Using prepared mixtures of ToxCast chemicals to evaluate non-targeted analysis (NTA) method performance
Using prepared mixtures of ToxCast chemicals to evaluate non-targeted analysis (NTA) method performance
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DOI：
10.1007/s00216-018-1526-4
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发表时间：
2019-02-01
影响因子：
4.3
通讯作者：
Ulrich, Elin M.
中科院分区：
文献类型：
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作者：
Sobus, Jon R.;Grossman, Jarod N.;Ulrich, Elin M.
非目标分析(NTA)方法越来越多地被用于发现新出现的令人担忧的污染物(CECs)，但这些方法能够在多大程度上支持暴露和健康研究仍有待确定。环保局的非靶向分析合作试验(ENTACT)于2016年启动，以满足这一需求。作为ENTACT的一部分，EPA ToxCast库中的1269种独特物质被组合在一起，制成了10种合成混合物，每个混合物含有95到365种物质。作为试验的参与者，我们首先对每一种混合物进行了盲法NTA，使用了高效液相色谱(LC)和高分辨率质谱仪(HRMS)相结合的方法。然后，我们进行了一次非盲目评估，以确定我们的NTA方法的局限性。总体而言，使用选定的方法可以观察到至少60%的添加物质。剔除添加的异构体，盲法和非盲法分析的真阳性率分别达到最高46%和65%。对于添加到不止一种混合物中并至少观察一次的物质，观察到总的重现率为75%。当比较我们两种不同的反相色谱方法得到的结果的子集时，在物质鉴定方面观察到相当大的不一致。我们的结论是，一种单一的NTA方法，即使经过优化，也很可能只能表征ToxCast物质的子集(进而，也可以表征其他CEC)。实验室生成NTA数据以支持暴露和健康研究时，应要求严格的质量控制和自我评估做法。准确和透明地传达业绩结果将使对国家技术援助数据的有意义的解释和合理的使用成为可能。
Non-targeted analysis (NTA) methods are increasingly used to discover contaminants of emerging concern (CECs), but the extent to which these methods can support exposure and health studies remains to be determined. EPA's Non-Targeted Analysis Collaborative Trial (ENTACT) was launched in 2016 to address this need. As part of ENTACT, 1269 unique substances from EPA's ToxCast library were combined to make ten synthetic mixtures, with each mixture containing between 95 and 365 substances. As a participant in the trial, we first performed blinded NTA on each mixture using liquid chromatography (LC) coupled with high-resolution mass spectrometry (HRMS). We then performed an unblinded evaluation to identify limitations of our NTA method. Overall, at least 60% of spiked substances could be observed using selected methods. Discounting spiked isomers, true positive rates from the blinded and unblinded analyses reached a maximum of 46% and 65%, respectively. An overall reproducibility rate of 75% was observed for substances spiked into more than one mixture and observed at least once. Considerable discordance in substance identification was observed when comparing a subset of our results derived from two separate reversed-phase chromatography methods. We conclude that a single NTA method, even when optimized, can likely characterize only a subset of ToxCast substances (and, by extension, other CECs). Rigorous quality control and self-evaluation practices should be required of labs generating NTA data to support exposure and health studies. Accurate and transparent communication of performance results will best enable meaningful interpretations and defensible use of NTA data.