Preparation and characterization of magnetic Wells-Dawson heteropoly acid nanoparticles for magnetic solid-phase extraction of aromatic amines in water samples.

In this work, aminopropyl modified silica-coated magnetite nanoparticles with Wells-Dawson heteropoly acid (P2W17Fe@APSCMNPs) was first synthesized and underwent highly efficient magnetic solid-phase extraction (MSPE) of aromatic amines from aqueous samples. The resulted nanomaterials were characterized with different physicochemical techniques such as Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). Aniline, N,N-dimethylaniline, o-toluidine and 3-chloroaniline were selected as target compounds. The sample quantification was carried out using gas chromatography-flame ionization detector (GC-FID). Under optimal working conditions, the developed method showed good linearity (R>0.9912) in the range of 0.01-100ngmL-1. The method displays detection limits (at an S/N ration of 3) in the range from 0.003 to 0.01ngmL-1, and the limits of quantification (at an S/N ratio of 10) are between 0.01 and 0.04ngmL-1. The enrichment factors (EFs) were in the range of 75-113. Relative standard deviations (RSDs) are 4.8-8.3%. The applicability of the developed method was examined by analyzing different water samples (river water, tap water, well water and wastewater) and the relative recovery values for the spiked water samples were found to be in the range of 90.7-99.8%.

Magnetic nanoparticles coated with poly(p-phenylenediamine-co-thiophene) as a sorbent for preconcentration of organophosphorus pesticides.

The authors describe the preparation of Fe3O4 nanoparticles coated with poly(p-phenylenediamine-co-thiophene). The resulting nanoparticles (NPs) are shown to be viable sorbents for use in magnetic solid-phase extraction (MSPE) of organophosphorus pesticides (OPPs). The coated NPs were characterized by BET, FTIR, scanning electron microscopy and transmission electron microscopy. Following sorption of OPPs and subsequent desorption with dichloromethane, the OPPs were quantified by GC in combination with FID. Under optimal conditions, the preconcentration factors range from 118 to 163. Other figures of merit include (a) a linear response between 0.3 and 500 ng mL-1; (b) detection limits (at an S/N ratio of 3) between 0.1 and 0.3 ng mL-1, and (c) a precision (for n = 5) between 4.7 and 8.1% at concentration levels of 1, 10 and 100 ng mL-1). The nanocomposites can be reused up to 8 times. The method was applied to the analysis of spiked environmental water samples and fruit juices and gave relative recoveries in the range of 88.1 to 99.2%. Graphical abstract Schematic presentation of the synthesis of core-shell magnetic nanoparticles (MNPs) of the type poly(pPDA-co-Th)@Fe3O4, and their application as a sorbent for magnetic solid-phase extraction (MSPE) of organophosphorus pesticides.

Synthesis of nano-hydroxyapatite sorbent for microextraction in packed syringe of phthalate esters in water samples.

An easy alkoxide-based sol-gel method using Ca(NO3)2·4H2O and tri-ethyl phosphate (PO(OC2H5)3; TEP) precursors employed to synthesize nano-hydroxyapatite (HAP). The structural characterization of samples was studied using XRD, TEM and elemental analysis of SEM. Scherrer and Williamson-Hall equations were applied to measurement of the crystallite size distributions and micro-strain of the synthesized HAP powder. The synthesized HAP nanoparticles were applied as an efficient sorbent for the microextraction in packed syringe (MEPS) of phthalate esters (PAEs) from water samples. Separation and determination of the PAEs were performed by gas chromatography-flame ionization detection (GC-FID). Several variables affecting the extraction efficiency of the analytes i.e., desorption solvent, volume of desorption solvent and number of extraction cycles were investigated and optimized. Under optimized conditions, the calibration curves were linear (R > 0.9916) in the concentration range of 0.05-100 ng mL-1. The method displays detection limits (at an S/N ration of 3) in the range from 0.02 to 0.1 ng mL-1, and the limits of quantification (at an S/N ratio of 10) are between 0.07 and 0.25 ng mL-1. Relative standard deviations (RSDs) for intra- and inter-day precision are 4.8-8.3%, and 6.1-8.5%, respectively. The applicability of the developed method was examined by analyzing different water samples (river water, bottled mineral water and tap water) and the relative recovery values for the spiked water samples were found to be in the range of 85.5-99.2%.