Preparation of Ferrofluid from Adipic Acid Coated Magnetic Nanoparticles and Hydrophobic Deep Eutectic Solvent Used in Dispersive Micro-Solid-Phase Extraction: Application for the Pre-Concentration and Determination of Clozapine in Biological Samples.

The aim of the present study is the preparation of a novel magnetic ferrofluid (FF) based on a hydrophobic deep eutectic solvent (DES), which is used for the extraction of trace quantities of clozapine from biological samples. For this purpose, a highly stable FF was prepared through the combination of adipic acid-coated magnetic nanoparticles (MNPs) plus tetraethylammonium chloride/thymol hDES without an additional stabilizer. These solvents were synthesized by the available and less-toxic materials, which is the appropriate option to support the solvents for the preparation of FF.

Development of magnetic solid phase extraction based on magnetic chitosan-graphene oxide nanoparticles and deep eutectic solvents for the determination of flavonoids by high performance liquid chromatography.

An environmentally friendly magnetic solid phase extraction method was developed based on magnetic chitosan-graphene oxide nanoparticles and deep eutectic solvents (DESs) for the pre-concentration and isolation of flavonoids (apigenin, morin, naringenin, and quercetin) of natural orange juice, commercial apple juice, onion juice, green tea, and natural apple juice samples. DESs hydrophilic and π-π interactions could increase the extraction performance. The immobilization of chitosan-graphene oxide on the surface of FeO nanoparticles improved their chemical properties and mechanical stability.

Nanofluid of magnetic-activated charcoal and hydrophobic deep eutectic solvent: Application in dispersive magnetic solid-phase extraction for the determination and preconcentration of warfarin in biological samples by high-performance liquid chromatography.

In this study, for the first time, nanofluid of magnetic-activated charcoal and hydrophobic deep eutectic solvent (AC@Fe O -DES) based dispersive magnetic solid-phase extraction was successfully applied for the determination and preconcentration of warfarin in plasma and urine samples. The hydrophobic DES was prepared by mixing tetramethylammonium chloride (as hydrogen bond acceptor) and thymol (as hydrogen bond donor) and acted simultaneously as both carrier and stabilizer for magnetic nanoparticles. In this method, the nanofluid as a new extraction solvent was rapidly injected into the aqueous sample, which led to improvement of the mass transfer of the analytes into the sorbent and reduction of the extraction time.

Determination of Morin and Quercetin in Fruit Juice Samples using Air-Assisted Liquid-Liquid Microextraction Based on Solidification of Floating Organic Droplet and HPLC-UV.

In this study, a rapid and efficient method has been used for the extraction and determination of morin and quercetin in fruit juice samples based on air-assisted liquid-liquid microextraction based on solidification of floating organic droplet and HPLC-UV. The effects of 7 important parameters on the extraction recovery were examined and were optimized by Plackett-Burman design and Central Composite design. According to the Plackett-Burman design results, ionic strength of the sample solutions, the aspiration/dispersion cycles, and the rate and time of centrifuge did not show significant effects on the extraction of morin and quercetin.

Polyvinylidene difluoride film with embedded poly(amidoamine) modified graphene oxide for extraction of chlorpyrifos and diazinon.

An effective, sensitive, relatively fast, and cost-effective method was developed to determine two types of selected organophosphorus pesticides (OPPs) including diazinon and chlorpyrifos in apple, peach, and four different water samples (river, sea, well, and agriculture wastewater samples) through applying poly(amidoamine)@graphene oxide-reinforced polyvinylidene difluoride thin-film microextraction (PAMAM@GO-PVDF-TFME). The extracted analytes were desorbed via organic solvent and determined using high-performance liquid chromatography-ultraviolet detection (HPLC-UV). The strong interactions between the sorbent and selected analytes (coordination bonds, intermolecular hydrogen bonding, π-π interactions, and hydrophobic effects) made this TFME capable of high extraction performance and capacity.