Electrospun nanofiber cloud for ultrafast solid phase micro-extraction of trace organics in water samples

In order to achieve ultrafast solid phase micro-extraction (SPME) of trace organics in water samples, the robust polyimide/polyvinylpyrrolidone (PI/PVP) composite nanofiber was prepared by electrospinning. Unlike the nonwoven electrospun membrane bulk widely used for SPME, the hydrophilic PI/PVP nanofibers here can be easily dispersed into and recovered from water sample like a cloud, so nanofiber cloud SPME (NC-SPME) was proposed in this work. The extraction performance of the NC-SPME method was evaluated using phthalates and organochlorine pesticides as model analytes. The extracted analytes were then desorbed by acetone and eventually quantified by gas chromatography-mass spectrometry (GC-MS). The extraction equilibrium was reached in 30 s for most of the phthalates and 2 min for organochlorine pesticides. While for bar-SPME, the equilibrium time was much longer than 2 h. At the extraction time of 5 min, the recoveries of phthalates and organochlorine pesticides were more than 34% and 52% by the NC-SPME method while they were less than 15% and 10% respectively by the bar-SPME method. In a word, the NC-SPME method presented significant advantages such as fast equilibrium and high recoveries compared to bar-SPME. For the phthalates analysis of real samples by NC-SPME, 5 mL of water sample was used for a 5-min extraction, linear range covered 1-2 orders of magnitude with correlation coefficients (r) higher than 0.99 and limits of detection (LODs) at ng/L levels for all of the tested water samples. This method will be useful for the rapid micro-extraction of other kinds of organics in water samples even biological fluid samples due to the stable composition, ultra-hydrophilic surface of PI/PVP nanofiber, and the biocompatible nature of PVP.