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A new solid-phase microextraction (SPME) fiber coating was prepared by the immobilization of the metal-organic framework (MOF) CIM-80(Al) on nitinol wires by a green in situ growth approach, using an aqueous synthetic approach, and without the need of any additional material to ensure the attachment of the MOF to the nitinol support. The coating was used for the development of headspace (HS) and direct immersion (DI) SPME methods in combination with gas chromatography and mass spectrometry (GC-MS) for the determination of polycyclic aromatic hydrocarbons (PAHs) as model compounds. Both methods were optimized and validated using the MOF-based fiber together with the commercial polydimethylsiloxane (PDMS) fiber. The MOF extraction phase exhibited superior analytical performance for most of the PAHs in HS-SPME mode (and particularly for less volatiles), while the PDMS fiber presented better results in the DI-SPME method. The analytical performance of the MOF sorbent coating in HS- and DI-SPME methods was also evaluated in urine and brewed coffee samples, without requiring any pretreatment step apart from dilution for DI-SPME experiments, thus showing suitability of the novel coatings for the analysis of complex samples. The proposed CIM-80(Al) fiber was efficient and biocompatible (for using a low cytotoxic sorbent and a biocompatible core support), and it also demonstrated stability and robustness, with inter-fiber (and inter-day) relative standard deviation values lower than 19%, and reusability for more than 80 extraction cycles using 280 °C as desorption temperature.

Metal-organic frameworks (MOFs) are attractive materials used as sorbents in analytical microextraction applications for contaminants of emerging concern (CECs) from environmental liquid matrices. The demanding specs for a sorbent in the analytical application can be comprehensively studied by considering the interactions of the target analytes with the frameworks by the use of single-crystal X-ray diffraction, computational analysis, and adsorption studies, including the kinetic ones. The current study intends a better understanding of the interactions of target CECs (particularly, propylparaben (PPB) as a model) and three Zn-based layered pillared MOFs: CIM-81 [Zn2(tz)2(bdc)] (Htz = 1,2,4-triazole and H2bdc = 1,4-benzenedicarboxylic acid) and their amino derivatives [Zn2(NH2-tz)2(bdc)] CIM-82 and [Zn2(tz)2(NH2-bdc)] CIM-83 (NH2-Htz = 3-amino-1,2,4-triazole and NH2-H2bdc = 2-amino-1,4-benzenedicarboxylic acid). The crystal structures of the two solvate compounds (dma@CIM-81 (dma = dimethylacetamide) and acetone@CIM-81) were solved by single-crystal X-ray diffraction to determine the points of interaction between the framework and the guest molecules. They also served as a starting point for the computational modeling of the PPB@CIM-81 compound, showing that up to two PPB molecules can be hosted in one of the pores, while only one can be trapped in the second pore type, leading to a maximum theoretical capacity of 291.9 mg g-1. This value is close to the value obtained by the adsorption isotherm experiment for CIM-81 (283 mg g-1). This value is, by far, higher than those previously reported for other materials for the removal of PPB from water, and also higher than the experimental values obtained for CIM-82 (54 mg g-1) and CIM-83 (153 mg g-1). The kinetics of adsorption is not very fast, with uptake of about 40% in 3 h, although a 70% release in methanol is achieved in 1 h. In addition, a further comparison of performance in analytical microextraction (requiring only 10 mg of CIM-81) was carried out together with chromatographic analysis to support all insights attained, with the method being able to monitor CECs as low as μg L-1 levels in complex environmental water samples, thus performing successfully for water monitoring even in multicomponent scenarios.

Two ILs containing guanidinium cations (butylguanidinium chloride –C4Gu-Cl– and hexylguanidinium chloride –C6Gu-Cl–) were synthesized and characterized. Their cytotoxicity was also assessed, obtaining adequate CC50 values of 680 ± 99 mg·L−1 for C4Gu-Cl and 135 ± 8 mg·L−1 for C6Gu-Cl. Miniaturized aqueous biphasic systems (μ-ABSs) were developed using amounts lower than 1% (w/w) of these synthesized guanidinium-based ILs, K3PO4 as salting-out agent, and ultrapure water. The phases diagrams of both systems were determined, and the C4Gu-Cl-based μ-ABS was selected for the development of a microextraction method in combination with high performance liquid chromatography (HPLC) with fluorescence detection (FD) for the determination of five polycyclic aromatic hydrocarbons (PAHs) as model analytes. A point of the biphasic region of the C4Gu-Cl-based μ-ABS corresponding to a mixture of 0.75% (w/w) of the IL, 37.7% (w/w) of K3PO4 and 61.55% (w/w) of ultrapure water, and 30 min of equilibrium time, were selected as optimum conditions to obtain high enrichment factors and proper analytical microextraction performance. The C4Gu-Cl-based μ-ABS-HPLC-FD method exhibited low limits of detection, between 0.010 ng·L−1 and 2.0 ng·L−1, average relative recoveries of 96.7%, high enrichment factors ranging from 44.1 to 60.4, average extraction efficiencies of 61.7%, and intermediate precision relative standard deviations lower than 17% for a concentration level of 12 ng·L−1. The developed method was applied successfully in the analysis of different tap water samples.

International audience; New adjuvant formulations, based on proteoliposomes b40 nm and cochleates b100 nm, without Al(OH)3 adjuvant, were evaluated regarding their ability to generate Th1 immune response through a Delayed -Type Hypersensitivity Test, at the mouse model, by using a Neisseria meningitidis B protein complex as antigen. The formulations were administered by intramuscular (IM) (2 inoculations - at baseline and after 14 days) and intranasal (IN) (3 inoculations at 7 days) immunization pathways. All IM immunized groups were able to induce similar response to these formulations as well as to VA-MENGOC-BC® vaccine - containing Al(OH)3 adjuvant (used as positive control of the trial). In all groups, the induced inflammation (IP) rate was statistically higher than in the negative control group (CN) (p b 0.05). Immunogenicity, measured by HSR and CD4+ lymphocyte increase was equivalent to the control vaccine and most important, granuloma reactogenicity at the site of injection was eliminated, fact demonstrated by histological study. All groups of animals immunized by IN route showed HSR reactions and statistically significant differences with respect to the CN group. However, IP values were lower, with statistical differences (p b 0.05) for the same adjuvant formulation IM administered, except the AIF2-nCh formulation that generated statistically similar induction (p N 0.05) by both immunization pathways, suggesting it to be the best candidate for the next IN trial. Proteoliposome and cochleate formulations tested were able to mount potent Th-1 immune response, equivalent to the original vaccine formulation, with the advantage of less reactogenicity in the site of the injection, caused by the toxicity of Al(OH)3 adjuvant gel.

