ZnO nanopatricles/polyamide nanocomposite coated on cellulose paper as a novel sorbent for ultrasound-assisted thin film microextraction

In this work, a novel thin film microextraction (TFME) 1, 2 method was developed using ZnO nanoparticles (ZnO NPs) incorporated into polyamide (PA) nanocomposite. In this regard the ex-situ prepared ZnO NPs 3 was dispersed into PA solution and the obtained solvent blend was deposited onto cellulose paper applying solvent exchange method. The characterization of prepared ZnO NPs/PA nanocomposite was performed applying energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The prepared thin film based on ZnO NPs/PA nanocomposite was employed for ultrasound assisted thin film microextraction (USA-TFME) of some organophosphorous pesticides (OPPs) as model compounds including fenthion, chlorpyrifos, fenithrothion, phosalone, edifenphos and ethion in environmental water samples followed by gas chromatography-flame ionization detector (GC-FID) determination. TFME is a relatively new approach based on membrane solid phase microextraction (SPME) in sample preparation techniques which has exhibited more advantages over SPME such as small thickness of the extraction phase, a larger surface area-to-volume ratio, higher extraction rate and shorter equilibration time. Ultrasonic (US) radiation can be used in microextraction techniques as a powerful tool to increase the speed of the mass transfer process of the solutes towards the adsorbent surface 4, leading to enhance of the extraction efficiency in a shorter duration time 5. Important parameters influencing the extraction and back-extraction steps of USA-TFME were optimized applying orthogonal array Taguchi design. The developed methods limits of detection (LODs) were in the range of 0.05 to 0.3 ng mL−1 and its linear dynamic ranges (LDRs) were 0.2-1000, 0.3-1000 and 1-1000 ng mL-1 for all analytes. The method precision (RSD %) with three replicates experiments was in the range of 2.1 to 9.8% using spiked distilled water (100 ng mL−1).