Validation
For validation of the extraction procedure, recoveries were deter-
mined using PE (as surrogate for light polymers, ρ = 0.92 g/ml, particle
sizes: 45–100 μm: 5%, 100–500 μm: 66%, 500–900 μm: 29%) and PVC (as
surrogate for heavy polymers, ρ = 1.4 g/ml, particle sizes: 45–100 μm:
4%, 100–300 μm: 96%;) powder spiked in 25 L of water.