Process optimization on extraction and isolation of microplastics in zebrafish using response surface methodology

Abstract:

Recently, with the increase of global plastic production, microplastic accumulation in aquatic environments is increasing. This seriously endangers the living environment and aquatic organism health. Furthermore, it endangers human health through the food chain. Microplastic detection in aquatic products is fundamental to understanding microplastics. Using digestive compounds to extract and separate microplastic from aquatic organisms is an effective means. It is particularly important to choose the correct digestive compounds and conditions. In the present experiment, zebrafish was used as an aquatic model, and polystyrene was used as the raw material. Zebrafish and microplastics were mixed in proportion. The microplastics were separated and extracted using different digestive compounds. Initially, 10% KOH, 30% H2O2, 69% HNO3, and trypsin were selected based on digestibility, recovery rate, Raman spectroscopic analysis, and scanning electron microscopy. The results showed that 30% H2O2 has the lowest digestibility and can change its chemical structure. Trypsin has the lowest recovery rate. Scanning electron microscopy and stereoscopic microscopy showed that 69% HNO3 changed the microplastics color and corroded the surface. Therefore, 10% KOH solution was selected as the optimal digestive compound. Then, the optimal digestion conditions of KOH solution were determined using single factor and Box-Behnken design tests. The results showed that the optimum digestion conditions were: concentration – 4%, temperature – 47℃, time – 20 h, with 97.38% digestibility. The digestive compounds and conditions screened in this study could significantly improve zebrafish digestion efficiency. The results provided a new method for the digestion of aquatic products and further detection and analysis of microplastics in aquatic products.