Development of chemical digestion methods for the microplastics identification and quantification in various food matrices

Microplastic pollution being ubiquitous, studies on food contamination are becoming more numerous. However, certain food categories, such as dairy products, fruits, vegetables, legumes, cereals and their derivatives, and sugary products, have received little attention. This is partly due to the complexity of their biochemical compositions and the lack of appropriate sample preparation methods, which is why this study aims to develop and evaluate suitable chemical digestion methods. Various chemical reagents were applied to these matrices. This first step showed that the various protocols can digest most matrices, with the exception of rice, chocolate, apples, and carrots. The impacts of the protocols on the integrity of polymers (PA 6–6, polyethylene, polyester, polyvinyl chloride, and polystyrene) were evaluated. The second stage confirmed that 65% HNO 3 and 70% HClO 4 caused the degradation of certain polymers such as PA 6–6, PE, and PES, while 10% KOH and 30% H 2 O 2 did not degrade microplastics. • Digestion of various food matrices by chemical reagents (KOH, H 2 O 2 , HNO 3 , HClO 4 ). • Impact of different chemical reagents on various plastic polymers. • All type of foods were digested except rice, chocolate, apples, carrots and lentils. • 10% KOH and 30% H 2 O 2 are the only methods for recovering all tested plastic polymer. • 65% HNO 3 degrades PA, PE, PES and PVC, 70% HClO 4 degrades PA, PVC and PS.