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Dispersive liquid–liquid microextraction based on solidification of floating organic drop method is a highly efficient method optimized for the first time in the determination of trace levels of ibuprofen, naproxen, diclofenac, and ketoprofen in water samples. Several important parameters affecting the dispersive liquid–liquid microextraction based on solidification of floating organic drop (extraction solvent, ionic strength, pH, dispersion solvent, vortex, and centrifugation times) were studied and optimized using a univariate optimization strategy. High‐performance liquid chromatography coupled with a photo‐diode array detector was used after the sample preparation. Limits of detection and quantification were in the range of 0.15–0.32 and 0.48–0.98 μg/L, respectively. Moreover, the linear dynamic range was up to 1000 μg/L and determination coefficient was higher than 0.9949. Recoveries in all water samples at two spiking levels (20 and 50 μg/L) were between 80.5 and 102.8% for all the pharmaceuticals. The intra‐ and interday (n = 5) precision were below 9.4%. Using dispersive liquid–liquid microextraction based on solidification of floating organic drop as a method for the extraction of pharmaceuticals from the aquatic environment is simple, rapid, environmentally friendly, and opens a new door for applications in this field where preconcentration is almost always required. [ABSTRACT FROM AUTHOR]

Magnetic cellulose nanoparticles (MCNPs) were used for the first time as sorbents for stir bar-sorptive dispersive microextraction (SBSDME). The main experimental parameters involved in the SBSDME process that affect extraction (i.e. amount of MCNPs, ionic strength, pH, extraction and back-extraction time) were investigated. The method was applied to the determination of nine polychlorinated biphenyls (PCBs) in fruit juice samples by gas chromatography–mass spectrometry (GC-MS). Under the optimized conditions, a good linearity was obtained in a concentration range of 10–1000 ng mL−1 with determination coefficients over 0.9945. Limits of detection and quantification for all target PCBs were in the range 2.1–54 ng L−1 and 7.0–180 ng L−1, respectively. Intra-day precision ranged from 1.7% to 8.8% and inter-day precision from 3.4% to 9.3% RSD. The enrichment factors of the analytes were from 74.6 to 98.2. The MCNPs can be reused up to 5 times. The method was applied to commercial orange and pineapple juices (n = 5), where concentrations were below the limits of detection. Recoveries from 70.4 to 108.0% were obtained by applying the method for the analysis of spiked fruit juice samples at 1 and 2 ng mL−1 concentration levels. The use of cellulose makes this approach environmentally friendly and the magnetism of the resulting sorbent in conjunction with SBSDME provides ease of handling and saving of time. Image 1 • First time magnetic cellulose nanoparticles are used as sorbents in SBSDME. • Application to the control of nine PCBs in commercial juice samples. • Low amount of sorbent and straightforward operation. • Preconcentration factor up to 100 and quantitative recoveries were achieved. • The method is cost-effective, easy to operate and environmentally friendly. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • First IL-DLLME method for determination of cortisone and cortisol in saliva. • The method provides high selectivity and enrichment factors to achieve biological levels. • The IL enables extraction and concentration of cortisone and cortisol in one step. • The method needs no sophisticated instrumentation and is environmentally friendly. Abstract Ionic liquid dispersive liquid–liquid microextraction (IL-DLLME) was used for the first time for the extraction and preconcentration of cortisone and cortisol from human saliva samples. This approach allows the determination of both compounds by liquid chromatography (LC) with ultra-violet/visible (UV/Vis) detection at physiological levels. The IL 1-butyl-3-methylimidazolium hexafluorophosphate [C 4 MIM][PF 6 ] and methanol (MeOH) were used as extraction and dispersive solvents, respectively. The parameters that affect extraction (ionic strength, pH, amount of IL, volume of dispersive solvent, vortex and centrifugation time) were optimized. Limits of detection were 0.11 (cortisone) and 0.16 μg L−1 (cortisol) and enrichment factors of 5.0 (cortisol) and 6.3 (cortisone) were achieved. Recoveries from 83.3 ± 1.6 to 115.8 ± 3.0% were obtained for the extraction of the target analytes in spiked human saliva samples. Intraday and interday precision, expressed as relative standard deviation, was below 4.2 and 7.8% for cortisone and cortisol, respectively. The method was successfully applied to the determination of cortisone and cortisol in saliva from healthy volunteers (n = 9) in the morning and in the evening. The method is simple, faster, and more environmentally friendly than the current ones. [ABSTRACT FROM AUTHOR]

Magnetic cellulose nanoparticles (MCNPs) coated with 1-butyl-3-methylimidazolium hexafluoro phosphate [C 4 MIM][PF 6 ] ionic liquid (IL) through electrostatic interactions are proposed for the first time as sorbents in a magnetic solid phase extraction (MSPE) method for the determination of paracetamol (PAR), ibuprofen (IBU), naproxen (NAP) and diclofenac (DIC) in natural waters. The parameters that affect adsorption (dispersive solvent, amount of IL, pH and salt content) and desorption (desorption solvent, type of energy and time) were studied. The values that provided the maximum adsorption efficiency and extraction recovery were selected as optimum conditions for adsorption and desorption, respectively. Under the optimum conditions, the adsorption and desorption of all analytes was simultaneous and quantitative. High performance liquid chromatography (HPLC) with ultra violet (UV) and fluorescence (FL) detector was used after the sample preparation. The precision, expressed as relative standard deviation was between 1.4 and 7.6%. Limits of detection and quantification were in the range 3.2–7.2 μg L − 1 and 11–24 μg L − 1 , respectively. Moreover, the proposed method provides enrichment factors from 29.0 to 34.2. Recovery studies on 10 mL of spiked tap, river and dam water samples at 50 and 100 μg L − 1 were carried out. The extraction recoveries were from 85 to 116%, and were in a comparable range regardless of the type of water. The method is simple, rapid, and environmentally friendly. [ABSTRACT FROM AUTHOR]

Magnetite (Fe3O4) nanoparticles were modified with nanocellulose and are showed to be a useful sorbent for magnetic solid-phase extraction of mercury species. Speciation analysis was performed by using gas chromatography coupled to atomic fluorescence detection (GC-pyro-AFS). The magnetic properties of the sorbent make this approach simple and rapid, and the use of a renewable and biodegradable nanomaterial (nanocellulose) makes it environmentally friendly. The factors that affect adsorption (pH value, amount of nanomaterial, time, volume of sample) and desorption (solvent, time) have been optimized. Both desorption and derivatization of mercury species were performed in a single step. This reduces considerably the sample preparation time. Under the optimized conditions, the limits of detection are 4.0 pg mL−1 for monomethylmercury and 5.6 pg mL−1 for inorganic mercury. The repeatability and reproducibility are satisfactory. The method enables inorganic mercury and monomethylmercury to be simultaneously extracted, with preconcentration factors up to 300. The potential interferences of organic matter and/or co-existing ions were also investigated using synthetic waters. The procedure was applied to the analysis of tap water and river water samples with different characteristics from a mercury polluted area (Almadén, Spain). The extraction recoveries ranged from 81 to 98% regardless of the type of water, which demonstrates the applicability of the method. This is the first time that this kind of sorbent is used for trace metal speciation. [ABSTRACT FROM AUTHOR]