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Deep eutectic solvents have quickly attracted the attention of researchers because they better meet the requirements of green chemistry and thus have the potential to replace conventional hazardous organic solvents in some areas. To better understand the nature of these mixtures, as well as expand the possibilities of their use in different industries, a detailed examination of their physical properties, such as density, viscosity, the nature of the interactions between their constituents, the phase diagrams, depression of their melting point, and interpretation of these results is necessary. In this work, the mixtures of tetrabutylammonium bromide (TBAB) and nonanoic acid (NA) in different molar ratios are theoretically and experimentally investigated by applying a phase diagram constructed on the basis of differential scanning calorimetry measurements and COSMO-RS model. Spectral properties are investigated based on Fourier transform infrared spectroscopy and density functional theory. The observed eutectic point indicates the formation of a DES in the TBAB-NA system in a 1:2 molar ratio. This is due to the presence of hydrogen bonds between the carboxyl group from the NA molecule and the bromine atom from the TBAB molecule. Other eutectic mixtures are most likely the solutions of TBAB in NA, in which hydrogen bonds predominate between acid molecules.

In this study, a novel approach for effective liquid-liquid microextraction based on deep eutectic solvent (DES) decomposition was suggested for the first time. It was established that DESs synthesized from tetrabutylammonium bromide and long-chain alcohols decomposed in aqueous phase resulting in in situ dispersion of organic phase and extraction of hydrophobic analyte(s). It this process long-chain alcohol acted as an extraction solvent and tetrabutylammonium bromide acted as a dispersive agent and promoted mass transfer between aqueous and organic phases as a salting out agent. Phenomenon of DES decomposition was studied in detail and applied for separation and preconcentration in chemical analysis for the first time. The developed approach was applied for 17β-estradiol microextraction from transdermal gel samples as a proof-of-concept example. The results showed that the in situ dispersed organic phase obtained can provide efficient extraction of 17β-estradiol with good extraction recovery (95 ± 5%) and excellent reproducibility (6%). The reported approach proves to be fast, simple, and inexpensive.

Miniaturized extraction techniques are well established in analytical protocols following the guidelines of green chemistry. In spite of this, analytical chemistry researchers continue to look for ...

The current short review is devoted to cloud point extraction (CPE). It provides information about history, present status and future trends in the development of this method. After a brief overview of the review papers on CPE, the attention is focused on applications of nanoparticles (NPs) in CPE procedures. Two main directions are discussed: (i) participation of NPs as carriers of different analytes (CoII, CrIII,VI, CuII, FeIII, NiII, PbII, VIV,V, ZnII and a variety of organic substances); and (ii) participation of NPs in sensing events thanks to their high absorption coefficient and color-tunable optical properties. Except for metallic NPs containing pure metals (Ag or Au) or metal oxides/hydroxides, such as Al2O3, Co(OH)2, Fe2O3, Fe3O4, SnO2, TiO2, ZrO2, the paper describes the uses of curcumin and carbon based NPs (nanodiamonds, multi-walled carbon nanotubes, graphene oxide NPs and reduced graphene oxide NPs) in innovative approaches involving CPE. 68 references are included.

In the present work, fourteen cultivars of Prunus domestica were analyzed to investigate their phenolic pattern with the purpose of using the leaves as potential resources of bioactive compounds in the pharmaceutical and food industry. Microwave-assisted extraction (MAE), dispersive liquid–liquid microextraction and sugaring-out liquid–liquid extraction techniques were optimized in order to obtain an exhaustive multi-component panel of phenolic compounds. The best phenolic-enriched recovery was achieved using MAE in water:methanol (30:70), and this procedure was further applied for quantitative analysis of phenolic compounds in real samples. In order to prove the safeness of these extracts, the biological potential of the Prunus cultivars was tested by several in vitro antioxidant and enzyme inhibitory assays. Moreover, their cytotoxicity was evaluated on human gingival fibroblasts (HGFs), and in most of the cases the treatment with different concentrations of extracts didn't show cytotoxicity up to 500 μg/mL. Only ‘Carpatin’ and ‘Minerva’ cultivars, at 250 and 500 μg/mL, reduced partially cell viability of HGFs population. Noteworthy, Centenar cultivar was the most active for the α-glucosidase inhibition (6.77 mmolACAE/g extract), whereas Ialomița cultivar showed the best antityrosinase activity (23.07 mgKAE/g extract). Overall, leaves of P. domestica represent a rich alternative source of bioactive compounds.

