Highly selective electrochemical impedance spectroscopy-based graphene electrode for rapid detection of microplastics

The widespread occurrence of microplastics (MPs) in aquatic ecosystems that caused environmental pollution has attracted worldwide attention. Herein, graphene electrode was initially derived from petroleum waste. Then the electrochemical responses of the electrode were evaluated using electrochemical impedance spectroscopy (EIS) toward polystyrene (PS) under various optimum conditions. For the quantitative measurement of PS concentration, principal component analysis (PCA) score images displayed that the data points offered the best discrimination of the classes, and singular value decomposition (SVD) showed that a good linearity was achieved between Z"u(1) and lgC_ps in the concentration range of 0.01-25 mg L^-1. Especially for PS with particle size of 1 μm, the highest correlation coefficient (R² = 0.9914) was obtained. The sensor ability to determine the polystyrene concentration in real samples was evaluated with the recovery of 98.4-113.3 % and reliable reproducibility (RSD < 9.72 %). For the quantitative measurement of the particle size of PS, SVD images exhibited that a linearity was obtained between Z'u(1)and lgD_ps in the particle size range of 0.08-20 μm. A good linearity with R² = 0.9877 was obtained when the concentration was 1 mg L^-1. The recovery was in the range of 100.8-118.0 % with the RSD < 6.38 %. Therefore, a novel method is established for the rapid detection of PS MPs.