Microextraction based on microplastic followed by SERS for on-site detection of hydrophobic organic contaminants, an indicator of seawater pollution

Microplastics (MPs) have been proven to concentrate hydrophobic organic contaminants (HOCs) from seawater as the sorbent phase, and the concentration of HOCs in aqueous solutions could be estimated from MPs preloaded with HOCs by equilibrium partition coefficient. This study firstly proposed to in situ quantify fluoranthene (a representative HOCs) pre-concentrated on MPs using surface enhance raman scattering (SERS) in combination with mathematical models, as an efficient monitoring tool for fluoranthene pollution in the aquatic environment. AgNPs-coated quartz (AgNPs@SiO2) substrate was fabricated. The SERS substrate was tested using fluoranthene standard solution with the minimal detectable concentration of 1 ng/mL achieved. Applying SERS for the detection of fluoranthene sorbed on MPs, the detection limit of fluoranthene on MPs was 3.3 ng/g, where the concentration in the corresponding equilibrium seawater was 0.97 ng/mL. Since more than one fluoranthene peak was observed, the quantitative detection was investigated by interval partial least square model. Eight characteristic peak ranges were selected to develop the model for predicting fluoranthene concentration, with Rc and Rv of 0.90 and 0.82, respectively. The study provides a promising solution to monitor trace level of contaminations in aquatic environment, using MPs as the passive sampler.