Supramolecular solvents based on hydrophobic natural deep eutectic solvents and primary amines for preconcentration and determination of enrofloxacin in milk.

In this work, coacervation in primary amines solutions with hydrophobic natural deep eutectic solvents based on terpenoids and carboxylic acids was demonstrated for the first time. A liquid-phase microextraction approach was developed based on supramolecular solvent formation with primary amine acting as amphiphile and hydrophobic deep eutectic solvent making up mixed vesicles and serving as coacervation agent. Such supramolecular solvents could be used to separate wide range of substances from different aqueous media, such as food products, biological liquids and wastewaters.

Primary amine citrate-based supramolecular designer solvent: Preconcentration of ochratoxin A for determination in foods by liquid chromatography.

Background: Supramolecular solvents are nanostructured liquids that are separated from colloidal solutions of amphiphilic compounds as a result of self-assembly of amphiphiles and coacervation under changing conditions. They are considered to be designer solvents as their properties can be tailored to a specific analytical task by controlling the conditions of their formation (amphiphile, coacervation inducer, medium, concentration of components). The discovery of new extraction systems based on supramolecular solvents and their application to relevant analytical tasks are of great importance for the advancement of environmentally-friendly sample preparation.

Deep eutectic solvents with low viscosity for automation of liquid-phase microextraction based on lab-in-syringe system: Separation of Sudan dyes.

In the work limitations of deep eutectic solvents in the flow-based analysis are discussed. Deep eutectic solvents based on terpenes and fatty acids with low viscosity were studied as extraction solvents for liquid-liquid microextraction into a lab-in-syringe system for the first time. As a result an automated deep eutectic solvent-based microextraction approach was proposed.

Liquid-liquid microextraction with hydrophobic deep eutectic solvent followed by magnetic phase separation for preconcentration of antibiotics.

This study describes a miniaturized approach for liquid-liquid microextraction based on mass transfer into low volume of deep eutectic solvent and magnetic phase separation, using specially produced magnetic chromium dioxide nanoparticles with a hydrophobic surface layer of fatty acids. The nanoparticles modified with fatty acid helped to recover low volumes of viscous hydrophobic deep eutectic solvent-based extract reproducibly and easily (up to 10 μL) in a microextraction procedure with the application of magnetic forces. It was demonstrated that the collector properties depend on nanoparticles' surface and magnetic characteristics.

A synergistic effect of hydrophobic deep eutectic solvents based on terpenoids and carboxylic acids for tetracycline microextraction.

Hydrophobic deep eutectic solvents were investigated for tetracycline microextraction. It was found that a deep eutectic solvent consisting of thymol and octanoic acid provided a synergistic effect on tetracycline extraction. In this paper, a novel liquid-liquid microextraction procedure for the HPLC-DAD determination of tetracyclines in milk samples was proposed.

Supramolecular solvents formation in aqueous solutions containing primary amine and monoterpenoid compound: Liquid phase microextraction of sulfonamides.

A phenomenon of supramolecular solvents formation in aqueous solutions containing primary amine and monoterpenoid compound is presented for the first time. A novel supramolecular solvent-based liquid phase microextraction was developed. In an aqueous phase primary amine formed isotropic solution due to formation of amphiphile supramolecular assembly.

An automated in-syringe switchable hydrophilicity solvent-based microextraction.

A fully automated in-syringe switchable hydrophilicity solvent-based microextraction approach was suggested for the first time. Di-(2-ethylhexyl)phosphoric acid was investigated as a novel switchable hydrophilicity solvent. The microextraction procedure implemented into a syringe pump included dissociation of the extractant in alkaline sample solution resulting in homogeneous solution formation followed by in situ organic phase generation by acidification and its separation.

Stir membrane liquid phase microextraction of tetracyclines using switchable hydrophilicity solvents followed by high-performance liquid chromatography.

A novel approach for stir membrane liquid phase microextraction of tetracyclines from biological fluids was developed. The microextraction procedure assumed in situ formation of microdroplets of a hydrophobic medium-chain fatty acid (extraction solvent) from homogeneous sample solution containing water-soluble medium-chain fatty acid salt by acidification and simultaneous analytes extraction and organic phase separation into pores of stir membrane disk. Obtained large surface area between the extraction solvent and aqueous phase and high porosity of the membrane provided fast extraction and phase separation (extraction time - 5 min) and reducing extraction solvent volume to the order of several µL.