A green, simple, accurate and highly sensitive sequential injection lab-at-valve procedure has been developed for the simultaneous determination of ascorbic acid (Asc) and rutin using 18-molybdo-2-phosphate Wells-Dawson heteropoly anion (18-MPA). The method is based on the dependence of the reaction rate between 18-MPA and reducing agents on the solution pH. Only Asc is capable of interacting with 18-MPA at pH 4.7, while at pH 7.4 the reaction with both Asc and rutin proceeds simultaneously. In order to improve the precision and sensitivity of the analysis, to minimize reagent consumption and to remove the Schlieren effect, the manifold for the sequential injection analysis was supplemented with external reaction chamber, and the reaction mixture was segmented. By the reduction of 18-MPA with reducing agents one- and two-electron heteropoly blues are formed. The fraction of one-electron heteropoly blue increases at low concentrations of the reducer. Measurement of the absorbance at a wavelength corresponding to the isobestic point allows strictly linear calibration graphs to be obtained. The calibration curves were linear in the concentration ranges of 0.3–24 mg L −1 and 0.2–14 mg L −1 with detection limits of 0.13 mg L −1 and 0.09 mg L −1 for rutin and Asc, respectively. The determination of rutin was possible in the presence of up to a 20-fold molar excess of Asc. The method was applied to the determination of Asc and rutin in ascorutin tablets with acceptable accuracy and precision (1–2%).

Green chemistry is an important way of thinking in the field of chemistry and aims to conduct processes in accordance with the principles of sustainable development. It is the application of a wide range of principles that minimize the impact of both chemical processes and products on the environment. And what about analytical chemistry? There is no doubt that analytical chemistry plays an important role in the sustainable development of the planet. However, this only applies if analytical procedures are of high quality (sensitive, precise, and accurate) and also in line with the principles of environmental sustainability. This essay presents a brief discussion of the evolution of green chemistry and its multidimensional impacts, including the “industry” of analytical chemistry as well as academic education and research. We emphasize the difference between the term “sustainability” and “greenness.” Therefore, at least basic information on sustainability in analytical chemistry is provided. We hope that our considerations will inspire analytical chemists and will contribute to the further development of both green analytical chemistry and sustainable analytical chemistry.

A cloud-point extraction-chromogenic system containing vanadium(V), 1-(2-thiazolylazo)-2-naphthol (TAN), H 2 O 2 and Triton X-100 was investigated. The optimum conditions for vanadium extraction and spectrophotometric determination were found to be: concentrations of TAN and H 2 O 2 (5 × 10 − 5 and 3.0 × 10 − 4 mol L − 1 , respectively), mass fraction of Triton X-100 (3%), acidity (5 × 10 − 3 mol L − 1 H 2 SO 4 ), incubation time (60 min for hot plate or 10 min for microwave oven) and wavelength (607 nm). The composition of the extracted species was determined (V: TAN: O 2 2 – = 1: 1: 2), and the geometries of four possible structures, which differ by the coordination mode of O 2 2 − , were optimized at the BLYP/cc-pVDZ level of theory. The UV–Vis spectra were calculated and compared with the experimental spectra. Species with two monodentate peroxide ligands are present in the extract, along with species containing one monodentate and one bidentate peroxide. The effect of foreign ions was studied, and the analytical characteristics of the developed procedure were determined. Spectral interference of copper(II) was observed; however, it can be corrected mathematically by measuring the absorbance at 580 and 610 nm. Iron(III) can be efficiently masked with HPO 4 2 − . The method was applied for analysis of various samples. Beer's law was obeyed up to 0.76 μg mL − 1 of vanadium. The limits of detection (LOD) and determination (LOQ) and the molar absorptivity ( e 607 ) were 1.4 ng mL − 1 , 4.8 ng mL − 1 and 8.84 × 10 4 L mol − 1 cm − 1 , respectively.

Introduction For the determination of harpagoside and the wide phenolic pattern in Harpagophytum procumbens root and its commercial food supplements, dispersive liquid–liquid microextraction (DLLME), ultrasound-assisted DLLME (UA-DLLME), and sugaring-out liquid–liquid extraction (SULLE) were tested and compared. Objectives In order to optimise the extraction efficiency, DLLME and UA-DLLME were performed in different solvents (water and aqueous solutions of glucose, β-cyclodextrin, (2-hydroxypropyl)-β-cyclodextrin, sodium chloride, natural deep eutectic solvent, and ionic liquid). Material and Methods The plant material was ground and sieved to obtain a uniform granulometry before extraction. Commercial food supplements, containing H. procumbens are commercially available in Italy. Results The most effective sodium chloride-aided-DLLME was then optimised and applied for analyses followed by HPLC-PDA. For comparison, microwave-assisted extraction was performed using the same solvents and the best results were obtained using 1% of β-cyclodextrin or 15% of sodium chloride. Conclusion All commercial samples respected the European Pharmacopoeia monograph for this plant material, showing a harpagoside content ≥ 1.2%. Copyright © 2017 John Wiley & Sons, Ltd.

