Direct molecular imprinting technique to synthesize coated electrospun nanofibers for selective solid-phase microextraction of chlorpyrifos.

Molecularly imprinted-electrospun nanofibers based on the use of poly(vinyl alcohol) were fabricated and used as a new sorbent for solid-phase microextraction of chlorpyrifos. The molecularly imprinted nanofibers were prepared by electrospinning and direct molecular imprinting of polymeric nanofibers. Poly(vinyl alcohol) was used as the functional and electrospun polymer. Chlorpyrifos was used as a template molecule, and glutaraldehyde as the cross-linker. Detection was performed by ion mobility spectrometry equipped with a secondary electrospray ionization source. The molecularly imprinted fiber has a selectivity and extraction efficiency better than the fiber fabricated using the conventional method of encapsulating MIP particles in electrospun nanofibers. Parameters affecting the extraction efficiency such as ionic strength, stirring rate, extraction time, and temperature were evaluated. The dynamic range of the method was in the range of 0.5-200 μg L-1 with the limit of detection of 0.1 μg L-1. The intra- and inter-day relative standard deviations of the method were 4 and 9%, respectively. The fiber-to-fiber reproducibility for three different fibers is 5%. The spiking recoveries from spiked apple, cucumber, and water samples were in the range of 82-112%. Graphical abstract Molecularly imprinted-electrospun nanofibers were fabricated based on the direct molecular imprinting technique and used as a new SPME fiber coating for selective extraction of chlorpyrifos from fruits and water samples prior its determination by secondary electrospray ionization-ion mobility spectrometry.