Integrated sampling and in situ SERS detection of diquat and paraquat using silver nanostars-modified PTFE substrates

A surface-enhanced Raman spectroscopy (SERS) strategy for integrated sampling and in situ detection of diquat (DQ) and paraquat (PQ) in air and water is presented. By leveraging the unique characteristics of the SERS fingerprint alongside the exceptional adsorption capacity of porous polytetrafluoroethylene (PTFE) membranes, we synthesized a composite substrate consisting of porous PTFE and silver nanostars (AgNSts). Utilizing the AgNSts@PTFE filter, DQ and PQ can be sampled with an air sampler and detected in situ using a portable Raman spectrometer effectively, without pre-processing steps. Strong correlations were found between SERS intensity and logarithmic analyte concentration, with R² values between 0.937 and 0.968. The detection limits for DQ and PQ were 0.74 ppb and 0.23 ppb, respectively, and are below the permissible concentrations. This study presents a novel, rapid method for detecting DQ and PQ in aerosols in non-laboratory settings, offering an alternative approach to conventional techniques.