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In this work, several potential natural deep eutectic solvents (NADES) were evaluated as sustainable solvents in the development of an ultrasound (US)-assisted extraction method for sulfonamides from soil samples and final determination by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Choline chloride (ChCl) was used as hydrogen bond acceptor (HBA), and different carboxylic acids and alcohols were tested as hydrogen bond donors (HBDs) in different molar ratios in order to find the optimum combination able to form appropriated NADES for the extraction of sulfonamides. Among the different mixtures tested, the one consisting of ChCl:1,3-propanediol in a molar ratio of 1:4 showed the better physico-chemical properties and was selected for the US-assisted extraction of sulfonamides. Under optimum conditions, no matrix effect was observed and quantitative recoveries, ranging from 81.9 % to 103.9 % with relative standard deviations (RSDs) lower than 8 % were obtained, reaching limits of quantification within the range 8.5–31 µg Kg−1, depending upon the analyte. In addition, after evaluation by AGREEprep, Sample Preparation Metric of Sustainability (SPMS) and Blue Applicability Grade Index (BAGI) metrics tools, the proposed method was found to be superior to other published methods in terms of safety and environmental impact with good applicability potential.

Nowadays, molecularly imprinted polymers (MIPs) are well established and are considered excellent materials for performing selective extractions. However, with the progressive implementation of the principles of green chemistry, it is necessary to find greener alternatives for both the synthesis and further use of MIPs in sample preparation. Accordingly, in the present work, different deep eutectic solvents (DES, both hydrophilic and hydrophobic), as an alternative to conventional organic solvents (i.e., toluene), were evaluated as porogens for the synthesis of imprinted fibers (monoliths), using fused silica capillaries as molds, for solid-phase microextraction (SPME). From this study, the polymer prepared with propazine (dummy template), methacrylic acid (monomer), ethylene glycol dimethacrylate (cross-linker), and a formic acid:L-menthol (1:1) DES (porogen) showed the best performance for selective rebinding of triazines. After optimization of the different variables involved in SPME, the new imprinted fibers were successfully applied to the extraction of target analytes (desisopropylatrazine, desethylatrazine, simazine, and atrazine) from soil sample extracts, providing relative recoveries ranging from 75.7 to 120.1%, reaching limits of detection within the range of 6.2-15.7 ng g-1, depending upon the analyte.

In this work, the use of a hydrophobic natural deep eutectic solvent (NADES) as supported liquid membrane (SLM) for hollow fiber liquid-phase microextraction (HF-LPME) of triazines is proposed. The combination of formic acid:L-menthol (2:1) was selected as optimum. FT-IR spectra of selected NADES and its components associated to Fig. S1 of paper submitted to Microchemical Journal are provided as csv files as follow: FigS1 (menthol); FigS1 (formic acid); FigS1 /NADES).

In this work, the use of a hydrophobic natural deep eutectic solvent (NADES) as supported liquid membrane (SLM) for hollow fiber liquid-phase microextraction (HF-LPME) of triazines is proposed. The combination of formic acid:L-menthol (2:1) was selected as optimum. The optimized HF-LPME procedure was applied to the analysis of an artificial water containing humic acids, tap and river water, and urine samples by HPLC with UV detection at 268 nm. The chromatographic data associated to Fig.6 and 7 of paper submitted to Microchemical Journal are provided as csv files as follows: Fig6a: Milli-Q water; Fig6b; artificial water; Fig7a: Tap water; Fig7b: River water; Fig7c: Urine river. All the samples were spiked with selected sulfonamides at 5 µg/L concentration level.

