Selection and optimization of a protocol for extraction of microplastics from Mactra veneriformis

Nowadays, several digestion protocols have been employed to extract microplastics from marine biota. However, the appropriate protocol and its optimal operating conditions to eliminate the clam Mactra veneriformis tissues have never been investigated. In this study, two synchronous phases were taken to select the compromise elimination protocol which was efficient in digesting biological materials with little effect on identification of the tested plastic polymers. Furthermore, the protocol from compromising results between two phases was optimized by an orthogonal experiment to determine the best operating conditions. Then, an application of the optimization protocol to investigate microplastics pollution in commercial clams was conducted. According to our results, 10% KOH showed fairly well digestion efficiency and little effect on identification of the tested microplastics. Furthermore, best operating conditions were demonstrated as treating clam tissues with 1:5 (M:V) of 10% KOH solution, incubating at 60 °C, shaking at 30 rpm for 12 h. In China, commercial clams were found contaminated with widespread microplastics pollution (3.50 ± 1.35 items/g). These problems should be further investigated and assessed due to the increased consumption as seafoods.