A miniaturized extraction/preconcentration method based on an aqueous biphasic system (mu-ABS) was developed with reagents commonly used as food additives: cholinium chloride (ChCl) as main extraction phase, K2HPO4 as salting-out agent, and water as the main component (being the sample for analyses). With the aim of obtaining high enrichment factors, miniaturization, and adequate analytical performance, a point in the biphasic region with the lowest amount of ChCl was selected, corresponding to 1.55% (w/w) of ChCl, 59.5% (w/w) of K2HPO4, and 38.95% (w/w) of water. The green mu-ABS (attending to its main elements and performance mode) was used in combination with high-performance liquid chromatography with diode-array detection (HPLC-DAD) for the determination of 9 personal care products in wastewater samples. The mu-ABS-HPLC-DAD method showed high enrichment factors (up to 100), and quantitative extraction efficiencies for those compounds containing OH groups in their structure, which can undergo hydrogen bonding with ChCl. Thus, limits of quantification down to 0.8 mu g.L-1 and extraction efficiencies between 66.4 and 108% (concentration levels of 1.3 and 13 mu g.L-1) were reached for the group of parabens and the UV-filter benzophenone-3. The method is characterized by the use of non-harmful reagents and the absence of organic solvents in the entire sample preparation procedure, while being simple, low-cost, easily compatible with HPLC, and highly efficient. (C) 2021 The Author(s). Published by Elsevier B.V. Byla vyvinuta miniaturizovaná extrakční/prekoncentrační metoda založená na vodném dvoufázovém systému (mu-ABS) s činidly běžně používanými jako potravinářské přísady: chlorid cholinitý (ChCl) jako hlavní extrakční fáze, K2HPO4 jako solící činidlo a voda jako hlavní složka (vzorek pro analýzy). S cílem získat vysoké faktory obohacení, miniaturizaci a odpovídající analytický výkon byl vybrán bod v bifázické oblasti s nejnižším množstvím ChCl, což odpovídá 1,55 % (w/w) ChCl, 59,5 % (w/w) K2HPO4 a 38,95 % (w/w) vody. Zelený mu-ABS (s ohledem na jeho hlavní prvky a režim výkonu) byl použit v kombinaci s vysokoúčinnou kapalinovou chromatografií s detekcí diodovým polem (HPLC-DAD) pro stanovení 9 produktů osobní hygieny ve vzorcích odpadních vod. Metoda mu-ABS-HPLC-DAD prokázala vysoké faktory obohacení (až 100) a kvantitativní účinnost extrakce pro ty sloučeniny, které ve své struktuře obsahují OH skupiny, jež mohou podléhat vodíkové vazbě s ChCl. Pro skupinu parabenů a benzofenon-3 s UV filtrem tak bylo dosaženo mezí kvantifikace až do 0,8 mu g.l-1 a extrakčních účinností mezi 66,4 a 108 % (koncentrační hladiny 1,3 a 13 mu g.l-1). Metoda se vyznačuje použitím nezávadných činidel a absencí organických rozpouštědel v celém postupu přípravy vzorku, přičemž je jednoduchá, levná, snadno kompatibilní s HPLC a vysoce účinná.

Aqueous solutions of ionic liquids (ILs) with surface active properties were used as extraction solvents, taking advantage of their impressive solvation properties, in a green microwave-assisted solid-liquid extraction method (IL-MA-SLE) for the extraction of flavonoids from passion fruit and mango leaves. The extraction method was combined with high-performance liquid chromatography and photodiode-array detection (HPLC-PDA) and optimized by response surface methodology using the Box-Behnken experimental design. Under optimum conditions, the extraction efficiency of six structurally different IL-based surfactants was evaluated. Thus, imidazolium-, guanidinium- and pyridinium-type ILs with different tailorable characteristics, such as side chain length and multicationic core, were assessed. The decylguanidinium chloride ([C10Gu+][Cl&ndash, ]) IL-based surfactant was selected as key material given its superior performance and its low cytotoxicity, for the determination of flavonoids of several samples of Passiflora sp. and Mangifera sp. leaves from the Canary Islands, and using as target analytes: rutin, quercetin and apigenin. The analysis of 50 mg of plant material only required 525 &micro, L of the low cytotoxic IL-based surfactant solution at 930 mM, 10.5 min of microwave irradiation at 30 &deg, C and 50 W, which involves a simpler, faster, more efficient and greener method in comparison with other strategies reported in the literature for obtaining bioactive compounds profiles from plants.

This review overviews the main developments achieved in analytical sample preparation regarding the use of solid sorbents as extractants in different sorbent-based miniaturized, micro-scale and microextraction methods. Two main groups are proposed for the classification of the current approaches, based on their operational mode: micro-solid-phase extraction (µ-SPE) and solid-phase microextraction (SPME), while describing their respective main sub-modes: static- and dispersive-µ-SPE, and SPME with fibers and in tube SPME. Furthermore, other important sorbent-based microscale approaches (e.g., stir bar sorptive extraction, stir cake sorptive extraction, stir bar sorptive-dispersive microextraction, and thin film microextraction, among others) are also considered., MJT-R thanks Spanish Ministry of Science and Innovation, for her Juan de la Cierva – formación contract and Aragon Regional Government and the European Social Fund (E07_20R). IP-F thanks the Canary Agency of Research and Innovation (ACIISI), co-funded by the European Social Fund, for her FPI PhD fellowship. VP thanks the Spanish Ministry of Economy and Competitiveness (MINECO) for the project MAT2017-89207-R.

A novel ionic liquid (IL)-based microextraction method has been developed for the determination of four hydroxylated polycyclic aromatic hydrocarbons (OHPAHs) in urine samples. The water soluble IL-based surfactant selected as extraction solvent is decylguanidinium chloride (C10Gu-Cl), the cytotoxicity and micellar behavior of which were evaluated. The proposed salt-induced IL-based preconcentration method simply consists in adding NaClO4 to the aqueous medium containing the IL to promote its water insolubility. The entire method was optimized, requiring the use of only 20 μL of C10Gu-Cl for 10 mL of diluted urine sample (1:10) without any pH adjustment, followed by the addition of NaClO4 to ensure a 5% (w/v) content. A cloudy solution was observed immediately, and after the application of 4 min of vortex and 8 min of centrifugation, the droplet was diluted up to 60 μL with a mixture of acetonitrile:water (30:70) and injected into the liquid chromatograph with fluorescence detection. The method was validated using both synthetic urine and human urine as matrix for the determination of the four OHPAHs. The following analytical features were obtained: detection limits down to 1 ng·L-1 in real urine; inter-day reproducibility (as RSD in %) always lower than 17% when dealing with real urine samples spiked at 80 ng·L-1; and average relative recoveries of 102% in real urine samples at such low spiked levels. Despite the simplicity of the proposed method, it performed successfully with complex urine samples.

