Southern Nevada Water Authority, P.O. Box 99954, Las Vegas, Nevada 89193, United States.
Anal Chem. 2014 Jan 7;86(1):774-82. doi: 10.1021/ac403274a. Epub 2013 Dec 23.
An evaluation of existing analytical methods used to measure contaminants of emerging concern (CECs) was performed through an interlaboratory comparison involving 25 research and commercial laboratories. In total, 52 methods were used in the single-blind study to determine method accuracy and comparability for 22 target compounds, including pharmaceuticals, personal care products, and steroid hormones, all at ng/L levels in surface and drinking water. Method biases ranged from <10% to well over 100% in both matrixes, suggesting that while some methods are accurate, others can be considerably inaccurate. In addition, the number and degree of outliers identified suggest a high degree of variability may be present between methods currently in use. Three compounds, ciprofloxacin, 4-nonylphenol (NP), and 4-tert-octylphenol (OP), were especially difficult to measure accurately. While most compounds had overall false positive rates of ≤5%, bisphenol A, caffeine, NP, OP, and triclosan had false positive rates >15%. In addition, some methods reported false positives for 17β-estradiol and 17α-ethynylestradiol in unspiked drinking water and deionized water, respectively, at levels higher than published predicted no-effect concentrations for these compounds in the environment. False negative rates were also generally <5%; however, rates were higher for the steroid hormones and some of the more challenging compounds, such as ciprofloxacin. The elevated false positive/negative rates of some analytes emphasize the susceptibility of many current methods to blank contamination, misinterpretation of background interferences, and/or inappropriate setting of detection/quantification levels for analysis at low ng/L levels. The results of both comparisons were collectively assessed to identify parameters that resulted in the best overall method performance. Liquid chromatography-tandem mass spectrometry coupled with the calibration technique of isotope dilution were able to accurately quantify most compounds with an average bias of <10% for both matrixes. These findings suggest that this method of analysis is suitable at environmentally relevant levels for most of the compounds studied. This work underscores the need for robust, standardized analytical methods for CECs to improve data quality, increase comparability between studies, and help reduce false positive and false negative rates.
对用于测量新兴关注污染物（CECs）的现有分析方法进行了评估，这是通过涉及 25 个研究和商业实验室的实验室间比较进行的。在这项单盲研究中，共使用了 52 种方法来确定 22 种目标化合物（包括药品、个人护理产品和类固醇激素）在地表水和饮用水中的ng/L 水平的方法准确性和可比性。在两种基质中，方法偏差范围从<10%到>100%，这表明虽然一些方法是准确的，但其他方法可能存在相当大的误差。此外，鉴定出的离群值的数量和程度表明，目前使用的方法之间可能存在高度的可变性。三种化合物，环丙沙星、4-壬基酚（NP）和 4-叔辛基酚（OP），特别难以准确测量。虽然大多数化合物的总假阳性率≤5%，但双酚 A、咖啡因、NP、OP 和三氯生的假阳性率>15%。此外，一些方法在未加标饮用水和去离子水中分别报告了 17β-雌二醇和 17α-乙炔基雌二醇的假阳性，其水平高于这些化合物在环境中的公布预测无效应浓度。假阴性率也普遍<5%；然而，类固醇激素和一些更具挑战性的化合物（如环丙沙星）的假阴性率更高。一些分析物的假阳性/假阴性率升高强调了许多当前方法容易受到空白污染、背景干扰的错误解释以及/或在低 ng/L 水平下分析时检测/定量水平设置不当的影响。综合评估这两个比较的结果，以确定导致总体方法性能最佳的参数。液相色谱-串联质谱法结合同位素稀释校准技术能够准确地定量大多数化合物，两种基质的平均偏差<10%。这些发现表明，这种分析方法在环境相关水平上适用于大多数研究化合物。这项工作强调了需要有稳健的、标准化的 CEC 分析方法，以提高数据质量，增加研究之间的可比性，并有助于降低假阳性和假阴性率。
