Carbon nanotubes, activated carbon and Oasis HLB as sorbents of passive samplers for extraction of selected micropollutants — Comparison of sampling rates and extraction efficiency

Currently, the POCIS (passive organic chemical integrative samplers) are promising tools for future regular monitoring of the aquatic environment. As the commercially available POCIS has its limitations, innovative solutions, and modifications of conventionally used samplers are sought. For this reason, this study compares the sampling rates (Rs) and extraction efficiencies (EE) of ketoprofen, naproxen, flurbiprofen, diclofenac, imipramine, desipramine, carbamazepine, methotrexate, bisphenol A, 17-β-estradiol, 17-α-ethinylestradiol, p-nitrophenol and 3,5-dichlorophenol by kinetic passive samplers containing various types of sorbents. Five types of multi-walled carbon nanotubes, activated carbon and Oasis HLB were used as receiving phases. Additionally, the influence of environmental factors such as: water salinity, water pH, dissolved humic acids and the real water matrix (treated and untreated sewage) on the Rs and EE values was investigated. The advantage of using unmodified multi-walled carbon nanotubes with an outer diameter < 8 nm in passive sampling devices (8-CNTs-PSD) compared to other used sorbents was demonstrated. Using 8-CNTs, sampling rates in the range of 0.037–0.132 L d−1 and extraction efficiencies in the range of 46–105% (excluding methotrexate) were obtained, which were independent of environmental factors. The collected results show that 8-CNTs-PSDs are the best choice for the future monitoring of the target analytes in the aquatic environment compared to the other tested samplers.