An in situ dispersive liquid–liquid microextraction (DLLME) method together with flame atomic absorption spectroscopy (FAAS) is developed for the extraction and determination of copper and cadmium from aqueous samples using as an extraction solvent a low cytotoxic ionic liquid (IL)-based surfactant, specifically decylguanidinium chloride (C10Gu-Cl). The IL-based surfactant 1-hexadecyl-3-butylimidazolium bromide (C16C4Im-Br) is also used for comparative purposes. In the method, N,N′-bis(salicylidene)thiocarbohydrazide is the complexing agent, and the metathesis reaction in the in situ DLLME is accomplished using lithium bis[(trifluoromethyl)sulfonyl]imide. The main parameters affecting the extraction efficiency of the method, i.e. pH of the sample, NaCl content, and vortex time, are properly optimized with a Doehlert experimental design. The method using C10Gu-Cl exhibited a limit of detection (LOD) four times lower and with slightly better reproducibility than that of the imidazolium IL-based surfactant. The validation of the in situ DLLME-FAAS method with C10Gu-Cl is accomplished for the simultaneous extraction and quantification of copper and cadmium from water. The optimum method requires 10 mL of aqueous sample and ∼25 μL of the IL-based surfactant to obtain a microdroplet of ∼21 μL, which is diluted up to 120 μL with acetonitrile to perform the analytical determination of both metals. LODs down to 0.3 and 0.5 μg L−1 were reached with the entire in situ IL-DLLME-FAAS for copper and cadmium, respectively. The inter-day relative standard deviation values were lower than 17% for both metal ions; with relative recoveries of 97.8% and 102%, and enrichment factors of 85 and 94, for copper and cadmium, respectively, at a low spiked level (4 and 6 μg L−1, respectively). Furthermore, the developed method shows adequate precision and accuracy evaluated with a certified reference material, the absence of matrix effects, and high tolerance limits towards common cations (between 80 and 600) for the analysis of tap water, while accomplishing the requirements of green analytical chemistry.

A headspace solid-phase microextraction (HS-SPME) method was developed using the metal-organic framework (MOF) CIM-80(Al) as extraction phase and in combination with gas chromatography-mass spectrometry (GC-MS) for the simultaneous determination of 6 methylsiloxanes and 7 musk fragrances in different environmental waters. The chromatographic separation was optimized in different GC instruments equipped with different detectors, allowing the correct separation and identification of the compounds. The HS-SPME method was optimized using a Box-Behnken experimental design, while the validation was carried out together with the most suitable commercial fiber (divinylbenzene/polydimethylsiloxane) for comparison purposes. The MOF-based coating was particularly efficient for the determination of volatile methylsiloxanes, showing moderately lower limits of detection (of 0.2 and 0.5 μg·L-1 versus 0.6 μg·L-1 for cyclic methylsiloxanes) and slightly better precision (relative standard deviation values lower than 17% versus 22%) than the commercial coating, while avoiding the cross-contamination issues associated to the polymeric composition of commercial fibers. The method was applied for the analysis of seawater and wastewater samples, allowing the quantification of several analytes and the assessment of matrix effects. The proposed HS-SPME method using the CIM-80(Al) fiber constitutes a more environmentally friendly, simpler, and efficient strategy in comparison with other sample preparation methods using different extraction techniques, while the use of a MOF as fiber sorbent constitutes a potential alternative to exploit the features of SPME for the challenging environmental monitoring of these compounds.

The utilization of agro-industrial byproducts into the diets of dairy goats is an alternative feeding covered in this study. The differences between the physicochemical and sensory characteristics were obtained for Canary Islands cheeses made with raw milk of goats fed with a control diet (CD) or with a banana silage-based diet (BD), and ripened at different times. Banana silage-based diets were: BD1 with ∼10% of banana packaging residues silage; and BD2 with ∼20%. The incorporation of BD to the diets leads to cheeses without significant modifications of their physicochemical properties while keeping flavour and odour attributes typical of Canary cheeses, and without flavour defects. The inclusion of banana silage in the diets clearly implies the detection of citric and fermented fruit odours, which are not present in CD cheeses. Cluster analysis, principal component analysis, and lineal discriminant analysis, were used to evaluate differences on the studied parameters of the cheeses.

A pH-sensitive polymer based on the poly(styrene- alt -maleic anhydride) co-polymer serves as basis to develop a microextraction method (pH-HGME) in direct combination with high-performance liquid chromatography (HPLC) and fluorescence detection (FD) for the determination of seven organic com- pounds, including three polycyclic aromatic hydrocarbons (PAHs), three monohydroxylated PAHs and one alkylphenol, in urine. The method bases on the structural modification of the pH-sensitive polymer in the aqueous sample at a high pH value, followed by the formation and insolubilization of a hydrogel contain- ing the preconcentrated analytes by decreasing the pH, and the direct injection of the hydrogel-rich phase in the HPLC-FD system. The optimization of the main variables permitted the selection of low amounts of aqueous sample (10 mL), which was mixed with 10 mg of co-polymer also present in a low volume (150 μL) of concentrated NaOH. The method further requires the addition of 200 μL of concentrated HCl, 3 min of stirring, and 15 min of centrifugation. This pH-HGME-HPLC-FD method presented low limits of detection, ranging from 0.001 μg L −1 to 0.09 μg L −1 in ultrapure water, average relative recoveries of 96.9% for the concentration level of 0.60 μg L −1 , and enrichment factors between 1.50 and 17.7. The pro- posed method also exhibited high precision, with intermediate relative standard deviations lower than 16% for a concentration level of 0.60 μg L −1 . The developed pH-HGME-HPLC-FD method performed ade- quately when analyzing two human urine samples provided by a non-smoker male and a smoker female, respectively. One of the target analytes (2-hydroxynaphthalene) was quantified in both samples using the standard addition method, with a predicted concentration of 7.3 ±0.4 μg L −1 in the non-smoker male urine and 19.3 ±0.6 μg L −1 in the smoker female urine. Agencia Canaria de Investigación, Innovación y Sociedad de la Información University of Regensburg Ministerio de Ciencia, Innovación y Universidades Ministerio de Economía, Industria y Competitividad