Homogeneous liquid-liquid microextraction based on primary amine phase separation: A novel approach for sample pretreatment.

A homogeneous liquid-liquid microextraction procedure based on primary amine phase separation was developed as a novel approach for the pretreatment of biological fluids. The procedure assumes primary amine dissolution in the aqueous sample phase, resulting in the creation of a homogeneous sample solution followed by phase separation and analyte extraction in the presence of a polar, water-miscible organic solvent. The phenomenon of primary amine phase separation from homogeneous aqueous solution in the presence of a polar, water-miscible organic solvent was studied in detail and applied for separation and preconcentration in chemical analysis for the first time.

Tin oxide nanoparticles modified by copper as novel catalysts for the luminol-HO based chemiluminescence system.

In this study, SnO2 nanoparticles modified by copper were found to greatly enhance the chemiluminescence intensity of the luminol-H2O2 system for the first time. The developed approach was applied for the determination of H2O2 as a proof-of-concept example.

A chemiluminescence method for screening of fluoroquinolones in milk samples based on a multi-pumping flow system.

An automated and miniaturized chemiluminescence method for screening of fluoroquinolones in milk samples was proposed. The method was based on magnetic dispersive micro-solid phase extraction of analytes followed by the chemiluminescence determination of the total fluoroquinolones content using a multi-pumping flow system. In the developed method, Zr-Fe-C magnetic nanoparticles were used as an efficient sorbent for separation of fluoroquinolones from sample matrix.

An automated salting-out assisted liquid-liquid microextraction approach using 1-octylamine: On-line separation of tetracycline in urine samples followed by HPLC-UV determination.

An automated salting-out assisted liquid-liquid microextraction (SALLME) procedure based on a flow system was developed as new approach for pretreatment of complex sample matrix. In this procedure 1-octylamine was investigated as novel extractant for the SALLME. The procedure involved aspiration of the 1-octylamine and sample solution into a mixing chamber of a flow system followed by their air-bubble mixing resulting to isotropic solution formation.

A novel flow injection chemiluminescence method for automated and miniaturized determination of phenols in smoked food samples.

An easily performed fully automated and miniaturized flow injection chemiluminescence (CL) method for determination of phenols in smoked food samples has been proposed. This method includes the ultrasound assisted solid-liquid extraction coupled with gas-diffusion separation of phenols from smoked food sample and analytes absorption into a NaOH solution in a specially designed gas-diffusion cell. The flow system was designed to focus on automation and miniaturization with minimal sample and reagent consumption by inexpensive instrumentation.

Switchable hydrophilicity solvent membrane-based microextraction: HPLC-FLD determination of fluoroquinolones in shrimps.

A switchable hydrophilicity solvent membrane-based microextraction (SHS-MME) strategy for simple and highly-available sample pretreatment of complex matrices has been proposed. The SHS-MME procedure based on extraction of target analytes from an aqueous sample into a porous hydrophobic membrane impregnated with a switchable hydrophilicity solvent (SHS) followed by SHS ionization and back-extraction of the analytes in alkaline acceptor solution. The medium-chain fatty acids were investigated as SHS for the SHS-MME of fluoroquinolones (fleroxacin, lomefloxacin, norfloxacin and ofloxacin).

Automated alkaline-induced salting-out homogeneous liquid-liquid extraction coupled with in-line organic-phase detection by an optical probe for the determination of diclofenac.

A fully automated alkaline-induced salting-out homogeneous liquid-liquid extraction (AI-SHLLE) procedure coupled with in-line organic-phase detection by an optical probe has been suggested. Diclofenac was used as a proof-of-concept analyte. The method is based on the oxidation of diclofenac with potassium ferricyanide in an alkaline medium followed by separation of the acetonitrile phase from the homogeneous sample solution and simultaneous extraction of the derivative.

A fully automated effervescence-assisted switchable solvent-based liquid phase microextraction procedure: Liquid chromatographic determination of ofloxacin in human urine samples.

A novel fully automated effervescence-assisted switchable solvent-based liquid phase microextraction procedure has been suggested. In this extraction method, medium-chain saturated fatty acids were investigated as switchable hydrophilicity solvents. The conversion of fatty acid into hydrophilic form was carried out in the presence of sodium carbonate.