Dilute-and-shoot approach combined with in-situ formed metal-containing ionic liquids for extraction of benzophenone and related compounds from açaí-based food products

For the first time, benzophenone and related compounds were investigated in açaí-based food products. An extraction method based on the dilute-and-shoot approach, combined with the use of in-situ formed metal-containing ionic liquids (MCILs) followed by high-performance liquid chromatography, was developed and validated. A nickel and cobalt-based MCIL, in addition to the ratio of MCIL to lithium bis[(trifluoromethyl)sulfonyl]imide salt ([Li+][NTf2-]) for the ensuing metathesis reaction, were optimized. Parameters of the in-situ formed MCIL step, namely, the amount of MCIL, centrifugation time, and dilution step, were analyzed using a multivariate optimization approach, including central composite rotatable design and Derringer and Suich's tool. Optimum extraction performance was achieved using 50.98 mg of nickel-based MCIL and a MCIL to ([Li+][NTf2-]) ratio of 1:3 (m/m), a centrifuge time of 22 min, and 10.53 mL of water for the dilution step. This condition was used to perform analytical validation, which yielded satisfactory results with R2 ≥ 0.995, limits of detection (LOD) ranging from 0.0025 to 0.5 mg kg-1, and limits of quantification (LOQ) between 0.008 and 1.5 mg kg-1. The recovery rate ranged from 87 % to 107 % and precision values (as percent relative standard deviation) were equal or lower than 13 %. The validated method was applied to 25 samples of açaí-based food products purchased from Brazil and the United States. None of the samples showed analyte concentration levels above the LOD. The method's suitability was demonstrated for future monitoring of complex samples, such as foodstuffs.

Comparing the extraction performance of cyclodextrin-containing supramolecular deep eutectic solvents versus conventional deep eutectic solvents by headspace single drop microextraction

A headspace single drop microextraction (HS-SDME) method coupled with high performance liquid chromatography was developed to compare the extraction of eighteen aromatic organic pollutants from aqueous solutions using cyclodextrin-based supramolecular deep eutectic solvents (SUPRADESs) and alkylammonium halide-based conventional deep eutectic solvents (DESs). Different derivatives of beta-cyclodextrin (β-CD) were employed as hydrogen bond acceptors (HBA) in SUPRADESs and the extraction performance investigated. SUPRADES comprised of the 20 wt% native β-CD HBA provided the highest enrichment factors of analytes compared to SUPRADESs comprised of other derivatives of β-CD (random methylated β-cyclodextrin, heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin, and 2-hydroxypropyl β-cyclodextrin). In addition, native β-CD and its derivatives were dissolved in the neat DESs and their effect on the extraction of analytes examined. Dissolution of 20 wt% native β-CD in the choline chloride ([Ch⁺][Cl^-]):2Urea DES resulted in a significant increase in the extraction efficiencies of target analytes compared to the neat [Ch⁺][Cl^-]:2Urea DES. Under optimum conditions, the extraction method required a solvent microdroplet of 6.5 μL, 1000 rpm stir rate, 30% (w/v) salt concentration, and a temperature of 40 °C. The tetrabutylammonium chloride: 2 lactic acid DES resulted in the highest enrichment factors while the [Ch⁺][Cl^-]:2Urea DES had the lowest for most of the analytes among the evaluated solvents. The method provided limits of detection (LODs) down to 35 μg L^-1. Furthermore, the developed method was applied for the analysis of spiked tap and lake water, where relative recoveries ranging from 83.7% ̶ 119.7% and relative standard deviations lower than 19.2% were achieved.

Miniaturized analytical methods for determination of environmental contaminants of emerging concern - A review

The determination of contaminants of emerging concern (CECs) in environmental samples has become a challenging and critical issue. The present work focuses on miniaturized analytical strategies reported in the literature for the determination of CECs. The first part of the review provides brief overview of CECs whose monitoring in environmental samples is of particular significance, namely personal care products, pharmaceuticals, endocrine disruptors, UV-filters, newly registered pesticides, illicit drugs, disinfection by-products, surfactants, high technology rare earth elements, and engineered nanomaterials. Besides, an overview of downsized sample preparation approaches reported in the literature for the determination of CECs in environmental samples is provided. Particularly, analytical methodologies involving microextraction approaches used for the enrichment of CECs are discussed. Both solid phase- and liquid phase-based microextraction techniques are highlighted devoting special attention to recently reported approaches. Special emphasis is placed on newly developed materials used for extraction purposes in microextraction techniques. In addition, recent contributions involving miniaturized analytical flow techniques for the determination of CECs are discussed. Besides, the strengths, weaknesses, opportunities and threats of point of need and portable devices have been identified and critically compared with chromatographic methods coupled to mass chromatography. Finally, challenging aspects regarding miniaturized analytical methods for determination of CECs are critically discussed.