The mixed-ligand strategy was selected as an approach to tailor a metal&ndash, organic framework (MOF) with microextraction purposes. The strategy led to the synthesis of up to twelve UiO-66-based MOFs with different amounts of functionalized terephthalate ligands (H-bdc), including nitro (-NO2) and amino (-NH2) groups (NO2-bdc and NH2-bdc, respectively). Increases of 25% in ligands were used in each case, and different pore environments were thus obtained in the resulting crystals. Characterization of MOFs includes powder X-ray diffraction, infrared spectroscopy, and elemental analysis. The obtained MOFs with different degrees and natures of functionalization were tested as sorbents in a dispersive miniaturized solid-phase extraction (D-&micro, SPE) method in combination with high-performance liquid chromatography (HPLC) and diode array detection (DAD), to evaluate the influence of mixed functionalization of the MOF on the analytical performance of the entire microextraction method. Eight organic pollutants of different natures were studied, using a concentration level of 5 &micro, g&middot, L&minus, 1 to mimic contaminated waters. Target pollutants included carbamazepine, 4-cumylphenol, benzophenone-3, 4-tert-octylphenol, 4-octylphenol, chrysene, indeno(1,2,3-cd)pyrene, and triclosan, as representatives of drugs, phenols, polycyclic aromatic hydrocarbons, and disinfectants. Structurally, they differ in size and some of them present polar groups able to form H-bond interactions, either as donors (-NH2) or acceptors (-NO2), permitting us to evaluate possible interactions between MOF pore functionalities and analytes&rsquo, groups. As a result, extraction efficiencies can reach values of up to 60%, despite employing a microextraction approach, with four main trends of behavior being observed, depending on the analyte and the MOF.

Several crosslinked polymeric ionic liquid (PIL)-based sorbent coatings of different nature were prepared by UV polymerization onto nitinol wires. They were evaluated in a direct-immersion solid-phase microextraction (DI-SPME) method in combination with high-performance liquid chromatography (HPLC) and diode array detection (DAD). The studied PIL coatings contained either vinyl alkyl or vinylbenzyl imidazolium-based (ViCnIm- or ViBCnIm-) IL monomers with different anions, as well as different dicationic IL crosslinkers. The analytical performance of these PIL-based SPME coatings was firstly evaluated for the extraction of a group of 10 different model analytes, including hydrocarbons and phenols, while exhaustively comparing the performance with commercial SPME fibers such as polydimethylsyloxane (PDMS), polyacrylate (PA) and polydimethylsiloxane/divinylbenzene (PDMS/DVB), and using all fibers under optimized conditions. Those fibers exhibiting a high selectivity for polar compounds were selected to carry out an analytical method for a group of 5 alkylphenols, including bisphenol-A (BPA) and nonylphenol (n-NP). Under optimum conditions, average relative recoveries of 108% and inter-day precision values (3 non-consecutive days) lower than 19% were obtained for a spiked level of 10 µg L−1. Correlations coefficients for the overall method ranged between 0.990 and 0.999, and limits of detection were down to 1 µg L−1. Tap water, river water, and bottled water were analyzed to evaluate matrix effects. Comparison with the PA fiber was also performed in terms of analytical performance. Partition coefficients (log Kfs) of the alkylphenols to the SPME coating varied from 1.69 to 2.45 for the most efficient PIL-based fiber, and from 1.58 to 2.30 for the PA fiber. These results agree with those obtained by the normalized calibration slopes, pointing out the affinity of these PILs-based coatings.

A hybrid material composed by the metal-organic framework (MOF) HKUST-1 and Fe3O4 magnetic nanoparticles (MNPs) has been synthetized in a quite simple manner, characterized, and used in a magnetic-assisted dispersive micro-solid-phase extraction (M-d-μSPE) method in combination with ultra-high-performance liquid chromatography (UHPLC) and fluorescence detection (FD). The application was devoted to the determination of 8 heavy polycyclic aromatic hydrocarbons (PAHs) in different aqueous samples, specifically tap water, wastewaters, and fruit tea infusion samples. The overall M-d-μSPE-UHPLC-FD method was optimized and validated. The method is characterized by: its simplicity in both the preparation of the hybrid material (simple mixing) and the magnetic-assisted approach (∼10min extraction time), the use of low sorbent amounts (20mg of HKUST-1 and 5mg of Fe3O4 MNPs), and the low organic solvent consumption in the overall M-d-μSPE-UHPLC-FD method (1.5mL of acetonitrile in the M-d-μSPE method and 2.8mL of acetonitrile in the UHPLC-FD run). The resulting method has high sensitivity, with LODs down to 0.8ngL(-1); adequate intermediate precision, with relative standard deviation values (RSD) always lower than 6.3% (being the range 5.9-9.0% in tap water for a spiked level of 45ngL(-1), 6.1-14% in wastewaters for a spiked level of 45ngL(-1), and 7.2-17% in fruit tea infusion samples for a spiked level of 45ngL(-1)); and adequate relative recoveries, with average values of 82% in tap water, and 94% and 75% in wastewater and fruit tea infusion samples, respectively, if using the proper matrix-matched calibration.

Chemical vapor deposition of MOFs (MOF-CVD) has been used to coat solid-phase microextraction (SPME) fibers with ZIF-8, by exposing ZnO layers to the linker vapor (2-methylimidazole). This ZIF-8 coating has been used as a seed layer in a following solvothermal MOF growth step in order to increase the ZIF-8 thickness. The combined MOF-CVD and solvothermal growth of ZIF-8 on the fibers result in a thickness of ~3 μm, with adequate thermal stability, and mechanical integrity when tested with methanol and acetonitrile ultrasonic treatments. The fibers have been evaluated in direct immersion mode using gas chromatography and flame ionization detection (GC-FID), for a group of target analytes including three polycyclic aromatic hydrocarbons (PAHs) and five personal care products (PCPs). The optimized conditions of the SPME-GC-FID methods include low amount of aqueous sample (5 mL), stirring for 45 min at 35 °C, and desorption at 280 °C for 5 min. The method presents limits of detection down to 0.6 μg L−1; intra-day, inter-day and inter-batch relative standard deviation values lower than 16%, 19%, and 23%, respectively; and a lifetime higher than 70 cycles.

The pillared-layer Zn-triazolate metal-organic framework (CIM-81) was synthesized, characterized, and used for the first time as a sorbent in a dispersive micro-solid phase extraction method. The method involves the determination of a variety of personal care products in wastewaters, including four preservatives, four UV-filters, and one disinfectant, in combination with ultra-high performance liquid chromatography and UV detection. The CIM-81 MOF, constructed with an interesting mixed-ligand synthetic strategy, demonstrated a better extraction performance than other widely used MOFs in D-&micro, SPE such as UiO-66, HKUST-1, and MIL-53(Al). The optimization of the method included a screening design followed by a Doehlert design. Optimum conditions required 10 mg of CIM-81 MOF in 10 mL of the aqueous sample at a pH of 5, 1 min of agitation by vortex and 3 min of centrifugation in the extraction step, and 1.2 mL of methanol and 4 min of vortex in the desorption step, followed by filtration, evaporation and reconstitution with 100 &micro, L of the initial chromatographic mobile phase. The entire D-&micro, SPE-UHPLC-UV method presented limits of detection down to 0.5 ng&middot, mL&minus, 1, intra-day and inter-day precision values for the lowest concentration level (15 ng&middot, 1)-as a relative standard deviation (in %)-lower than 8.7 and 13%, respectively, average relative recovery values of 115%, and enrichment factors ranging from ~3.6 to ~34. The reuse of the CIM-81 material was assessed not only in terms of maintaining the analytical performance but also in terms of its crystalline stability.

