Nanostructured alkyl carboxylic acid-based restricted access solvents: Application to the combined microextraction and cleanup of polycyclic aromatic hydrocarbons in mosses

Environmentally-friendly supramolecular solvent microextraction method for rapid identification of Sudan I-IV from food and beverages

A new ultrasonically assisted supramolecular solvent-based microextraction (UA-SUPRAS-ME) method has been reported. This technique is one of the green methods for rapid microextraction and determination of Sudan I, II, III and IV dyes from food and beverage samples and the study investigated the effects of various parameters such as centrifugation time, 1-octanol volume, pH, supramolecular solvent type, THF volume, ultrasonication time on the optimization of the microextraction process. Addition and recovery of the method were carried out at two different concentrations (10 and 100 ng mL^-1) to food and beverage samples and the accuracy of the method was determined. Sudan I dye was detected in red pepper and hot sauce from food samples. Extraction recovery values were found between 90.6 % and 102.5 % which are promising compared to many other methods.

Exploring polar hydrophobicity in organized media for extracting oligopeptides: application to the extraction of opiorphin in human saliva

Supramolecular solvents (dubbed SUPRAS) are gaining momentum as extractants of compounds of interest from complex matrixes such as foodstuff and biological and environmental samples. However, their powerful extraction mechanism, based on multiligand ability for solute binding, fails when applied to very polar compounds, hindering their applicability to the extraction of highly polar metabolites. In this work, we introduce the synthesis, characterization, and application of a new kind of SUPRAS formed by heptafluorobutyric acid (HFBA). The polar hydrophobicity of this perfluorinated acid results in a SUPRAS, which coacervates at acidic pHs, that shows a great capability to extract amino acids and oligopeptides (recoveries in the range 81-105%) with nonpolar alkyl, cyclic or aromatic side chain substituents (with log D > -3.62). To further demonstrate the potential of this novel SUPRAS, an analytical methodology for the determination of opiorphin in real saliva samples was developed and fully validated. The HFBA-based SUPRAS was synthetized in situ from 950 µL of stabilized saliva, by the addition of 150 µL of HFBA and 400 µL of HCl 37% (v/v). The resulting SUPRAS was directly injected into a LC-MS/MS system for further quantification. Quantitative recoveries in the range of 87-110% were obtained with relative standard deviations below 20%. The HFBA-based SUPRAS is, therefore, capable of efficiently extracting opiorphin from saliva samples and shows a high potential for the determination of several amino acids and oligopeptides from biological samples.

Restricted access supramolecular solvent based magnetic solvent bar liquid-phase microextraction for determination of non-steroidal anti-inflammatory drugs in human serum coupled with high performance liquid chromatography-tandem mass spectrometry

A hexafluroisopropanol (HFIP)-alkanol supramolecular solvent (SUPRAS) based magnetic solvent bar (MSB) liquid-phase microextraction (LPME) method was proposed for extraction of non-steroidal anti-inflammatory drugs (NSAIDs, including ketoprofen, naproxen, indomethacin and diclofenac) in human serum. The restricted access HFIP-alkanol SUPRAS was prepared by injecting a mixture of HFIP and alkanol into water. A stainless-steel needle was inserted into a piece of hollow fiber to prepare a magnetic bar. Then the magnetic bar was dipped in SUPRAS to impregnate the wall pores of the hollow fiber, followed by placing it into the serum sample for extraction. Only 4 μL of SUPRAS was consumed per bar. The MSB not only functioned for stirring, but also played the role of extraction and magnetic separation. Under the optimal extraction conditions (seven MSBs, extraction time 33 min and stirring rate 730 rpm), which was obtained by one variable-at-a-time and response surface methodology, the novel MSB-LPME was coupled with high performance liquid chromatography-tandem mass spectrometry to determine NSAIDs in human serum. The method showed a good linear relationship (correlation coefficients ≥ 0.9939). Method limits of detection and method limits of quantitation were in the range of 0.25-0.95 μg L^-1 and 0.83-3.16 μg L^-1, respectively. The recoveries for the spiked human serum samples ranged from 86.8% to 125.1% with intra- and inter-day relative standard deviations less than 9.2% and 18.1%, respectively. Moreover, the method did not require a protein precipitation step, and matrix effects of 72.8%-117.7% showed little interference with mass spectrometry detection, which was due to the double cleanup provided by the restricted access property of SUPRAS and the filtration capacity of hollow fiber. The HFIP-alkanol SUPRAS-based MSB-LPME method proved to be simple, highly efficient and environment-friendly for the pretreatment of serum/plasma.

