Hazardous 4‐nitrophenol (4‐NP) has created serious threats to humans and the environment; therefore, it is highly desirable to develop a facile and practical method for the monitoring of 4‐NP in environment and food. Here, a fluorescence method based on modified polyethyleneimine‐capped carbon dots (mPEI‐CDs) was developed for sensitive and selective determination of 4‐NP in water, fruit, and vegetable samples. First, highly fluorescent mPEI‐CDs (quantum yield about 40.3%) were easily synthesized via a one‐step hydrothermal method by using novel acetic anhydride modified polyethyleneimine (mPEI) and citric acid as precursors. Compared to the unmodified PEI‐CDs, the acetic anhydride mPEI‐CDs exhibited excellent fluorescent stability in a wider pH range of 4.0–9.0. Under pH 8.0, a selective determination of 4‐NP was achieved based on the inner filter effect (IFE) mechanism. After optimization, good linear relationships between fluorescence intensity function (F₀‐F)/F₀ and the concentration of 4‐NP were obtained in ranges of 0.5–10 and 10–100 μM, respectively, while efficiently avoiding the interferences from two other nitrophenol isomers, possible coexisting metal cations and anions in samples. Finally, the proposed approach was successfully applied for the determination of 4‐NP in water, honey, strawberry, and tomato samples.

中文翻译：

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修饰的亚胺亚胺封顶的碳点灵敏和选择性地测定水和食品中的4-硝基苯酚

危险的4-硝基苯酚（4-NP）对人类和环境造成了严重威胁；因此，迫切需要开发一种简便实用的方法来监测环境和食品中的4-NP。在这里，开发了一种基于修饰的聚乙烯亚胺基碳点（mPEI-CD）的荧光方法，用于灵敏和选择性地测定水，水果和蔬菜样品中的4-NP。首先，使用新型乙酸酐改性的聚乙烯亚胺（mPEI）和柠檬酸作为前体，通过一步水热法可以轻松合成高荧光mPEI-CD（量子产率约为40.3％）。与未修饰的PEI-CD相比，乙酸酐mPEI-CD在4.0-9.0的较宽pH范围内均具有出色的荧光稳定性。在pH 8.0下，基于内部过滤效应（IFE）机理，对4-NP进行了选择性测定。优化后，荧光强度函数之间的线性关系良好（F₀ -F）/ F ₀和4-NP的浓度分别在0.5–10和10–100μM的范围内获得，同时有效避免了其他两种硝基酚异构体的干扰，样品中可能同时存在金属阳离子和阴离子。最后，该方法成功地用于水，蜂蜜，草莓和番茄样品中4-NP的测定。