Three-dimensional nanofiber scaffolds are superior to two-dimensional mats in micro-oriented extraction of chlorobenzenes

Three-dimensional (3D) polyamide scaffolds were fabricated by applying a solvent bath as the collecting element. Electrospun nanofibers were immersed into the solvent bath to give a material with a laminated 3D texture. In parallel, 2D nanofibers were synthesized and utilized as microextractive phases in a needle trap device to compare the capabilities of 2D and 3D materials in terms of headspace extraction of various chlorobenzenes (chlorobenzene, 1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,2,4-trichlorobenzene and 1,2,3,4-tetrachlorobenzene). The results demonstrate the superiority of 3D nanofibrous scaffolds over 2D mats. The porosity, morphology, and thermal stability of the 3D scaffolds were characterized using FT-IR, scanning electron microscopy, confocal laser scanning microscopy and thermogravimetric analysis. The CLSM images were reconstructed and analyzed by Image J software, and eventually the enhancement of porosity using 3D scaffolds was confirmed. The type of solvent bath, polyamide solution concentration and other parameters were optimized. Following thermal desorption of the chlorobenzenes, they were quantified by GC-MS. Under optimum conditions, the calibration plots cover the 0.004-1.0 pg mu L-1 concentration range and the limits of detection are in the range from 0.8-3 pg mL(-1). The relative standard deviations (RSDs) are between 3 and 8% and 3-10% (n = 3) at spiking levels of 200 and 1000 ng L-1, respectively. The RSDs for the needle-to-needle repeatability are < 15% (for n = 3). This needle trap microextraction method was applied to the analysis of river water, sea water, and of inlet water of a water treatment plant.