Xenobiotic Contamination of Water by Plastics and Pesticides Revealed through Real-Time, Ultrasensitive, and Reliable Surface-Enhanced Raman Scattering

Abstract

Uncontrolled utilization and consequent ubiquitous percolation of carcinogenic and xenobiotic contaminants, such as plasticizers and pesticides, into the ecosystem have created an immediate demand for robust analytical detection techniques to identify their presence in water. Addressing this demand, we uncover the presence of xenobiotic contaminants such as bisphenol A (BPA), triclosan (TC), and dimethoate (DM) through a robust, ultrasensitive, and reliable surface-enhanced Raman scattering (SERS) platform. Thereby, conclusive real-time evidence of degradation of polyethylene terephthalate (PET) leading to the release of BPA in water is presented. Worryingly, the release of BPA occurs at ambient temperature (40 °C) and within realistic time scales (12 h) that are regularly encountered during the handling, transport, and storage of PET-based water containers. Complementary mass-spectrometric, surface-specific atomic force microscopy and surface-selective X-ray photoelectron spectroscopy confirm the nanoscale surface degradation of PET through a loss of C═O and C–O surface functionalities. Such ultrasensitive (ppm-level) spectroscopic detection is enabled by the bottom-up assemblies of metal nanoparticles (Soret colloids, SCs) acting as SERS platforms to provide high analytical enhancement factor (108) with high reliability (relative standard deviation, RSD < 5%). Effective and rapid detection (30 s) of several other potential xenobiotic contaminants such as triclosan (TC) and dimethoate (DM) over a wide range of concentrations (10–5–10–1 M) has also been demonstrated. Finally, nondestructive real-time spectroscopic “sniffing” of organophosphorous pesticides from the surface of fruits is achieved, illustrating the multiphasic versatility of this label-free, non-lithography-based SERS platform.