Molecular imprinting technology is a well-established technique for the obtainment of tailor-made polymers, so-called molecularly imprinted polymers, with a predetermined selectivity towards a target analyte or structurally related compounds. Accordingly, molecularly imprinted polymers are considered excellent materials for sample preparation providing unprecedented selectivity to analytical methods. However, the use of molecularly imprinted polymers in sample preparation still presents some shortcomings derived from the synthesis procedure itself limiting its general applicability. In this regard, molecularly imprinted polymers use to display binding sites heterogeneity and slow diffusion mass transfer of analytes to the imprinted sites affecting their overall performance. Besides, the performance of molecularly imprinted polymers in organic solvents is excellent, but their selective binding ability in aqueous media is considerably reduced. Accordingly, the present review pretends to provide an updated overview of the recent advances and trends of molecularly imprinted polymers-based extraction, focusing on those strategies proposed for the improvement of mass transfer and selective recognition in aqueous media. Besides, with the progressive implementation of Green Chemistry principles, the different steps and strategies for the preparation of molecularly imprinted polymers are reviewed from a green perspective.

The use of molecularly imprinted polymers in sample preparation is nowadays well-established thanks to their ability to provide unprecedented selectivity during extraction and clean-up steps. However, both their synthesis and subsequent use are far from being considered green. Accordingly, in the present chapter, the greenness of the different steps and strategies for the preparation and use of molecularly imprinted polymers in sample preparation is critically reviewed, and recent alternatives to make the use of molecularly imprinted polymers more sustainable are provided.

Highly developed analytical instrumentation (i.e., chromatographic techniques coupled to mass spectrometry) is now available in most analytical laboratories; thus, it is possible to determine any kind of organic compound. However, the direct analysis of crude sample extracts negatively affects the quality of the obtained results in terms of both precision and accuracy, and potentially damages the detection equipment. Therefore, an adequate sample preparation should be performed before final determination in order to reduce the matrix effect during the subsequent measurement step. Moreover, sample preparation allows an increase in the concentration (trace enrichment) of target analytes, which in turn allows researchers to reach the low-detection limits necessary to meet the current stringent regulations established by national and international authorities. Other sample-preparation objectives–such as reducing both the sample size and the amountof organic solvents and glassware to be used, facilitating automatization, and increasing sample throughput—have been established during the last decades.

In this work, the use of a hydrophobic natural deep eutectic solvent (NADES) as supported liquid membrane (SLM) for hollow fiber liquid-phase microextraction (HF-LPME) of sulfonamides is proposed. The combination of formic acid:L-menthol (1:1) was selected as optimum. The optimized HF-LPME procedure was applied to the analysis of an artificial water containing humic acids, tap and river water samples by HPLC with UV detection at 268 nm. The chromatographic data associated to Fig.7 of paper published in Advances of Sample Preparation are provided as csv files as follows: Fig7Aa: Milli-Q water; Fig7Ab; artificial water; Fig7Ba: Tap water (a); Fig7Bb: Manzanares river; Fig7Bc: Jarama river. All the samples were spiked with selected sulfonamides at 10 µg/L concentration level.

This work proposes the use of a hydrophobic natural deep eutectic solvent (NADES) as a supported liquid membrane (SLM) for hollow fiber liquid phase microextraction (HF-LPME) of triazines. NADES were prepared using L-menthol as hydrogen bond acceptor combined with different hydrogen bond donors of natural origin: carboxlylic acids, alcohols and amines. Studies were carried out to determine whether the prepared NADES met the necessary requirements to be used as a SLM, such as stability in the HF and compatibility with HPLC. Then, the ability of each prepared NADES to extract 6 triazine herbicides by HF-LPME from aqueous samples was evaluated. Among them, the mixture L-menthol: formic acid (molar ratio 1:2) provided better extraction results and was selected as SLM. The influence the different parameters on extraction efficiency such as pH of both sample and acceptor solution, salting-out effect, extraction time and stirring rate on the extraction efficiency was carefully studied and optimized. The optimized HF-LPME procedure was applied to the analysis of aqueous samples such as artificial water containing humic acids, tap water, river water and urine, with excellent clean-up ability for all samples analyzed. Relative recoveries ranged from 68 to 128 %, and the LODs and LOQs obtained for the 6 triazines were 0.75–3.1 µg/L and 2.5–10.3 µg/L, respectively, depending on the analyte and the kind of sample. Additionally, according to the AGREEprep tool assessment, the proposed method appears as a greener approach compared to other microextraction methods reported in the literature for the analysis of triazines in water samples.