Four metal-organic frameworks (MOFs), specifically UiO-66, UiO-66-NH2, UiO-66-NO2, and MIL-53(Al), were synthesized, characterized, and used as sorbents in a dispersive micro-solid phase extraction (D-&micro, SPE) method for the determination of nine pollutants of different nature, including drugs, phenols, polycyclic aromatic hydrocarbons, and personal care products in environmental waters. The D-&micro, SPE method, using these MOFs as sorbents and in combination with high-performance liquid chromatography (HPLC) and diode-array detection (DAD), was optimized. The optimization study pointed out to UiO-66-NO2 as the best MOF to use in the multi-component determination. Furthermore, the utilization of isoreticular MOFs based on UiO-66 with the same topology but different functional groups, and MIL-53(Al) to compare with, allowed us for the first time to evaluate the influence of such functionalization of the ligand with regards to the efficiency of the D-&micro, SPE-HPLC-DAD method. Optimum conditions included: 20 mg of UiO-66-NO2 MOF in 20 mL of the aqueous sample, 3 min of agitation by vortex and 5 min of centrifugation, followed by the use of only 500 &micro, L of acetonitrile as desorption solvent (once the MOF containing analytes was separated), 5 min of vortex and 5 min of centrifugation. The validation of the D-&micro, SPE-HPLC-DAD method showed limits of detection down to 1.5 ng&middot, L&minus, 1, average relative recoveries of 107% for a spiked level of 1.50 &micro, g&middot, 1, and inter-day precision values with relative standard deviations lower than 14%, for the group of pollutants considered.

The CIM-80 material (aluminum(III)-mesaconate) has been synthetized in high yield through a novel green procedure involving water and urea as co-reactants. The CIM-80 material exhibits good thermal stability with a working range from RT to 350 °C with a small contraction upon desolvation. Moreover, this material is stable in water at different pH values (1–10) for at least one week, and shows a LC50 value higher than 2 mg mL−1. The new material has been tested in a microextraction methodology for the monitoring of up to 22 water pollutants while presenting little environmental impact: only 20 mg of CIM-80 and 500 μL of acetonitrile are needed per analysis. The analytical performance of the CIM-80 in the microextraction strategy is similar to or even better for several pollutants than that of MIL-53(Al). The average extraction efficiencies range from ∼20% for heavy polycyclic aromatic hydrocarbons to ∼70–100% for the lighter ones. In the case of the emerging contaminants, the average extraction efficiency can reach values up to 70% for triclosan and carbamazepine.

A vortex-assisted emulsification microextraction (VAEME) procedure has been evaluated for the determination of ten personal care products (PCPs), including seven preservatives (parabens), two UV filters (benzophenones), and one disinfectant (triclosan), in environmental waters. The method is utilized in combination with ultra-high performance liquid chromatography (UHPLC) and UV detection. The results obtained from the liquid-phase microextraction method are reasonably simple because the method only needs one extractant (200 μL of trichloromethane under optimum conditions) and it completely avoids the use of any dispersive solvent or surfactants to help the emulsification. The optimized method ensures the correct emulsification by simple application of 3 min of vortex to 8 mL of aqueous sample at pH 5 containing 15% (w/v) of sodium chloride, followed by centrifugation (5 min at 3500 rpm), droplet sampling using a syringe, droplet solvent evaporation, and reconstitution with 100 μL of a mixture of acetonitrile–water (35 : 65, v/v) before UHPLC injection. The overall extraction time is roughly 10 min, and the chromatographic time ∼12 min. The optimized method was validated and presented average relative recoveries of 112%, average real extraction efficiencies of 82.7%, inter-day precision values with relative standard deviation (RSD, in %, for n = 9) values lower than 10%, and enrichment factors between ∼20 and ∼100, for a spiked level of 3.75 μg L−1. Limits of detection down to 0.03 μg L−1 were also obtained. The method performed well for environmental water samples with different natures and complexities.

Ionic liquid-based surfactants are a group of ionic liquid derivatives capable of forming micellar aggregates when dissolved in water above a certain concentration, known as the critical micelle concentration (CMC). This new class of surfactants was initially obtained by incorporating long alkyl chain substituents within the charged cationic group of conventional monocationic IL structures. More recently, dicationic, tricationic, and functionalized IL-based surfactants have been described. IL-based surfactants present great tuneability as original ILs: simple modifications in their structures produce important variations in their micellar properties. Furthermore, micelles formed by IL-based surfactants exhibit lower CMC values than conventional cationic surfactants when comparing similar structures. It is important to characterize the micellization and interfacial behaviour of IL-based surfactants in order to apply them successfully in specific fields. Several techniques can be used for such characterization, such as surface tension, fluorescence and conductivity measurements. Due to their structural versatility and singular properties, IL-based surfactants have generated a great deal of interest, which is reflected in the increasing number of applications that have been reported in recent years. Among the main applications of IL-based surfactants, worthy of mention are biomedicine, catalysis, solvents, nanotechnology, and separation science fields.

Free fatty acids and sensory profiles were obtained for cheeses made with raw goat milk and vegetable coagulant, derived from the cardoon flower ( Cynara cardunculus), at different ripening times (7 and 20 days). A solid–liquid phase extraction method followed by solid-phase extraction and gas chromatography was used. Profiles were also obtained with cheeses made with commercial coagulant, traditional kid rennet paste, and mixture coagulant (vegetable coagulant-kid rennet). The use of vegetable coagulant and vegetable coagulant-kid rennet is common in traditional Protected Designation of Origin cheeses such as “ Queso Flor de Guía” and “ Queso Media Flor de Guía” (Spain). Contents of short-chain free fatty acids (7.5–22.5 mmol·kg−1), medium-chain free fatty acids (0.4–3.7 mmol·kg−1), and long-chain free fatty acids (0.2–2.1 mmol·kg−1) varied depending on the coagulant type and the ripening time. Vegetable coagulant cheeses present odour intensity and flavour intensity much higher than commercial coagulant cheeses in the sensory analysis for cheeses obtained with seven days of ripening, but the values decrease when increasing the ripening time. Multivariate analysis allowed us to differentiate cheese samples according to the ripening time when using lipolytic profile and according to the coagulant type using the sensory profile.

