Off-line analytical pyrolysis GC–MS to study the accumulation of polystyrene microparticles in exposed mussels

[Display omitted] •Off-line pyrolysis GC–MS quantified polystyrene in mussels exposed to microparticles.•Polystyrene microspheres efficiently extracted with toluene from KOH digestate.•Polystyrene was accumulated in digestive glands not in gills at ppm levels.•Lysosomal membrane stability affected at 10,000 particle liter water concentrations. An analytical procedure based on off-line analytical pyrolysis was utilized to study the bioaccumulation of polystyrene microspheres with different size (3 μm and 45 μm) by gills and digestive glands of Mytilus galloprovincialis exposed for 4 days at different concentrations of the polymer (3 μm: 0.015–1.5 μg L−1; 45 μm: 5−500 μg L−1). The mussel tissues were treated with 10 % KOH at 90 °C with good digestion efficiency (97 ± 1 %) and extracted with toluene. After evaporation the residue was pyrolysed at 500 °C with a resistively heated platinum filament. Pyrolysis products were trapped onto a charcoal cartridge, eluted with toluene and analysed by GC–MS under selected ion monitoring. Polystyrene concentrations were determined by the internal standard method from the peak areas of styrene. The procedure provided information on the effect of particle size, exposure level and tissue type on the bioaccumulation of polystyrene particles in terms of mass concentrations. Accumulation was observed in digestive glands, not in gills. The accumulation of larger particles in digestive glands increased with increasing concentrations of polystyrene in water and peaked at 14 ± 4 μg g−1. The reduction of lysosome membrane stability was observed for both particles size at a water concentration of 10,000 particles per litre, that corresponded to a lower mass concentration for the smaller particles. This study confirmed the capability of analytical pyrolysis to provide microplastic concentrations in terms of mass concentration in complex matrices.