Eranikkal Numy, Riyamol K R, Shafaf Hajera, Nawshad Mohammad, Maurya Muni Raj, Hasan Anwarul, Das Probir, Sadasivuni Kishor Kumar
Center for Advanced Materials, Qatar University, P.O. Box 2713, Doha, Qatar.
Department of Mechanical and Industrial Engineering, Qatar University, P.O. Box 2713, Doha, Qatar.
J Fluoresc. 2025 Jun 24. doi: 10.1007/s10895-025-04399-4.
This study presents a rapid, green, and highly sensitive fluorescence-based method for detecting urea in soil using nitrogen-doped carbon dots (CDs) synthesized via a microwave-assisted process. Citric acid and urea were used as carbon and nitrogen precursors, respectively, with optimal synthesis achieved at a 1:1 weight ratio and 9 min of microwave irradiation. The structural properties of nitrogen-doped carbon dots (CDs) were studied using X-ray Diffraction (XRD). Transmission Electron Microscopy (TEM) technique was used to observe the shape and size of the CDs, providing insight into their morphology. To understand the chemical composition, bonding states, and surface functionalities, X-ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FTIR) analyses were carried out. The performance of the nitrogen-doped-CDs in detecting urea, including their sensitivity and selectivity, was evaluated using fluorescence spectroscopy. The resulting CDs exhibited enhanced fluorescence properties and a limit of detection (LOD) as low as 143 mg/gm. The method demonstrated high selectivity toward urea even in the presence of interfering metal ions, and its effectiveness was validated in soil samples under varying pH conditions. This approach provides a cost-effective, scalable, and environmentally friendly solution for real-time monitoring of soil nutrients, supporting sustainable agricultural practices through improved nitrogen management.
本研究提出了一种快速、绿色且高灵敏度的基于荧光的方法,用于使用通过微波辅助过程合成的氮掺杂碳点(CDs)检测土壤中的尿素。柠檬酸和尿素分别用作碳源和氮源前体,在1:1的重量比和9分钟的微波辐射下实现了最佳合成。使用X射线衍射(XRD)研究了氮掺杂碳点(CDs)的结构性质。透射电子显微镜(TEM)技术用于观察CDs的形状和尺寸,以深入了解其形态。为了了解化学成分、键合状态和表面官能团,进行了X射线光电子能谱(XPS)和傅里叶变换红外光谱(FTIR)分析。使用荧光光谱法评估了氮掺杂CDs在检测尿素方面的性能,包括其灵敏度和选择性。所得的CDs表现出增强的荧光特性,检测限(LOD)低至143 mg/gm。该方法即使在存在干扰金属离子的情况下对尿素也具有高选择性,并且其有效性在不同pH条件下的土壤样品中得到了验证。这种方法为实时监测土壤养分提供了一种经济高效、可扩展且环境友好的解决方案,通过改善氮管理支持可持续农业实践。
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