The IL-based surfactant octylguanidinium chloride (C8Gu-Cl) was designed and synthetized with the purpose of obtaining a less harmful surfactant: containing guanidinium as core cation and a relatively short alkyl chain. Its interfacial and aggregation behavior was evaluated through conductivity and fluorescence measurements, presenting a critical micelle concentration value of 42.5 and 44.6mmolL-1, respectively. Cytotoxicity studies were carried out with C8Gu-Cl and other IL-based and conventional surfactants, specifically the analogue 1-octyl-3-methylimidazolium chloride (C8MIm-Cl), and other imidazolium- (C16MIm-Br) and pyridinium- (C16Py-Cl) based surfactants, together with the conventional cationic CTAB and the conventional anionic SDS. From these studies, C8Gu-Cl was the only one to achieve the classification of low cytotoxicity. An in situ dispersive liquid-liquid microextraction (DLLME) method based on transforming the water-soluble C8Gu-Cl IL-based surfactant into a water-insoluble IL microdroplet via a simple metathesis reaction was then selected as the extraction/preconcentration method for a group of 6 personal care products (PCPs) present in cosmetic samples. The method was carried out in combination with high-performance liquid chromatography (HPLC) and diode array detection (DAD). The method was properly optimized, requiring the use of only 30μL of C8Gu-Cl for 10mL of aqueous sample with a NaCl content of 8% (w/v) to adjust the ionic strength and pH value of 5. The metathesis reaction required the addition of the anion exchange reagent (bis[(trifluoromethyl)sulfonyl]imide - 1:1 molar ratio), followed by vortex and centrifugation, and dilution of the final microdroplet up to 60μL with acetonitrile before the injection in the HPLC-DAD system. The optimum in situ DLLME-HPLC-DAD method takes ∼10min for the extraction step and ∼22min for the chromatographic separation, with analytical features of low detection limits: down to 0.4μgL-1; high reproducibility: with RSD values lower than 10% (intra-day) and 16% (inter-day) for a spiked level of 15μgL-1; and an average enrichment factor of 89. The requirement of low volumes (30μL) of a low cytotoxic IL-based surfactant allows the method to be considered less harmful than other common analytical microextraction approaches.

We have evaluated a vortex-assisted emulsification microextraction (VAEME) procedure followed by in-syringe ultrasound-assisted back-microextraction for the determination of nine haloacetic acids in waters of different nature, using high-performance liquid chromatography with diode array detection. The optimized method requires 600 μL of isopropyl ether as an extractant solvent and 5 mL of the water sample containing: Na2SO4 (45%, w/v) and a low pH value (

A simple and efficient method has been developed for the extraction and determination of 16 common volatile halogenated disinfection by-products (DBPs) (four trihalomethanes, six haloacetonitriles, and six halonitromethanes) in blending desalinated waters, using headspace solid-phase microextraction and gas chromatography with flame ionization detector (HS-SPME/GC-FID). After the optimization using factorial designs of the HS-SPME parameters (optimum: carboxen/polydimethylsiloxane such as fiber, extraction time of 60 min at 30°C, pH 7, addition of 40% (w/v) of sodium chloride, and desorption time of 2 min at 250°C), quantification limits ranged from 3.03 to 40.8 µg L−1, and relative standard deviation (inter-day) were lower than 9.7% for all the target DBPs. Adequate relative recoveries (with the exception of chloronitromethane) were obtained even when spiking waters at low levels (25 µg L−1), with values between 83.1% and 119% for ultrapure water, and between 87.4% and 115% for blending desalinat...

Summarization: This work proposes a new vacuum headspace solid-phase microextraction (Vac-HSSPME) method combined to gas chromatography-flame ionization detection for the determination of free fatty acids (FFAs) and phenols. All target analytes of the multicomponent solution were volatiles but their low Henry's Law constants rendered them amenable to Vac-HSSPME. The ability of a new and easy to construct Vac-HSSPME sampler to maintain low-pressure conditions for extended sampling times was concurrently demonstrated. Vac-HSSPME and regular HSSPME methods were independently optimized and the results were compared at all times. The performances of four commercial SPME fibers and two polymeric ionic liquid (PIL)-based SPME fibers were evaluated and the best overall results were obtained with the adsorbent-type CAR/PDMS fiber. For the concentrations used here, competitive displacement became more intense for the smaller and more volatile analytes of the multi-component solution when lowering the sampling pressure. The extraction time profiles showed that Vac-HSSPME had a dramatic positive effect on extraction kinetics. The local maxima of adsorbed analytes recorded with Vac-HSSPME occurred faster, but were always lower than that with regular HSSPME due to the faster analyte-loading from the multicomponent solution. Increasing the sampling temperature during Vac-HSSPME reduced the extraction efficiency of smaller analytes due to the enhancement in water molecule collisions with the fiber. This effect was not recorded for the larger phenolic compounds. Based on the optimum values selected, Vac-HSSPME required a shorter extraction time and milder sampling conditions than regular HSSPME: 20 min and 35 °C for Vac-HSSPME versus 40 min and 45 °C for regular HSSPME. The performance of the optimized Vac-HSSPME and regular HSSPME procedures were assessed and Vac-HSSPME method proved to be more sensitive, with lower limits of detection (from 0.14 to 13 μg L−1), and better intra-day precision (relative standard deviations values < 10% at the lowest spiked level) than regular HSSPME for almost all target analytes. The proposed Vac-HSSPME method was successfully applied to quantify FFAs and phenols in milk and milk derivatives samples. Presented on: Analytica Chimica Acta

The environmental monitoring of trihalomethanes (THMs) has been performed by setting up a dispersive liquid-liquid microextraction method in combination with gas chromatography (GC)-mass spectrometry (MS). The optimized method only requires ∼26 µL of decanol as extractant solvent, dissolved in ∼1 mL of acetone (dispersive solvent) for 5 mL of the environmental water containing THMs. The mixture is then subjected to vortex for 1 min and then centrifuged for 2 min at 3500 rpm. The microdroplet containing the extracted THMs is then sampled with a micro-syringe, and injected (1 µL) in the GC-MS. The method is characterized for being fast (3 min for the entire sample preparation step) and environmentally friendly (low amounts of solvents required, being all non-chlorinated), and also for getting average relative recoveries of 90.2-106% in tap waters; relative standard deviation values always lower than 11%; average enrichment factors of 48-49; and detection limits down to 0.7 µg·L-1. Several waters: tap waters, pool waters, and wastewaters were successfully analyzed with the method proposed. Furthermore, the method was used to monitor the formation of THMs in wastewaters when different chlorination parameters, namely temperature and pH, were varied.

