基于氮掺杂荧光碳点“on-off-on”模式的杀草强检测方法

Amitrole detection based on carbon dots fluorescence of“on-off-on”mode

以柠檬酸为碳源、尿素为氮源,采用一步水热法合成了氮掺杂的蓝色荧光碳点(N-CDs),并利用高分辨率透射电子显微镜(HR-TEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)、紫外光谱和红外光谱对其形貌和结构进行表征。结果显示,N-CDs呈分散良好的球状颗粒,平均粒径为2.90±0.30 nm。Fe 3+能与N-CDs表面的含氮基团络合致其荧光猝灭,而农药杀草强(AMT)与Fe 3+具有更强的亲和力,当N-CDs/Fe 3+共存体系中存在AMT时,Fe 3+被AMT竞争下来,可以使N-CDs的荧光得以恢复,基于该原理建立了氮掺杂碳点荧光“on-off-on”模式检测杀草强的方法。经测定,所建立方法的线性范围为0.40~40.00μg/mL,相关系数为0.9996,检出限为0.18μg/mL;其他离子和农药对其均无明显影响,方法特异性良好。将该方法应用于实际样品中杀草强的检测,回收率为100.01%~115.43%,效果良好,具有潜在的应用前景。

Nitrogen-doped blue fluorescent carbon dots(N-CDs)were synthesized by one-step hydrothermal method using citric acid as the carbon source and urea as the nitrogen source.The morphology and structure of N-CDs were characterized by high resolution transmission electron microscopy(HR-TEM),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),ultraviolet spectroscopy and infrared spectroscopy.The results showed that the N-CDs were well-dispersed spherical particles with an average particle size of 2.90±0.30 nm.Fe 3+could combine with the nitrogen-containing groups on the surface of N-CDs,leading to their fluorescence burst,while pesticide amitrole(AMT)has stronger affinity with Fe 3+.When AMT is present in the N-CDs/Fe 3+coexistence system,Fe 3+could be desorbed through AMT competition and the fluorescence of N-CDs can be restored.Based on the above principle,an“on-off-on”fluorescence detection method was developed to detect amitrole in nitrogen-doped carbon dots.The linear range of the method was 0.40~40.00μg/mL,the correlation coefficient was 0.9996 and the detection limit was 0.18μg/mL.Other ions and pesticides showed little interference on the method,thus demonstrating good specificity.The method was also applied for AMT detection in real samples with the recoveries of 100.01%~115.43%,which is satisfactory and has good application prospect.