉由逆相層析質譜進行分析。在本研究中，對益收生長素(Ethephon)、福賽得(Fosetyl-Al)、抑芽素(Maleic hydrazide)、嘉磷塞(Glyphosate)、固殺草(Glufosinate)及其代謝物等9種高極性農藥，使用混合模式管柱和醯胺管柱進行分離並使用液相層析串聯質譜法進行分析。藉由調整移動相的組成比例和層析梯度的改變來進行層析條件的優化。分別針對混合模式管柱和醯胺管柱進行探討，發現在移動相中加入甲酸對混合模式管柱和醯胺管柱至為重要。在優化後的層析條件下，混合模式管柱能夠有效地滯留9個高極性農藥並能在5分鐘內完成分離；而醯胺管柱亦可在10分鐘內完成。9種分析物的線性定量範圍為 0.5-100 ngmL-1，R2> 0.995。優化後的分析方法結合Quick Polar Pesticide (QuPPe) 方法未來可應用於食物樣品分析。

Pesticides are widely used in daily agriculture and the use of them is a major food safety concern. Considering the octanol-water distribution coefficient (Kow) of pesticides, they can be categorized to hydrophobic and highly polar pesticides (HPP). Highly polar pesticides are not easy to be analyzed by reverse phase LC-MS because their small logP and zwitterionic characteristics. In this study, nine HPP including ethephon, fosetyl-Al, maleic hydrazide, glyphosate, glufosinate and their metabolites were analyzed by mixed mode and amide liquid chromatography tandem mass spectrometry. The chromatographic conditions, including mobile phase compositions and gradients, for Obelisc N and amide columns were investigated and optimized for the separation of HPP. Addition of formic acid in the mobile phase was crucial for both Obelisc N and amide chromatography. With optimized conditions, all nine HPP were effectively retained and resolved by Obelisc N and amide columns in 15 min. The linear quantitative range of nine analytes was ranged 0.5-100 ngmL-1 with R2> 0.995. The optimized LC-MS combined with Quick Polar Pesticides methods (QuPPe) will be further applied for food samples using HPP.