Reducing Interferences from Organic Matter during Optical Environmental Detection using SERS-Silent Region Nanosensors: A Case of Nitrite Detection

Optical detection techniques are frequently used in environmental monitoring due to their high sensitivity and stability; however, to decrease the optical interferences from environmental matrix remains challenging. Herein, to decrease the optical interferences from dissolved organic matter (DOM), a surface-enhanced Raman scattering (SERS)-silent region (1800–2800 cm–1) sensor has been studied for the detection of NO2– (a model pollutant) in the presence of DOM. 4-Ethynylaniline (4-EA) was selected as the sensing molecule. The signal band (2205 cm–1) and the internal standard band of 4-EA (1985 cm–1) in the SERS-silent region are used for the quantitative analysis of NO2–. Since the SERS-silent region can well avoid the overlapping with the DOM signal, the dual-silent band ratio I2205/I1985 exhibits outstanding anti-interference ability toward different common organic matter. Compared with the traditional UV–vis detection, this method maintains a higher sensitivity (with a detection limit of 10–7 M) and a better accuracy (detection recovery ranges from 89.9 to 109.7%) for NO2– detection in real samples. Furthermore, this SERS dual-silent region sensor has been successfully employed in an environmental survey of a local river. These findings imply that the SERS-silent nanosensor provides a way to develop accurate optical detection techniques for environmental monitoring.