In vitro bioassays are increasingly applied for water quality monitoring, with assays indicative of adaptive stress responses commonly included in test batteries. The NF-κB assay is responsive to surface water and wastewater extracts, but the causative compounds are unknown and micropollutants typically found in water do not activate the NF-κB assay. The current study aimed to investigate if co-extracted organic matter and/or endotoxins could cause the NF-κB response in surface water extracts. The effect of model bacterial lipopolysaccharides (LPS) and dissolved organic carbon (DOC) was evaluated in the NF-κB assay both before and after solid-phase extraction (SPE), with 7% effect recovery for LPS and between 7 and 52% effect recovery for DOC observed. The NF-κB response, endotoxin activity, micropollutant concentration and total organic carbon concentration was measured in four surface water extracts. All water extracts showed a response in the NF-κB assay, but the detected micropollutants could not explain the effect. Comparison of predicted bioanalytical equivalent concentrations based on micropollutant, DOC and endotoxin concentrations in surface water with experimental bioanalytical equivalent concentrations suggest that co-extracted endotoxins are the most important drivers of the observed effect, with DOC only having a minor contribution. While in vitro bioassays typically detect mixtures of organic micropollutants, the current study shows that the NF-κB assay can integrate the effects of co-extracted endotoxins. Given that endotoxins can pose a risk for human health, the NF-κB assay is a valuable inclusion in bioanalytical test batteries used for water quality monitoring.

体外生物测定法越来越多地用于水质监测，其测定指示通常包含在测试电池中的适应性应激反应。NF-κB测定法对地表水和废水提取物有反应，但致病性化合物未知，水中常见的微量污染物不会激活NF-κB测定法。当前的研究旨在调查共提取的有机物和/或内毒素是否会引起地表水提取物中的NF-κB反应。在固相萃取（SPE）之前和之后，在NF-κB分析中评估了模型细菌脂多糖（LPS）和溶解的有机碳（DOC）的效果，LPS的回收率为7％，且回收率为7％至52％观察到DOC恢复。NF-κB反应，内毒素活性，测定了四种地表水提取物中的微污染物浓度和总有机碳浓度。所有水提取物在NF-κB分析中均显示出响应，但检测到的微量污染物不能解释其作用。基于地表水中微污染物，DOC和内毒素浓度的预测生物分析当量浓度与实验生物分析当量浓度的比较表明，共提取内毒素是观察到的效果的最重要驱动因素，而DOC的贡献很小。尽管 地表水中的DOC和内毒素浓度以及实验生物分析当量浓度表明，共提取内毒素是观察到的效果的最重要驱动因素，而DOC的贡献很小。尽管 地表水中的DOC和内毒素浓度以及实验生物分析当量浓度表明，共提取内毒素是观察到的效果的最重要驱动因素，而DOC的贡献很小。尽管体外生物测定法通常检测有机微量污染物的混合物，当前研究表明，NF-κB测定法可以整合共提取内毒素的作用。考虑到内毒素可能对人体健康构成威胁，NF-κB测定法是用于水质监测的生物分析测试电池中的重要组成部分。