Development of an analytical methodology based on fabric phase sorptive extraction followed by gas chromatography-tandem mass spectrometry to determine UV filters in environmental and recreational waters

A novel method based on fabric phase sorptive extraction (FPSE) followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) has been validated for the simultaneous determination of 11 UV filters (ethylhexyl salicylate, benzyl salicylate, homosalate, benzophenone-3, isoamylmethoxycinnamate, 4-methylbenzylidenecamphor, methyl anthranilate, etocrylene, 2-ethylhexylmethoxycinnamate, 2-ethylhexyl p-dimethylaminobenzoate, and octocrylene), in natural and recreational waters. Major experimental parameters affecting FPSE procedure have been optimized to obtain the highest extraction efficiency. Different types and sizes of sol-gel coated FPSE media, sample volume, extraction time, and type and volume of desorption solvent were evaluated. The optimal conditions involved the use of a (2.0 × 2.5) cm² FPSE device with PDMS based coating for the extraction of 20 mL of water for 20 min. The quantitative desorption of the target compounds was performed with 0.5-1 mL of ethyl acetate. The method was satisfactorily validated in terms of linearity, precision, repeatability and reproducibility. Recovery studies were performed at different concentration levels in real water matrices to show its suitability, obtaining mean values about 90% and satisfactory precision. LODs were at the low ng L^-1 in all cases. Finally, the validated FPSE-GC-MS/MS method was applied to different real samples, including environmental water (lake, river, seawater) and recreational water (swimming-pool), where 8 out of the 11 studied compounds were detected at concentrations between 0.12-123 μg L^-1. FPSE is proposed as an efficient and simple alternative to other extraction and microextraction techniques for the analysis of UV filters in waters. Since no matrix effects were observed, quantification could be carried out by conventional calibration with standard solutions, without the need to perform the complete FPSE procedure, thus allowing a higher throughput in comparison with other microextraction techniques.

Investigations on the uptake and transformation of sunscreen ingredients in duckweed (Lemna gibba) and Cyperus alternifolius using high-performance liquid chromatography drift-tube ion-mobility quadrupole time-of-flight mass spectrometry

The uptake, translocation and transformation of three UV-blockers commonly employed in sunscreens, namely avobenzone, octocrylene and octisalate from water by Lemna gibba and Cyperus alternifolius was investigated. Reversed phase high performance liquid chromatography coupled to drift-tube ion-mobility quadrupole time-of-flight mass spectrometry was used for analyzing the extracts from the selected plants after incubation with the UV-blockers for one week. For avobenzone several transformation products resulting from hydroxylation, demethylation and oxidation of the parent molecule could be identified by measuring accurate mass, performing MS/MS experiments and by determining their drift-tube collision cross sections employing nitrogen as drift gas. In addition, the plants were subjected to two commercially available sunscreens, providing similar results to those obtained for the standard solutions of the UV-blockers. Finally, a kinetic study on the uptake and transformation of avobenzone, octocrylene and octisalate was conducted over a period of 216 h, revealing that the UV-filters were mostly present in their parent form and only to a smaller part converted into transformation products.

Vacuum-assisted sorbent extraction: An analytical methodology for the determination of ultraviolet filters in environmental samples

