Agilent 7000E 三重四极杆气质联用系统

前言 高分辨气相色谱质谱 (GC/MS) 系统的重要应用包括非靶向筛查方法以及未知化合物鉴定。对于许多类别化合物，低能量电子电离 (EI) 相比标准 (70 eV) EI 显著提高了分子离子的相对丰度，可以提高选择性和化合物鉴定能力，避免了由于更换离子源或进一步调谐而导致的停机时间。但是，其他离子源仍可以作为补充技术（即化学电离）与高分辨 GC/MS 联用，主要用于环境分析中重要的选定化合物分析。本研究将比较在 Agilent 7250 GC/Q-TOF 上采集的低能量 EI 和化学电离 (CI) 数据。

Abstract This application note illustrates a sensitive method used to analyze semivolatile organic compounds (SVOCs) on an Agilent 7000E triple quadrupole GC/MS system (GC/TQ). The use of GC/TQ instrumentation for analysis of SVOCs offers significant advantages. High selectivity afforded by multiple reaction monitoring (MRM) mode results in faster batch review and increased confidence due to the elimination of matrix interferences. These interferences are often present when using selective ion monitoring (SIM) or scan acquisition modes. Increased sensitivity can facilitate smaller extraction volumes that improve sustainability, reduce waste, and decrease costs associated with sample preparation, solvent usage, and waste disposal. A primary objective of this work was to demonstrate the ability of a GC/TQ to detect SVOCs at low levels to meet these laboratory needs while maintaining an excellent dynamic range.

Using the Agilent HydroInert source in a challenging soil matrix

本文介绍了一种使用 Agilent 7000D 三重四极杆气质联用系统 (GC-MS/MS) 分析化妆品中挥发性亚硝胺类化合物的方法。

前言 全球结核病 (TB) 的发病率非常高，据估计仅 2014 一年中就有 960 万新增 TB病例，并有 150 万名患者死于 TB [1]。采用代谢组学技术可以确认 TB 生物标记物，使我们对该疾病的认识取得很大进展。本研究中利用结核分枝杆菌(Mtb) 感染的小鼠模型来确定未感染和已感染 TB 的肺组织的代谢情况。 为了确认感染后产生的新病理生理途径和 TB 生物标记物，使用未感染和已感染（感染第 9 周）的肺组织进行非靶向代谢组学研究。在初步化合物标注之后，使用低能量 EI 数据确认分子离子，并分别鉴定初步分析出的化合物 与未知物的分子式。

本文介绍了一种用于分析甜菜中 267 种农药的简便、高通量方法。该方法将 QuEChERS 样品前处理方法与 Agilent 7000 系列三重四极杆气质联用系统相结合，并通过基质匹配标样校准进行定量，以降低基质干扰引起的定量偏差。结果表明，该方法在 2–200 μg/kg 的基质加标浓度范围内具有良好的线性关系。绝大部分目标农药化合物的定量限 (LOQ) 低至2 μg/kg，灵敏度高。加标回收率测试表明，在 2、5、10、100 和 200 μg/kg 的加标浓度下，大部分农药化合物的回收率在 80%–120% 的范围内 (n = 5) ，且相对标准偏差 (RSD)低于 10%。该方法适用于对甜菜中的多种农药残留进行常规分析。

Abstract This application note describes the use of the novel simultaneous dynamic multiple reaction monitoring (dMRM) and scan (dMRM/scan) data acquisition mode for triple quadrupole gas chromatography mass spectrometry (GC/TQ) analysis of pesticides in challenging food matrices. The simultaneous dMRM/scan capability enables identification of the unknown compounds and retrospective analysis, while maintaining sensitivity and dynamic range of the method comparable to a conventional dMRM analysis. Additionally, scan data enables more confidence in compound identification by library spectrum matching. Finally, the full scan data allow the analyst to evaluate the sample matrix to ensure the most efficient performance of the GC/TQ system. This work demonstrates the application of dMRM/scan to the analysis of extracts, using Agilent QuEChERS sample preparation, of spinach, walnut, and cayenne pepper spiked with over 200 pesticides. The calibration results and method sensitivity for 203 evaluated compounds were comparable to results observed with conventional dMRM data acquisition mode with the Agilent 8890/7000E GC/TQ and the Agilent 8890/7010C GC/TQ. The unknown identification workflow based on the spectral library matching using a retention time locked library was carried out with Agilent MassHunter Unknowns Analysis. Many of the compounds with the established maximum residue limits (MRLs) were identified with full scan data at concentrations below their MRLs even in the challenging cayenne pepper extract

Abstract This application note describes two approaches for achieving robust, multiresidue pesticide analysis in 10 minutes by GC/MS/MS, while maintaining sufficient chromatographic resolution for the analysis of over 200 pesticides in spinach; a challenging high chlorophyll, fresh matrix. First, the conventional 15 × 15 m (0.25 mm × 0.25 μm) midcolumn backflush configuration was used with an accelerated oven ramp, yielding an analysis time of 10 minutes. Second, a minibore 10 × 10 m (0.18 mm × 0.18 μm) midcolumn backflush configuration was used, enabling a fast 10-minute analysis time. The latter method was precisely scaled using the Agilent GC method translation technique. It was shown that midcolumn backflushing enabled method robustness and extended maintenance-free operation of the system by minimizing column trimming and source cleaning. Results demonstrate that the Agilent 7000E and 7010C triple quadrupole GC/MS systems delivered excellent linearity over a concentration range of 0.1 to 1,000 parts per billion (ppb). Method robustness was shown with 700 consecutive injections of a spinach extract, spiked with pesticides at 20 ppb, that spanned over 175 hours of continuous running of the GC/TQ.

Abstract This application note describes the key strategies for pesticide analysis with gas chromatography/triple quadrupole mass spectrometry (GC/TQ) using hydrogen as the carrier gas while maintaining sensitivity to meet maximum residue limits (MRLs). The key aspects addressed in this work include the recommended column configuration, the optimized injection conditions, and the appropriate choice of the mass spectrometer (MS) electron ionization (EI) source hardware developed for use with hydrogen carrier gas. The 20 m × 20 m (0.18 mm × 0.18 μm) Agilent HP-5ms UI midcolumn backflush configuration allowed for maintaining the same retention times as with helium, leading to time savings associated with method translation. The resulting chromatographic resolution achieved under the optimal conditions with hydrogen surpassed that with helium. The optimized injection conditions included solvent vent mode, a 2 mm dimpled liner, and the use of analyte protectants. The analyte response with hydrogen was enhanced on average 10-fold when using the optimized conditions compared to using hydrogen carrier gas with the injection conditions, commonly used with helium. Both the Agilent HydroInert and the Agilent High Efficiency Source (HES) resulted in nearly identical spectra bserved with hydrogen and helium, which allowed using the same multiple reaction monitoring (MRM) transitions and collision energies as with helium. The ability to use the same MRMs, collision energies, and retention times greatly simplified the transition from helium to hydrogen.