Sample preparation is still considered the bottle-neck of the whole analytical process. Nowadays, several sample preparation techniques are available, however all of them suffer from lack of the selectivity. At this regard, molecularly imprinted polymers (MIPs) are considered excellent materials able to perform selective extractions. Recently, new objectives in sample preparation have been set, including to use smaller initial sample sizes; to facilitate automation; and, to minimize the amount of glassware and organic solvents needed. MIP incorporation to other microextraction techniques offers a new strategy in order to fulfil current sample preparation requirements. However, even using MIPs, the complexity of the sample can affect recoveries of target analytes, negatively affecting the analytical method precision and accuracy. The use of a porous membrane, as a protective sleeve, is one of the simplest approaches to circumvent the difficulties mentioned above in the analysis of complex and “dirty” samples. Accordingly, the present paper pretends to provide an overview of micro-extraction approaches developed during last years based on the use of membrane-protected MIPs and how such approaches have open new pathways in the development of liquid phase micro-extraction methods with improved analytical characteristics. Advantages, drawbacks and future expected trends are also critically assessed.

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.

In the last decades analytical methods have focused on the determination of target analytes at very low concentration levels. This has been accomplished through the use of traditional analytical methods that usually require high reagent consumption, expensive equipment and long pretreatment steps. Thus, there is a demand for simple, rapid, highly selective and user-friendly detection procedures. Quantum dots (QDs) are semiconductor fluorescent nanomaterials with unique optoelectronic properties that have shown great potential for the development of fluorescence probes. Besides, the combination of QDs with molecularly imprinted polymer (MIPs), synthetic materials with selective recognition, have been proposed as useful materials in the development of optical sensors. The resulting MIP-QDs optical sensors integrate the advantages of both techniques: the high sensitivity of QDs-based fluorescence sensors and the high selectivity of MIPs. This review gives a brief overview of the strategies for the synthesis of MIPs-QDs based optical sensors, highlighting the modifications in the synthesis procedure that improve the sensor performance. Finally, a revision of recent applications in sensing and bioimaging is presented.

The use of molecularly imprinted polymers in sample preparation as selective sorbent materials has received great attention during the last years leading to analytical methods with unprecedented selectivity. However, with the progressive implementation of Green Analytical Chemistry principles, it is necessary to critically review the greenness of synthesis and further use of molecularly imprinted polymers in sample preparation. Accordingly, in the present review, the different steps and strategies for the preparation of molecularly imprinted polymers, the used reagents, as well as their incorporation to microextraction techniques are reviewed from a green perspective and recent alternatives to make the use of molecularly imprinted polymers more sustainable are provided.

Magnetic nanoparticles have been surface modified by molecular imprinting and evaluated as selective sorbents for the extraction of triazines from environmental waters. The use of propazine as template allowed us to synthesize a selective material able to simultaneously recognize and selective extract not only the template but also several other herbicides of the same family. A magnetic molecularly imprinted-based dispersive solid-phase extraction procedure was developed and fully optimized. Magnetic molecularly imprinted polymer particles can be easily collected and separated from liquid solvents and samples with the help of an external magnetic field, avoiding in that way any centrifugation or filtration steps, which represents a remarkable advantage over traditional procedures. Under optimum conditions, selective extraction of several triazines (cyanazine, simazine, atrazine, propazine, and terbutylazine) from environmental water samples was performed prior to final determination by high-performance liquid chromatography with diode-array detection. Recoveries for the studied triazines were within the range of 75.2–94.1%, with relative standard deviations lower than 11.3% (n = 3). The limits of detection were within 0.16–0.51 µg/L, depending upon the triazine and the type of sample analyzed.

Highly developed analytical instrumentation (i [...]