Quantification of Poly(vinyl chloride) Microplastics via Pressurized Liquid Extraction and Combustion Ion Chromatography

Abstract

A reliable analytical method has been developed to quantify poly(vinyl chloride) (PVC) in environmental samples. Quantification was conducted via combustion ion chromatography (C-IC). Hydrogen chloride (HCl) was quantitatively released from PVC during thermal decomposition and trapped in an absorption solution. Selectivity of the marker HCl in complex environmental samples was ensured using cleanup via pressurized liquid extraction (PLE) with methanol at 100 °C (discarded) and tetrahydrofuran at 185 °C (collected). Using this method, recoveries of 85.5 ± 11.5% and a limit of quantification down to 8.3 μg/g were achieved. A variety of hard and soft PVC products could be successfully analyzed via C-IC with recoveries exceeding >95%. Furthermore, no measurable overdetermination was found for various organic and inorganic matrix ingredients, such as sodium chloride, sucralose, hydroxychloroquine, diclofenac, chloramphenicol, triclosan, or polychlorinated biphenyls. In addition, sediments and suspended particular matter showed PVC concentrations ranging up to 16.0 and 220 μg/g, respectively. However, the gap between determined polymer mass and particle masses could be significant since soft PVC products contain plasticizers up to 50 wt %. Hence, the results of the described method represent a sum of all chlorine-containing polymers, which are extractable under the chosen conditions.

Keywords: chlorine-containing polymers; environmental pollution; plastics; sediments; solvent extraction; suspended matter.

Figure 1

(a) Calibration curve for direct PVC combustion. (b) Calibration curve for PVC combustion after extraction. Calibration range was 0.005–5.0 mg/g.

Figure 2

PVC concentrations in suspended matter of the river Rhine obtained with filter nets (a) and a flow centrifuge (b).

Figure 3

Results of sediment samples from a habor basin of the river Main (concentration vs fraction size). It can be seen that the PVC concentration is mostly highest in the smallest fraction (10–50 μm).