A sandwiched format microfluidic setup using electrospun hollow nanofibers sheets as efficient and sensitive microextractive phases

In the present work, an inexpensive microfluidic device from polymethyl methacrylate (PMMA) was constructed by laser engraving technique. The device consisted of a central chip unit with an aligned micro channel (1mm depth and 0.3 mm width), acting a key role in extraction process. Both sides of the micro channel were pushed with two similar polyamide/titania (PA/TiO2) hollow nanofiber sheets as extractive phases [1]. Finally, two other PMMA units were placed on both sides and screwed up tightly. The inlet and outlet of the device were connected to two tubes made of polyether ether ketone (PEEK). A peristaltic pump was used to deliver both sample and desorption solvent through micro channel. Finally, 2μL of the collected solvent containing triazines as target analytes were injected into the gas chromatography injection port. The surface characteristic and morphology of the electrospun core–shell hollow nanofibers were investigated using scanning electron microscopy, exhibiting the homogeneity and porosity in the synthesized hollow nanofibers. Also, the energy dispersive X-ray analysis proved the presence of titanium in the structure of the nanofibers. In addition, Fourier transform infrared spectra proved the chemical structure of the nanofibers. Influencing parameters on the extraction efficiency and signal to noise enhancement including the type of the extraction phase, sample and desorption solvent volume and flow rate, and the type of desorption solvent were investigated and optimized [2]. Eventually, the developed method was validated using gas chromatography–mass spectrometry. At the optimum conditions, the relative standard deviation values for a water samples spiked with the selected triazines at 0.2 and 10 ng mL-1 were 6.1–6.6% (n = 3) and the limits of detection for the target compounds were between 0.01 and 0.03 ng mL−1. The obtained calibration graphs were linear in the concentration range of 0.2-50 ng mL-1 for atrazine, and two separate linear ranges for both ametryn (0.1-10 and 20-500 ng mL-1) and terbutryn(0.1-10 and 20-500 ng mL-1). Relative recoveries were between 89-98% and the regression coefficients for the target analytes were satisfactory (R2= 0.9969-0.9991).