A new sample treatment strategy based on simultaneous supramolecular solvent and dispersive solid-phase extraction for the determination of ionophore coccidiostats in all legislated foodstuffs

A single-step sample treatment, for the simultaneous extraction and clean-up for the determination of ionophore coccidiostats in EU legislated foodstuffs, is here proposed. The treatment is based on the combination of: (i) a supramolecular solvent with restricted access properties (SUPRAS-RAM), spontaneously formed by the addition of hexanol, water and THF to the sample; and (ii) dispersive solid phase extraction (dSPE). The SUPRAS-RAM extract was directly compatible with LC-MS/MS and no further re-extraction, evaporation or cleanup procedures were necessary. SUPRAS-RAM efficiently extracted the ionophores (recoveries in milk, eggs, fat, liver, kidney, and chicken and beef muscle were in the range 71-112%) and removed proteins and carbohydrates, whereas dSPE removed fats and other lipophilic compounds. The method was validated following the European Commission Decision 2002/657/EC. Detection limits (0.004-0.07 µg kg^-1) were far below the maximum residue limits (1-150 µg kg^-1). Method analytical and operational characteristics were suitable for routine determination of ionophores.

A critical review on plant biomonitors for determination of polycyclic aromatic hydrocarbons (PAHs) in air through solvent extraction techniques

Polycyclic aromatic hydrocarbons (PAHs) are hydrocarbons having two or more fused aromatic rings, released from natural (like forest fires and volcanic eruption) as well as man-made sources (like burning of fossil fuel & wood, automobile emission). They are persistent priority pollutants and continue to last for a long time in the environment causing severe damage to human health owing to their genotoxicity, mutagenicity and carcinogenicity. The study of PAHs in environment has therefore aroused a global concern. PAHs adsorption to plant cell wall is facilitated by transpiration and plant root lipids which help PAHs transfer from roots to leaves and stalks, causing more accumulation of contaminants with the increase in lipid content. Hence, these bioaccumulators can be utilized as biomonitors for indirect assessment of ambient air pollution. Efficacy of specific plants, lichens and mosses as useful biomonitors of airborne PAHs pollution has been discussed in this review along with prevalent classical and modified extraction techniques coupled with proper analytical procedures in order to gain an insight into the assessment of atmospheric PAHs concentrations. Different modern and modified solvent extraction techniques along with conventional Soxhlet method are identified for extraction of PAHs from accumulative bioindicators and analytical methods are also developed for accurate determination of PAHs. Process parameters like choice of solvent, temperature, time of extraction, pressure and matrix characteristics are usually checked. An approach of biomonitoring of PAHs using plants, lichens and mosses has been discussed here as they usually trap the atmospheric PAHs and mineralize them.

Micelle-based restricted access ion-pair microextraction of phosphate at trace levels in water samples for separation, preconcentration and determination

A new and simple micelles-rich restricted access supramolecular solvent-based liquid phase microextraction method (RASUPRASs-LPME) based on the ion-pair complex formation of phosphate (PO4 3-) ions with ammonium heptamolybdate and malachite green in acidic medium was developed. The phosphate ion concentration after microextraction of the ion-pair complex to the hexagonal aggregates of decanoic acid (DA) was measured with micro-volume UV-Vis spectrophotometer at 625 nm. All analytical parameters which are effective on the method such as acid type and concentration, supramolecular solvent volume, amount of the components forming the complex, sample volume, were optimized. The preconcentration factor (PF), limit of detection (LOD) and limit of quantification (LOQ) for the developed method was found to be 15, 9.6 and 32.1, respectively. The RA-SUPRAs-LPME method was finally applied for the analysis of the phosphate content of different types of water samples.

Twenty years of supramolecular solvents in sample preparation for chromatography: achievements and challenges ahead

Supramolecular solvents (SUPRAS) have progressively become a suitable alternative to organic solvents for sample preparation in chromatographic analysis. The inherent properties of these nanostructured solvents (e.g. different polarity microenvironments, multiple binding sites, possibility of tailoring their properties, etc.) offer multiple opportunities for the development of innovative sample treatment platforms not approachable by conventional solvents. In this review, major achievements attained in the combination SUPRAS-chromatography in the last 20 years as well as the challenges that should be addressed in the near future are critically discussed. Among achievements, particular attention is paid to the theoretical and practical knowledge gained that has helped make substantial progress in the area. In this respect, advances in the understanding of the mechanisms involved in SUPRAS formation and SUPRAS-solute interactions driving extractions are discussed, with a view to the setting up of knowledge-based extraction procedures. Likewise, the strategies followed to improve the compatibility of SUPRAS extracts with liquid and gas chromatography and adapt SUPRAS-based extractions to different formats are presented. Ongoing efforts to apply SUPRAS in multicomponent extractions and synthesize tailored SUPRAS for the development of innovative sample treatments are highlighted. Among challenges identified, discussion is focused on the automation of SUPRAS-based sample treatment and the elucidation of SUPRAS nanostructures, which are considered essential for their acceptance in routine labs and the design of tailored SUPRAS with programmed functions. Graphical abstract.

