Quantitative determination of poly(vinylpyrrolidone) by continuous-flow off-line pyrolysis-GC/MS

Poly(vinylpyrrolidone) (PVP) is a widely used and environmentally stable synthetic polymer whose occurrence in wastewater is likely. However, an appropriate method for identification and quantification of this polymer in environmental samples is still lacking. Hence, in this study an analytical method based on continuous-flow off-line pyrolysis-gas chromatography/mass spectrometry (pyrolysis-GC/MS) was developed to identify and quantify PVP in waste and surface water samples. Pyrolysis of commercial PVP, of some personal care products, of spiked water samples as well as of wastewater samples and river water samples was performed in a tube furnace at 500 °C under a continuous nitrogen flow. GC/MS was used for identification of specific degradation products, while GC-FID analysis was performed for quantitative determination. The concentration of PVP was calculated on the basis of the main pyrolytic product, N-vinylpyrrolidone (NVP). Very good linear correlation between initial amounts of PVP and released amounts of NVP was obtained and used as external calibration. The detected level of PVP in investigated personal care products was 6.4 (hair gel), 0.8 (laundry detergent) and 1.4% (tablets for throat disinfection). Spiked water samples, wastewater samples and river water samples were pre-extracted with hexane and diethyl ether prior to pyrolysis. It was found that the recovery of spiked samples was 94.6 ± 1.6% which indicated that pre-extraction did not provoke significant loss of polymer. Finally, application of the developed method on real environmental samples (river water) revealed that PVP was present in effluents from wastewater treatment plants in concentrations between 0.9 mg/L and 7 mg/L, as well as in river water affected by municipal sewage emissions with concentrations around 0.1 mg/L.