Analytical Research Group, Chair of Urban Water Systems Engineering, Technical University of Munich , Am Coulombwall 3, 85748 Garching, Germany.
Anal Chem. 2017 Aug 1;89(15):7907-7914. doi: 10.1021/acs.analchem.7b00859. Epub 2017 Jul 12.
Trace organic compounds are important in environmental analysis because they impact water quality and introduce potential (eco)toxicological effects. Current analytical methods mostly rely on gas chromatography (GC) or reversed-phase liquid chromatography (RPLC) coupled with (tandem) mass spectrometry. However, neither method can easily separate very polar molecules. This study presents two chromatographic separation strategies, a serial RPLC-hydrophilic interaction liquid chromatography (RPLC-HILIC) coupling and an analytical scale supercritical fluid chromatography (SFC) system, and validates their separation effectiveness as polarity-extended chromatographic methods for 274 environmentally relevant compounds. Compounds tested were grouped into three polarity classes, "very polar" {log D (pH 7) below -2.5}, "polar" {log D (pH 7) -2.5 to +2}, and "non-polar" {log D (pH 7) higher than +2}). Nearly all compounds could be retained in both systems with relative standard deviations of retention times (RT; n = 6) typically between 2 and 5%. Both techniques have considerable benefits when combined with accurate mass spectrometric detection. Molecules RT and accurate mass were recorded in a database for each set up. This information was used for compound screening measurements like "hidden-target screening" in complex environmental matrices (such as wastewater treatment plant effluents). Results of both techniques are complementary and useful for all types of molecules polarity. In this study, more than 80% of the compounds found in wastewater treatment plant effluent samples possessed a negative log D (pH 7) value. This result highlights the basic necessity to include "very polar" compounds in water monitoring techniques and protocols.
痕量有机化合物在环境分析中很重要，因为它们会影响水质并引入潜在的（生态）毒理学效应。目前的分析方法主要依赖于气相色谱（GC）或反相液相色谱（RPLC）与（串联）质谱联用。然而，这两种方法都不容易分离非常极性的分子。本研究提出了两种色谱分离策略，即串联 RPLC-亲水相互作用液相色谱（RPLC-HILIC）偶联和分析规模超临界流体色谱（SFC）系统，并验证了它们作为扩展极性的色谱方法对 274 种环境相关化合物的分离效果。所测试的化合物被分为三类极性，“非常极性”{log D（pH 7）低于-2.5}，“极性”{log D（pH 7）-2.5 至+2}和“非极性”{log D（pH 7）高于+2}）。几乎所有化合物都可以在这两种系统中保留，保留时间（RT）的相对标准偏差（n=6）通常在 2%至 5%之间。这两种技术与准确的质谱检测相结合时都具有很大的优势。为每个设置记录了分子的 RT 和准确质量，并将其记录在数据库中。该信息可用于复杂环境基质（如污水处理厂废水）中的化合物筛选测量，如“隐藏目标筛选”。两种技术的结果都是互补的，适用于所有类型的分子极性。在本研究中，污水处理厂废水中发现的化合物中有 80%以上具有负的 log D（pH 7）值。这一结果突出了在水质监测技术和方案中包含“非常极性”化合物的基本必要性。
