The US Environmental Protection Agency (USEPA) and several states are considering regulatory limits for hexavalent chromium (Cr(VI)) <100 ng/L, increasing the importance of obtaining accurate and reliable data. The present study presents the results of 2 studies investigating the effectiveness of chemical preservation on ng/L concentrations of Cr(VI) in groundwater. Chemically preserved and unpreserved aliquots of a groundwater sample were spiked with a known amount of Cr(VI), and then analyzed in tandem with sets of preserved and unpreserved performance test samples over 28 d. The studies showed that although Cr(VI) appears to be relatively stable over 28 d, it may be sensitive to minor matrix changes after collection. The studies also demonstrated significant challenges to measuring Cr(VI) below 100 ng/L, because the results can be subject to positive bias or contamination that may not be readily apparent. We conclude that Cr(VI) measurements using a USEPA published method below 100 ng/L may be categorized as semiquantitative at best. Environ Toxicol Chem 2020;39:1526–1533. © 2020 SETAC

中文翻译：

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与生成地下水中六价铬的可靠每公升纳米级测量相关的挑战。

美国环境保护局（USEPA）和几个州正在考虑对<100 ng / L的六价铬（Cr（VI））进行管理的限制，这增加了获取准确可靠数据的重要性。本研究提出了两项​​研究结果，研究了化学防腐对地下水中Cr（VI）ng / L浓度的影响。用已知量的Cr（VI）加标地下水样品中化学保存和未保存的等分试样，然后在28 d内与多组保存和未保存的性能测试样品一起进行分析。研究表明，尽管Cr（VI）在28 d内相对稳定，但对收集后的微小基质变化可能敏感。研究还表明，测量低于100 ng / L的Cr（VI）面临重大挑战，因为结果可能会出现正偏差或可能不容易看出的污染。我们得出的结论是，使用USEPA发布的方法（低于100 ng / L）进行的Cr（VI）测量最多可归为半定量。2020年《环境毒理学》； 39：1526-1533。©2020 SETAC