This work describes the applicability of magnetic ionic liquids (MILs) in the analytical determination of a group of heavy polycyclic aromatic hydrocarbons. Three different MILs, namely, benzyltrioctylammonium bromotrichloroferrate (III) (MIL A), methoxybenzyltrioctylammonium bromotrichloroferrate (III) (MIL B), and 1,12-di(3-benzylbenzimidazolium) dodecane bis[(trifluoromethyl)sulfonyl)]imide bromotrichloroferrate (III) (MIL C), were designed to exhibit hydrophobic properties, and their performance examined in a microextraction method for hydrophobic analytes. The magnet-assisted approach with these MILs was performed in combination with high performance liquid chromatography and fluorescence detection. The study of the extraction performance showed that MIL A was the most suitable solvent for the extraction of polycyclic aromatic hydrocarbons and under optimum conditions the fast extraction step required ∼20 μL of MIL A for 10 mL of aqueous sample, 24 mmol L(-1) NaOH, high ionic strength content of NaCl (25% (w/v)), 500 μL of acetone as dispersive solvent, and 5 min of vortex. The desorption step required the aid of an external magnetic field with a strong NdFeB magnet (the separation requires few seconds), two back-extraction steps for polycyclic aromatic hydrocarbons retained in the MIL droplet with n-hexane, evaporation and reconstitution with acetonitrile. The overall method presented limits of detection down to 5 ng L(-1), relative recoveries ranging from 91.5 to 119%, and inter-day reproducibility values (expressed as relative standard derivation) lower than 16.4% for a spiked level of 0.4 μg L(-1) (n = 9). The method was also applied for the analysis of real samples, including tap water, wastewater, and tea infusion.

Ionic-liquid-based aqueous biphasic systems (IL-based ABS) combine the advantages of both ionic liquids (ILs) and aqueous biphasic systems (ABS) in extraction approaches. Most ILs are liquid solvents exclusively composed of ions, characterized for low to negligible vapor pressures at ambient conditions, extraordinary chemical and thermal stabilities, and impressive solvation abilities for polar to nonpolar compounds, among many other properties. ABS permit the development of extraction methods without the need of using toxic and volatile organic solvents, while both immiscible phases involved in the extraction procedure are aqueous rich. Thus, the combination of hydrophilic ILs with ABS has implied numerous effective applications for different target compounds. In this chapter, attention is focused on applications of IL-based ABS for the extraction of alcohols, phenols, aromatic dyes, and other aromatic compounds. The discussion is centered on the nature of the IL-based ABS, their characterization, and the performance of the extraction procedure, among other features.

The determination of a group of organic contaminants from marine sediments samples including three polycyclic aromatic hydrocarbons, five alkylphenols ( i.e., bisphenol-A or nonylphenol) and one paraben has been carried out using an extraction/preconcentration strategy with ionic liquid-based surfactants and high-performance liquid chromatography (HPLC) with diode array detection (DAD). Sediments are first extracted using two IL-based surfactants, specifically 1-hexadecyl-3-methyl imidazolium bromide (C 16 MIm–Br) and 1-hexadecyl-3-butyl imidazolium bromide (C 16 C 4 Im–Br), as the extraction media in a microwave-assisted extraction (MAE) procedure, followed by a novel in situ preconcentration method. The optimized MAE method requires 0.1 g of sediment and 5 mL of 40 mM C 16 MIm–Br IL solution. The extracts are then centrifuged and filtered. The subsequent preconcentration in situ approach consists of the insolubilization of an IL-based surfactant formed by a metathesis reaction using the anion-exchange reagent lithium bis[(trifluoromethane)sulfonyl]imide (LiNTf 2 ), which produces an analyte enriched IL microdroplet. The optimized in situ approach utilizes 4 mL of the filtered extract, which are mixed with acetonitrile and 92 μL of LiNTf 2 solution (0.5 g mL −1 ), heated, vortexed and centrifuged. The formed IL microdroplet is then simply diluted with acetonitrile (∼100 μL) and injected in the chromatograph without any further clean-up steps. The overall extraction/preconcentration method requires approximately 25 min in spite of dealing with complex solid samples, is nearly free of organic solvent (requires ∼900 μL of acetonitrile per sample), and produces high preconcentration factors and quantification limits down to 0.04 mg kg −1 using HPLC–DAD.

We have evaluated an in-situ ionic liquid-dispersive liquid-liquid microextraction procedure for the determination of six endocrine disrupting phenols in seawaters and industrial effluents using HPLC. The optimized method requires 38 μL of the water-soluble ionic liquid 1-butyl-3-methylimidazolium chloride, and 5 mL of seawater or industrial effluent. After appropriate work-up, a drop (~10 μL) of an ionic liquid is formed that contains the analytes of interest. It is diluted with acetonitrile and injected into the HPLC system. This procedure is accomplished without heating or cooling the solutions. The method is characterized by (a) average relative recoveries of 90.2%, (b) enrichment factors ranging from 140 to 989, and (c) precisions (expressed as relative standard deviations) of less than 11% when using a spiking level of 10 ng mL−1. The limits of detection range from 0.8 ng mL−1 for 4-cumylphenol to 4.8 ng mL−1 for bisphenol-A.

The effects of several ionic liquids (ILs) as mobile-phase additives in HPLC with fluorescence and UV-Vis detection for the determination of six heterocyclic aromatic amines were evaluated using two different C(18) stationary phases with moderate silanol activity. The studied ILs were 1-butyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium tetrafluoroborate and 1-methyl-3-octylimidazolium tetrafluoroborate. The optical behaviour of heterocyclic aromatic amines in presence of ILs was studied and the silanol-suppressing potency of ILs was evaluated for the two stationary phases studied. Several chromatographic parameters were evaluated in the presence or absence of ILs, or using triethylamine, the most common mobile-phase additive. The best results were achieved using 1 mM 1-butyl-3-methylimidazolium tetrafluoroborate as mobile-phase additive and NovaPak column. In these conditions and with 18% of ACN in the mobile phase, analytical performance of the chromatographic methods using fluorescence and UV-Vis were evaluated, obtaining good precision in all cases (RSD lower than 6.6%) and low LOD (0.001-0.147 microg/mL with UV-Vis and 0.001-0.006 ng/mL with fluorescence detection).

Analytical aspects concerning the heterocyclic aromatic amines (HAAs) determination in foods are reviewed. Sample pre-treatment procedures such as liquid-liquid extraction (LLE), supercritical fluid extraction, solid-phase extraction (SPE), solid-phase microextraction (SPME), and the mainly used LLE-SPE tandem extraction are discussed. The analytical methods used for the identification and quantification are HPLC, HPLC combined with single or tandem MS detection (HPLC-MS, HPLC-MS/MS), GC-MS and capillary electrophoresis. Advantages and figures of merit for each technique are discussed.