Supramolecular solvent-based high-throughput sample treatment platform for the biomonitoring of PAH metabolites in urine by liquid chromatography-tandem mass spectrometry

Monohydroxylated polycyclic aromatic hydrocarbons (OH-PAHs), present in human urine at trace concentrations (viz. from ng L^-1 to μg L^-1), are considered the main biomarkers of human exposure to PAHs. In this work, we report a simple and high-throughput sample treatment platform to facilitate the biomonitoring of OH-PAHs by making it easier, greener and most cost-effective. This platform is based on the integration of analyte extraction and sample cleanup in a single step by the use of supramolecular solvents with restricted access properties (SUPRAS-RAM). The SUPRAS was spontaneously formed in situ in the urine by the addition of a colloidal suspension of decanoic acid in THF. Metabolites from naphthalene, fluorene, phenanthrene and pyrene were quantitatively extracted (absolute recoveries in the range 91-109%). Polysaccharides and proteins in the urine were excluded from extraction by physical and chemical mechanisms, which allowed the direct analysis of the SUPRAS extract by liquid chromatography tandem mass spectrometry. Absolute matrix effects for OH-PAHs were in the range 92-103%. Method quantification limits for OH-PAHs, without the need for evaporation of the SUPRAS extracts, were in the interval 1.0-6.7 ng L^-1. The precision, evaluated in terms of repeatability and reproducibility, varied between 1.1 and 13.8%. The method was successfully applied to the analysis of urine from 16 smoking and non-smoking volunteers. Both analytical and operational features of this method make it suitable to evaluate human exposure to PAHs.

Alternative Green Extraction Phases Applied to Microextraction Techniques for Organic Compound Determination

The use of green extraction phases has gained much attention in different fields of study, including in sample preparation for the determination of organic compounds by chromatography techniques. Green extraction phases are considered as an alternative to conventional phases due to several advantages such as non-toxicity, biodegradability, low cost and ease of preparation. In addition, the use of greener extraction phases reinforces the environmentally-friendly features of microextraction techniques. Thus, this work presents a review about new materials that have been used in extraction phases applied to liquid and sorbent-based microextractions of organic compounds in different matrices.

Multifunctional green supramolecular solvents for cost-effective production of highly stable astaxanthin-rich formulations from Haematococcus pluvialis

The interest of food industry to merchandise natural astaxanthin is growing up. However, it confronts scientific and technological challenges mainly related to its poor water solubility and chemical instability. Here, we present a new quick and efficient green process to simultaneously extract, encapsulate and stabilize astaxanthin from Haematococcus pluvialis. The process is based on the hitherto unexplored combination of supramolecular solvents (SUPRAS), nanostructured liquids generated from amphiphiles through sequential self-assembly and coacervation, and nanostructured lipid carriers (NLCs). These novel nanosystems were characterized by means of dynamic light scattering, AFM and cryoSEM, revealing spherical particles of ∼100 nm. Their antioxidant activity was measured by ORAC (20.6 ± 3.9 μM TE) and α-TEAC (2.92 ± 0.58 µM α-TE) assays and their in vitro capacity to inhibit ROS by DHE probe. Results showed that the SUPRAS-NLCs proposed yield high extraction and encapsulation efficiencies (71 ± 4%) in combination with a remarkable time stability (180 d, 4 °C).

Room temperature phosphorescence of five PAHs in a synergistic mesoporous silica nanoparticle-deoxycholate substrate

A synergistic mesoporous silica nanoparticle-sodium deoxycholate (mPS-NaDC) substrate was developed for room temperature phosphorimetry. The synergistic substrate exhibited rapid and strong RTP-inducing ability against temperature variation. NaDC might adsorb on the inner surface of mPS pore by possible hydrogen bonding and protected the triplet state of polycyclic aromatic hydrocarbons (PAHs) with different molecular sizes. Two mPSs named LPMS1 and LPMS2 with pore size of 3.05 and 3.83nm were synthesized and optimized in inducing RTP, and the latter, LPMS2, was selected as an ideal substrate because of its stronger protection ability to the triplet and good stability. Dibromopropane and cyclohexane were also used as assistant phosphorescence-inducers. All results demonstrated the feasibility and application potential of synergistic mPS-NaDC substrate in phosphorimetry. The interaction detail of NaDC and inner surface of selected mPS still needs to be explored in future.