Dissolved organic matter (DOM) exists ubiquitously in the aquatic environment with varying chemical compositions and a wide molecular weight (MW) distribution, which, as a result, exhibits differing impacts on the behavior and fate of contaminants. The current methods for the MW characterization of DOM usually possess some weaknesses and therefore, some novel techniques are needed. In this study, the feasibility and sensitivity of flow field‐flow fractionation (FlFFF) system were studied for the MW characterization of DOMs from various origins. The systematic evaluation of FlFFF indicated that a mobile phase consisting of 10 mM NaCl and 5 mM H₃BO₃ and with a pH of 8 was optimal, and the fractionation program with a cross‐flow rate of 2 mL/min and a focusing time of 2 min resulted in the most efficient MW fractionation. Compared to natural waters, the standard DOM materials possessed a high proportion of humic‐like substances and narrow MW distribution. The quantification analysis showed that chromophoric organic ligands were mainly distributed in the high (i.e., 100 kDa–0.45 μm) and low (i.e., 0.3–1 kDa) MW fractions for natural waters, but in the medium (i.e., 1–100 kDa) and low MW fractions for the standard DOM materials. However, the fluorescent humic‐like substances were predominantly distributed within the medium and low MW fractions, irrespective of DOM types. This study showed the feasibility and sensibility of FlFFF in fractionating DOM samples, and can be used to quantify the different MW distribution of chromophoric and fluorescent components in standard and natural DOM.

中文翻译：

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利用流场-流分馏法表征和修饰溶解有机物中的分子量分布

溶解的有机物（DOM）在水生环境中普遍存在，具有变化的化学组成和较宽的分子量（MW）分布，因此对污染物的行为和归宿表现出不同的影响。DOM的MW表征的当前方法通常具有一些缺点，因此，需要一些新颖的技术。在这项研究中，研究了流场-流分馏（FlFFF）系统对来自不同来源的DOM的MW表征的可行性和敏感性。FlFFF的系统评估表明，流动相由10 mM NaCl和5 mM H ₃ BO _3组成最佳pH值为8，错流程序的错流率为2 mL / min，聚焦时间为2 min导致了最有效的MW分馏。与天然水相比，标准DOM材料具有高比例的腐殖质物质和窄的MW分布。定量分析表明，发色有机配体主要分布在天然水的高（即100 kDa–0.45μm）和低（即0.3–1 kDa）MW馏分中，但分布在中等（即1–100 kDa）中）和标准DOM材料的低MW分数。但是，荧光腐殖质样物质主要分布在中等和低分子量级分内，与DOM类型无关。这项研究表明FlFFF在分离DOM样品中的可行性和敏感性，