A method to extract PAHs from sediments is carried out using aqueous solutions containing aggregates of the ionic liquid (IL) 1-hexadecyl-3-methylimidazolium bromide (HDMIm-Br) as the extracting medium. Focused microwave-assisted extraction has been used to accelerate the extraction step, followed by HPLC with fluorescence detection without clean-up steps to remove the IL prior to injection. The method has been applied to certified reference sediment BCR-535 and marine sediments from Tenerife (Canary Islands) with successful results. The optimized method gave average absolute recoveries of 91.1% for six of the seven PAHs studied, with relative standard deviations lower than 10.4%. The overall method is characterized for presenting low extraction times (6min), low amounts of the sediment (0.1g), low amounts of IL (45mM), and low volumes of aqueous extractant solution (9mL). The use of small amounts of both IL and aqueous extractant solution allows the method to be considered environmental-friendly.

This work describes the estimation of uncertainty following the “bottom‐up” approach for the quantification process of thirteen carbonyl compounds, as 2,4‐dinitrophenylhydrazone derivatives, by high performance liquid chromatography with ultraviolet detection (HPLC‐UV). These results are compared with the ones obtained using gas chromatography‐mass spectrometry (GC‐MS). A study of the linear range was established and validation was performed for both methods using statistical analysis of several indicative parameters. In terms of validation data, precision (RSD

This work describes the estimation of uncertainty following the “bottom‐up” and the “top‐down” approaches for the determination of several trace metals in seawater when using a classical 1‐pyrrolidinedithiocarbamate/diethyldithiocarbamate/freon extraction method followed by electrothermal atomic absorption spectrometry. A detailed analysis of the uncertainty sources of this method is included, which allows estimating the expanded uncertainties. The results show that the main contribution to the relative overall uncertainty is the extraction step. The estimation of the uncertainty components is shown to be a suitable tool for the experimental design in order to obtain a small uncertainty in the analytical result.

A method for the determination of 19 chlorophenols in industrial effluents samples using solid-phase microextraction (SPME) coupled to gas chromatography–mass spectrometry has been developed. Four kinds of different SPME fibres have been studied. Among them, the polyacrylate and carbowax®-divinylbenzene fibres were the most adequate. The extraction process was optimized by means of the experimental design, which allows the study of a large number of factors with a reasonable number of experiments. The optimized method allows the determination of the studied chlorophenols in complex matrices with a high organic content with detection limits down to 0.07 ng mL−1 and RSD ranging from 4.4% to 13.8%. The recovery studies with spiked real effluent samples at low levels of chlorophenols ranged from 59.8% to 142.1% for the lowest level (0.5 ng mL−1) and from 79.6% to 115.8% for the highest spiked level (2 ng mL−1). These results show the suitability of the proposed method to monitor chlorophenols in complex sampl...

Micellar solid-phase microextraction (MSPME) coupled to gas chromatography-mass spectrometry (GC-MS) has been used to obtain partition coefficients of a group of 18 substituted aromatic hydrocarbons to ionic and nonionic micelles. Statistical and factor analyses have been utilized to establish some general equations relating molecular descriptors of non-substituted polycyclic aromatic hydrocarbons and their partition coefficients obtained by MSPME. The obtained equations have correlation coefficients higher than 0.94. They are used to predict hydrocarbon-micelle partition coefficients for a group of hydrocarbons with reported literature values giving a correlation coefficient of 0.98 and a standard deviation of the prediction of 0.182. The predictive model was also applied to substituted polycyclic aromatic hydrocarbons with partition coefficient values obtained by MSPME, with a 69% level of success.

A method for the determination of 11 heterocyclic amines (HAs) in meat extracts by high performance liquid chromatography with electrochemical detection is proposed. The chromatographic method is optimized to obtain both polar and less polar amines in the same chromatographic run, which is a difficult task when using electrochemical detection. The extraction of the meat extracts is carried out using a focused microwave system, a technique applied for first‐time in the extraction of these analytes. The microwave extraction process takes only 5 minutes, an improvement on the extraction times for methods commonly applied to heterocyclic amines in food samples. This screening method allows us to determine HAs in meat extracts with average recoveries of 81.2%, 76.4%, 66.7%, 60.3%, and 63.8%, for granulated meat extract, non‐granulated meat extract, chicken extract, and soup cubes (brands A and B), respectively. The proposed method has an intermediate precision ranging from 6.1 to 12.8%, and detection ...

A procedure for the determination of less polar heterocyclic amines in meat extracts using solid phase microextraction (SPME) coupled to high-performance liquid chromatography (HPLC) with fluorescence detection is presented. Analytes were first extracted from the samples using methanol/NaOH by an ultrasound-assisted method, and then concentrated on a Carbowax-templated resin (CW-TPR) SPME fiber. The extraction conditions such as extractant mixture composition, extraction time and extractions number, were optimized and the need of an extract freezing step previous to SPME is discussed. The detection limits under optimal conditions are in the range of 0.28–1.1 ng g−1. The method was applied to the determination of less polar heterocyclic amines in four commercial meat extracts. Recovery values obtained are higher than 60% for the majority of amines.

The use of mixed hemimicelles of ionic liquid (IL)-based surfactants in a magnetic-based micro-dispersive solid-phase extraction (m-μdSPE) approach is described. Not only is the symmetric monocationic IL-based surfactant 1,3-didodecylimidazolium bromide (C12C12Im-Br) studied for first time in m-μdSPE, but double-salt (DS) IL (DSIL)-based surfactants are also examined. Nine DSIL-based surfactants were formed by combination of C12C12Im-Br with other IL-based surfactants, including nonsymmetric monocationic and dicationic ILs combined at three different molar fractions. The analytical application was focused on the determination of a group of eight phenols, including bisphenol A, in water samples. The best results were obtained with the DSIL formed by C12C12Im-Br (molar fraction 0.5) and 1-hexadecyl-3-methylimidazolium bromide (C16MIm-Br), after proper optimization of the overall method in combination with high-performance liquid chromatography (HPLC) and diode-array detection (DAD). The optimum conditions for 100 mL of water samples require a small amount (10 mg) of Fe3O4 magnetic nanoparticles, a low content (5.0 mg of C12C12Im-Br and 3.9 mg of C16MIm-Br) of the selected DSIL, pH 11, a sonication time of 2.5 min, and an equilibration time of 5 min with the aid of NdFeB magnets, followed by elution of phenols, evaporation, and reconstitution with 0.5 mL of acetonitrile. The overall m-μdSPE-HPLC-DAD method is characterized for limits of detection down to 1.3 μg · L(-1), intraday relative standard deviations lower than 13 % (n = 3), and interday relative standard deviations lower than 17 % (n = 9), with a spiking level of 15 μg · L(-1); with enrichment factors between 15.7 and 141, and average relative recoveries of 99.9 %.