Vu-Duc Nam, Nguyen-Quang Trung, Le-Minh Thuy, Nguyen-Thi Xuyen, Tran Tri Manh, Vu Hai Anh, Nguyen Lan-Anh, Doan-Duy Tien, Van Hoi Bui, Vu Cam-Tu, Le-Van Dung, Phung-Thi Lan-Anh, Vu-Thi Hong-An, Chu Dinh Binh
Center for Research and Technology Transfer, Vietnam Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Hanoi 100000, Vietnam.
Faculty of Chemistry, VNU University of Science, Vietnam National University-Hanoi, 19 Le Thanh Tong, Hanoi 100000, Vietnam.
J Anal Methods Chem. 2019 May 8;2019:3489634. doi: 10.1155/2019/3489634. eCollection 2019.
An ultrahigh-performance liquid chromatography in combination with high-resolution mass spectrometry Thermo Q-Extractive Focus Orbitrap MS has been introduced for analysis of multiclass pesticides in vegetable samples collected in Hanoi, Vietnam. Multiclass pesticides were separated on the Thermo Hypersil Gold PFP column utilizing a gradient of the mobile phase consisting of 5 mM ammonium formate, 0.1% formic acid in deionized water, and methanol. The target analytes were detected in the full-scan mode on Thermo Scientific Q-Exactive Focus Orbitrap MS for quantitation at the optimum operating conditions. These conditions included, but not limit to, the resolution of 70000 at the full width at half maximum in both positive and negative mode, mass range from 80 to 1000 , and optimized parameters for the heated electrospray ionization source. The identification of the analytes in real samples was based on retention times, mass to charge ratios, mass accuracies, and MS/MS spectra at the confirmation mode with the inclusion list of target analytes. The mass accuracies of target analytes were from -4.14 ppm (dinotefuran) to 1.42 ppm (cinosulfuron) in the neat solvent and from -3.91 ppm (spinosad D) to 1.29 ppm (cinosulfuron) in the matrix-matched solution. Target analytes in the vegetable-based matrix were extracted by the QuEChERS method. Some critical parameters of the analytical method such as linearity, repeatability, limit of detection, and limit of quantitation have been evaluated and implemented. Excellent LOD and LOQ of the developed method were achieved at the range of 0.04-0.85 and 0.13-2.9 g·kg, respectively. Intraday and interday repeatability of the analytical signal (peak area, =6) of the developed method were below 3% and 10%, correspondingly. The matrix effect, extraction recovery, and overall recovery were fully investigated by spiking experiments. Experimental results demonstrated that the ionization suppression or enhancement was the main contribution on the overall recoveries of target analytes. Finally, the in-house validated method was applied to pesticides screening in vegetables samples in local villages in Hanoi, Vietnam. The concentrations of all target analytes were below limit of quantitation and lower than US-FDA or EU maximum residue levels.
一种结合了超高效液相色谱和高分辨率质谱（Thermo Q-Extractive Focus Orbitrap MS）的方法已被用于分析在越南河内采集的蔬菜样本中的多类农药。多类农药在Thermo Hypersil Gold PFP柱上进行分离，流动相采用由5 mM甲酸铵、0.1%甲酸的去离子水和甲醇组成的梯度洗脱。在Thermo Scientific Q-Exactive Focus Orbitrap MS上以全扫描模式检测目标分析物，以便在最佳操作条件下进行定量分析。这些条件包括但不限于在正、负模式下半峰宽处分辨率为70000、质量范围为80至1000 以及加热电喷雾电离源的优化参数。实际样品中分析物的鉴定基于保留时间、质荷比、质量精度以及在确证模式下目标分析物包含列表的MS/MS谱图。目标分析物在纯溶剂中的质量精度为-4.14 ppm（噻虫嗪）至1.42 ppm（氯嘧磺隆），在基质匹配溶液中的质量精度为-3.91 ppm（多杀菌素D）至1.29 ppm（氯嘧磺隆）。基于蔬菜的基质中的目标分析物采用QuEChERS方法进行提取。已对该分析方法的一些关键参数如线性、重复性、检测限和定量限进行了评估和测定。所开发方法的出色检测限和定量限分别在0.04 - 0.85和0.13 - 2.9 μg·kg范围内实现。所开发方法的分析信号（峰面积，n = 6）的日内和日间重复性分别低于3%和10%。通过加标实验对基质效应、提取回收率和总回收率进行了全面研究。实验结果表明，电离抑制或增强是目标分析物总回收率的主要影响因素。最后，该内部验证方法被应用于越南河内当地村庄蔬菜样本中的农药筛查。所有目标分析物的浓度均低于定量限，且低于美国食品药品监督管理局（US-FDA）或欧盟的最大残留限量。
