Moschet Christoph, Lew Bonny M, Hasenbein Simone, Anumol Tarun, Young Thomas M
Department of Civil and Environmental Engineering, University of California , One Shields Avenue, Davis, California 95616, United States.
Agilent Technologies Inc., 2850 Centerville Road, Wilmington, Delaware 19808, United States.
Environ Sci Technol. 2017 Feb 7;51(3):1553-1561. doi: 10.1021/acs.est.6b05352. Epub 2017 Jan 18.
Efficient strategies are required to implement comprehensive suspect screening methods using high-resolution mass spectrometry within environmental monitoring campaigns. In this study, both liquid and gas chromatography time-of-flight mass spectrometry (LC-QTOF-MS and GC-QTOF-MS) were used to screen for >5000 target and suspect compounds in the Sacramento-San Joaquin River Delta in Northern California. LC-QTOF-MS data were acquired in All-Ions fragmentation mode in both positive and negative electrospray ionization (ESI). LC suspects were identified using two accurate mass LC-QTOF-MS/MS libraries containing pesticides, pharmaceuticals, and other environmental contaminants and a custom exact mass database with predicted transformation products (TPs). The additional fragment information from the All-Ions acquisition improved the confirmation of the compound identity, with a low false positive rate (9%). Overall, 25 targets, 73 suspects, and 5 TPs were detected. GC-QTOF-MS extracts were run in negative chemical ionization (NCI) for 21 targets (mainly pyrethroids) at sub-ng/L levels. For suspect screening, extracts were rerun in electron ionization (EI) mode with a retention time locked method using a GC-QTOF-MS pesticide library (containing exact mass fragments and retention times). Sixteen targets and 42 suspects were detected, of which 12 and 17, respectively, were not identified by LC-ESI-QTOF-MS. The results highlight the importance of analyzing water samples using multiple separation techniques and in multiple ionization modes to obtain a comprehensive chemical contaminant profile. The investigated river delta experiences significant pesticide inputs, leading to environmentally critical concentrations during rain events.
在环境监测活动中，需要高效的策略来实施使用高分辨率质谱的全面可疑物筛查方法。在本研究中，液相色谱-飞行时间质谱（LC-QTOF-MS）和气相色谱-飞行时间质谱（GC-QTOF-MS）均用于筛查加利福尼亚州北部萨克拉门托-圣华金河三角洲的5000多种目标化合物和可疑化合物。LC-QTOF-MS数据在正、负电喷雾电离（ESI）的全离子碎裂模式下采集。使用两个包含农药、药品和其他环境污染物的精确质量LC-QTOF-MS/MS库以及一个带有预测转化产物（TPs）的定制精确质量数据库来鉴定LC可疑物。全离子采集提供的额外碎片信息提高了化合物身份确认的准确性，假阳性率较低（9%）。总体而言，检测到25种目标化合物、73种可疑物和5种TPs。GC-QTOF-MS提取物在负化学电离（NCI）模式下运行，检测21种目标化合物（主要是拟除虫菊酯类），浓度低于纳克/升水平。对于可疑物筛查，提取物在电子电离（EI）模式下重新运行，采用保留时间锁定方法，使用GC-QTOF-MS农药库（包含精确质量碎片和保留时间）。检测到16种目标化合物和42种可疑物，其中分别有12种和17种未被LC-ESI-QTOF-MS鉴定。结果突出了使用多种分离技术和多种电离模式分析水样以获得全面化学污染物概况的重要性。所研究的河三角洲农药输入量很大，导致降雨事件期间出现对环境至关重要的浓度。
