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　　Abstract:

　　U.S. food imports have been increasing steadily for decades, intensifying the need for a rapid and sensitive screening technique. A method has been developed that uses foam disks to sample the surface of incoming produce. This work provides complimentary information to the extensive amount of published pesticide fragmentation data collected using LCMS systems (Sack et al. Journal of Agricultural and Food Chemistry, 59, 6383-6411, 2011; Mol et al. Analytical and Bioanalytical Chemistry, 403, 2891-2908, 2012). The disks are directly analyzed using transmission-mode direct analysis in real time (DART) ambient pressure desorption ionization coupled to a high resolution accurate mass-mass spectrometer (HRAM-MS). In order to provide more certainty in the identification of the pesticides detected, a library of accurate mass fragments and isotopes of the protonated parent molecular ion (the [M+H]+) has been developed. The HRAM-MS is equipped with a quadrupole mass filter, providing the capability of "data-dependent" fragmentation, as opposed to "all -ion" fragmentation (where all of the ions enter a collision chamber and are fragmented at once). A temperature gradient for the DART helium stream and multiple collision energies were employed to detect and fragment 164 pesticides of varying chemical classes, sizes, and polarities. The accurate mass information of precursor ([M+H]+ ion) and fragment ions is essential in correctly identifying chemical contaminants on the surface of imported produce. Additionally, the inclusion of isotopes of the [M+H]+ in the database adds another metric to the confirmation process. The fragmentation data were collected using a Q-Exactive mass spectrometer and were added to a database used to process data collected with an Exactive mass spectrometer, an instrument that is more readily available for this screening application. The commodities investigated range from smooth-skinned produce such as apples to rougher surfaces like broccoli. The minimal sample preparation and absence of chromatography has shortened the analysis time to about 15 min per sample, and the simplicity and robustness of the technique make it ideal for rapid screening.

　　摘要：

　　近數十年來美國國內進口食品的數量呈逐年穩步增長的趨勢，相對應地，對于能用于快速靈敏地篩查與確認的分析技術的渴求也也愈來愈強烈。我們報告一種利用泡沫(海綿)片對入口農產品進行表面采樣并隨即利用 DART-MS 快速分析和確證的方法。該方法提供了和已發表的含有大量的以 LCMS 系統收集到的農藥質譜裂解碎片數據(Sack et al. Journal of Agricultural and Food Chemistry, 59, 6383-6411, 2011; Mol et al. Analytical and Bioanalytical Chemistry, 403, 2891-2908, 2012)補充性的結果。泡沫(海綿)片直接以透過式模塊載樣輸送至 DART-高分辨質譜儀進行直接分析。為了更確切地鑒定農藥，我們建立了質子化母離子 [M+H]+ 的質量和同位素比例數據庫。該 HRAM(高分辨高質量精度)質譜配備四極桿質量過濾器，擁有“數據敲定(data-dependent)“的碰撞活化裂解能力。該能力 和“所有離子all -ion”裂解(所有的離子進入碰撞室后同時裂解)的質譜法有所不同。利用 DART 用氦氣的溫度梯度及質譜儀的多種碰撞活化能量，可以檢測并裂解164種不同種類、不同大小和極性的化學農藥。前體母離子和碎片離子的質量信息對于識別進口農產品表面化學污染物至關重要。此外，數據庫中的母離子的同位素信息則提供了另一個衡量標準來進一步加以識別。碎片數據的收集通過 Q-Exactive 型號的質譜來完成，之后添加到早先采用 Exactive 型號的質譜儀收集建立的數據庫當中。后者Exactive為較低端的型號，在普通篩查實驗室更容易配置。商品篩查的范圍非常廣泛，既有果皮光滑的產品如蘋果，又有表面粗糙的品種如花菜。極少量或者幾乎不需要的樣品制備、和無需色譜分離的特性，使該技術將每個樣品的分析周期大大縮短到了只有15分鐘，其簡單、穩定和實用的特性非常適用于快速篩查的目的。

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　文件名稱：使用原位電離 DART-MS 高分辨質譜技術并對照質量片段庫來快速分析農產品中的農藥 Accurate Mass Fragment Library for Rapid Analysis of Pesticides on Produce Using Ambient Pressure Desorption Ionization with High-Resolution Mass Spectrometry

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