Detection of PFAS via surface-enhanced Raman scattering: Challenges and future perspectives

The upsurge in the alarm about the hazardous effects of one of the important emerging contaminants, Per- and polyfluoroalkyl substances (PFASs) are increasing in recent days. Due to the widespread use of PFASs in various fields, it has a high tendency to be accumulated in the environment and living entities. Due to the persistent and carcinogenic nature of PFASs, it is necessary to detect and remove them from the environment. Chromatographic techniques combined with mass spectrometry are the current conventional methods for PFASs detection. Some more methods like liquid chromatography, solid-phase extraction, solid-phase mass extraction, tandem mass spectrometry, optical, electrochemical, fluorescence-based sensors, biosensors etc. are also implemented to detect PFASs. Even though these methods could detect perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), the detection limits attained through these methods are unsatisfactory, and the detection of other PFASs has not been prioritized. Surface-enhanced Raman scattering (SERS) technique can be a great solution for the sensing of PFASs as it is highly sensitive, specific, and having a lot of potential in water research for the detection of contaminants. Due to the challenges associated with detecting PFASs using surface-enhanced Raman spectroscopy (SERS), there is a limited amount of literature available on the detection of PFASs because of the difficulty of detection under SERS. The reason behind this is the strong fluorescence nature of PFASs, and it is widely recognized that distinguishing fluorescence emission from Raman scattering is challenging due to their similar origins. In this perspective, causes for fluorescence in Raman scattering and the different ways to diminish the fluorescence are detailed in the later section. The article discusses the limitations of current PFASs sensors, advantages and limitations of fluorescence-based detection of PFASs in Raman scattering. The challenges related to the PFASs detection and possible solutions to resolve the issues have been focused. Further, an insightful discussion towards future research directions in this field has been provided.