Department of Industrial Engineering, University of Rome Tor Vergata, 00133 Rome, Italy.
Department of Chemical Sciences and Technology, University of Rome Tor Vergata, 00133 Rome, Italy.
Sensors (Basel). 2022 Mar 24;22(7):2487. doi: 10.3390/s22072487.
In this study, nitrogen and sulfur co-doped carbon dots (NS-CDs) were investigated for the detection of heavy metals in water through absorption-based colorimetric response. NS-CDs were synthesized by a simple one-pot hydrothermal method and characterized by TEM, STEM-coupled with energy dispersive X-ray analysis, NMR, and IR spectroscopy. Addition of Cu(II) ions to NS-CD aqueous solutions gave origin to a distinct absorption band at 660 nm which was attributed to the formation of cuprammonium complexes through coordination with amino functional groups of NS-CDs. Absorbance increased linearly with Cu(II) concentration in the range 1-100 µM and enabled a limit of detection of 200 nM. No response was observed with the other tested metals, including Fe(III) which, however, appreciably decreased sensitivity to copper. Increase of pH of the NS-CD solution up to 9.5 greatly reduced this interference effect and enhanced the response to Cu(II), thus confirming the different nature of the two interactions. In addition, a concurrent response to Co(II) appeared in a different spectral region, thus suggesting the possibility of dual-species multiple sensitivity. The present method neither requires any other reagents nor any previous assay treatment and thus can be a promising candidate for low-cost monitoring of copper onsite and by unskilled personnel.
在这项研究中，通过基于吸收的比色响应，研究了氮硫共掺杂碳点（NS-CDs）用于水中重金属的检测。NS-CDs 通过简单的一锅水热法合成，并通过 TEM、与能量色散 X 射线分析相结合的 STEM、NMR 和 IR 光谱进行了表征。向 NS-CD 水溶液中加入 Cu(II)离子会在 660nm 处产生一个明显的吸收带，这归因于通过与 NS-CDs 的氨基官能团配位形成铜氨配合物。吸光度随 Cu(II)浓度在 1-100µM 范围内呈线性增加，检测限为 200nM。其他测试金属没有响应，包括 Fe(III)，但它会显著降低对铜的灵敏度。将 NS-CD 溶液的 pH 增加到 9.5 会大大降低这种干扰效应，并增强对 Cu(II)的响应，从而证实了两种相互作用的不同性质。此外，在不同的光谱区域同时出现了对 Co(II)的响应，这表明了双物种多重灵敏度的可能性。本方法既不需要任何其他试剂，也不需要任何先前的分析处理，因此有望成为现场和非专业人员低成本监测铜的有前途的候选方法。