Vacuum-assisted sorbent extraction (VASE) has been applied in combination with gas chromatography-mass spectrometry for the determination of UV filters in water samples. VASE is a variant of headspace extraction which was developed in conjunction with the sorbent pen (SP) technology. This technique combines the advantages of both stir-bar assisted extraction and headspace solid-phase microextraction. The SP traps allowed both reduced pressure in-vial extraction and direct thermal desorption via a unique gas chromatographic injection port. The main parameters that affect the performance of VASE, including both extraction and desorption conditions, were extensively optimized. Under optimum conditions, extraction required 10 mL of sample within 40 mL vials, pH 3.5, ~30 s of air-evacuation, 14 h incubation at 70 °C, stirring at 200 rpm, and a final water management step conducted at ~ -17 °C for 15 min. Optimal thermal desorption required preheating at 260 °C for 2 min followed by desorption at 300 °C for 2 min. The beneficial effect of reduced-pressure extraction was demonstrated by comparing the UV filter extraction time profiles collected using VASE to an analogous atmospheric pressure procedure, resulting in up to a 3-fold improvement under optimized conditions. The VASE methodology enabled simultaneous extractions using different SPs without compromising the method reproducibility, which increases the overall sample throughput. The method was characterized by low limits of detection, from 0.5 to 80 ng L^-1, and adequate reproducibility, with inter-SP and inter-day relative standard deviation lower than 14%. Tap and lake water was successfully analyzed with the proposed methodology, resulting in relative recoveries of spiked samples ranging between 70.0 and 120%.

In situ generation of hydrophobic magnetic ionic liquids in stir bar dispersive liquid-liquid microextraction coupled with headspace gas chromatography

For the first time, an in situ stir bar dispersive liquid-liquid microextraction approach has been developed and coupled with headspace gas chromatography-mass spectrometry for the determination of a group of organic pollutants. The method exploits a new generation of magnetic ionic liquids (MILs) that contain paramagnetic cations based on Ni²⁺ or Co²⁺ metal centers coordinated with either N-butylimidazole or N-octylimidazole ligands and chloride anions. The reactants are added to an aqueous solution containing a high field neodymium rod magnet, followed by the addition of the bis[(trifluoromethyl)sulfonyl]imide anion that promotes a metathesis reaction for the in situ generation of a hydrophobic MIL. Concurrently, a high stirring rate is maintained to exceed the magnetic field of the rod magnet and disperse the generated MIL in the sample solution. When stirring is stopped, the MIL coats the rod magnet due to its paramagnetic nature, facilitating the MIL transfer and subsequent desorption and analysis. Under optimum conditions, the method required a 2.5-18% (w/v) aqueous solution of sodium chloride, 10 mL of sample, 20 or 30 mg of MIL, the addition of a small volume of dispersive solvent, and stirring for 5-7.5 min, depending on the MIL. The method provided limits of detection (LODs) down to 10 μg L^-1, adequate reproducibility (with relative standard deviation values lower than 10% for a spiked level of 80 μg L^-1), and relative recoveries between 72.5% and 102%. Furthermore, the method was successfully applied in the analysis of tap and mineral water.

In situ formation of hydrophobic magnetic ionic liquids for dispersive liquid-liquid microextraction

A new class of magnetic ionic liquid (MIL) containing paramagnetic cations has been applied for in situ dispersive liquid-liquid microextraction in the determination of both polar and non-polar pollutants, including ultraviolet filters, polycyclic aromatic hydrocarbons, alkylphenols, a plasticizer and a preservative in aqueous samples. The MILs were based on cations containing Ni(II) metal centers coordinated with four N-alkylimidazole ligands and chloride anions. The MILs were capable of undergoing in situ metathesis reaction with the bis[(trifluoromethyl)sulfonyl]imide ([NTf₂^-]) anion during the microextraction procedure, generating a water-immiscible extraction solvent containing the preconcentrated analytes. The MIL was then isolated by magnetic separation, followed by direct analysis using reversed-phase high performance liquid chromatography with diode array detection. Among all of the studied MILs, those containing the N-butylimidazole and N-benzylimidazole ligands ([Ni(C₄IM)₄²⁺]2[Cl^-] and [Ni(BeIM)₄²⁺]2[Cl^-], respectively) exhibited the best extraction performance. The method under optimum conditions required 5 mL of sample at pH 3, 20 mg of [Ni(C₄IM)₄²⁺]2[Cl^-] or 30 mg of [Ni(BeIM)₄²⁺]2[Cl^-], 300 μL of acetone or acetonitrile as dispersive solvent (depending on the MIL), a 1:2 M ratio of MIL to [NTf₂^-], and 3 min of vortex. The developed method achieved higher extraction efficiency compared to the conventional MIL-dispersive liquid-liquid microextraction mode, with extraction efficiencies of 46.8-88.6% and 65.4-97.0% for the [Ni(C₄IM)₄²⁺]2[Cl^-] and the [Ni(BeIM)₄²⁺]2[Cl^-] MILs (at a spiked level of 81 μg L^-1), respectively, limits of detection down to 5.2 μg L^-1, and inter-day relative standard deviation lower than 16%.