Deep eutectic solvents (DESs), as a new type of green solvents, have recently been getting a great deal of interest in many areas of science and technology. In this minireview, we briefly discuss the analytical applications of DESs published during the past five years. We focus mainly on various DES-based (micro)extraction procedures. The applications of these techniques are summarized in the tables.

A fully automated alkaline-induced salting-out homogeneous liquid-liquid extraction (AI-SHLLE) procedure coupled with in-line organic-phase detection by an optical probe has been suggested. Diclofenac was used as a proof-of-concept analyte. The method is based on the oxidation of diclofenac with potassium ferricyanide in an alkaline medium followed by separation of the acetonitrile phase from the homogeneous sample solution and simultaneous extraction of the derivative. Sodium hydroxide serves as both the alkaline agent for the derivatization of diclofenac and as the salting-out agent for the acetonitrile-rich phase formation. Absorbance of the derivative in the acetonitrile-rich phase was measured in-line using an optical probe. The calibration graph was linear over the range of 2.5-60µmolL-1 with the regression coefficient equal to 0.9997. The LOD calculated from the calibration plot based on 3σ was 0.8µmolL-1. The sample throughput was 7 samplesh-1. The method was applied for the determination of diclofenac in spiked saliva samples and pharmaceutical preparations and the results were compared with those obtained by the reference method.

Switchable solvents represent a new solvent the use of which is in line of consideration of Green chemistry. In this work, a.novel, green, ligandless switchable solvent based liquid phase microextraction method (LL-SHS-LPME) for preconcentration and determination of nickel was developed. The reversible change of hydrophilicity of 1-ethylpiperidine after exposing to CO2 was the key property allowed simple and effective extraction process. The factors influencing the extraction procedure, including pH, type and volume of switchable solvent volume, way for removing of CO2, vortexing time, and matrix effect were studied. The accuracy of the developed method was evaluated by the analysis of the certified reference materials and addition-recovery test. The developed extraction method was successfully applied for determination of nickel in food and cigarette samples. (C) 2017 Elsevier B.V. All rights reserved.

A novel, sensitive and selective method for the spectrophotometric determination of the basic inorganic iodine species was developed based on the vortex-assisted liquid–liquid microextraction (VALLME) of an ion pair formed between colorless tetrabutylammonium cation (TBA) and triiodide anion (I 3 − ). Molecular iodine was determined spectrophotometrically at 295 nm by the measurement of the intrinsic triiodide absorbance after the addition of an excess of TBA iodide to the sample and following VALLME of the ion-pair TBA-I 3 with amyl acetate. The procedure for iodate determination includes the formation of iodine as a result of iodate reduction with TBA-I in acid solution. The new approach was introduced in order to determine iodide or total inorganic iodine content. N -Bromosuccinimide (NBS) was used for the oxidation of iodide to iodate. The excess NBS was removed with oxalic acid. Afterwards, the analysis proceeded as for iodate. The experimental conditions were optimized and found to be: 0.04 mol L − 1 HCl; 0.12 mmol L − 1 NBS (only for iodide, total iodine); 1 mmol L − 1 and 1.4 mmol L − 1 TBA-I for iodide and iodate determination, respectively; 150 μL of amyl acetate as the extraction solvent; vortexing, 20 s at 3000 rpm; and centrifugation, 2 min at 3000 rpm. The calibration plot was linear in the range 3.8–63 (R 2 = 0.994) and 5.2–88 (R 2 = 0.998) μg L − 1 of iodide (as I − ) and iodate (as IO 3 − ), respectively. The calibration curve for iodine determination (as I 2 ) is satisfactorily described by the second-order equation (R 2 = 0.999) in the concentration range 6.4–76.2 μg L − 1 (as I − ). The limit of detection (LOD) was 1.1, 2.3 and 1.5 μg L − 1 of iodide, iodine (as I − ) and iodate, respectively. The suggested procedure was successfully applied for the determination of iodide, iodate and iodine in salt, sea and mineral water samples. The accuracy of the method was assessed through comparison with reference methods and by recovery testing.

A novel automated procedure for analysis of solid samples based on the on-line dissolution of solid sample and sugaring-out reagent in water-acetonitrile mixture coupled with sugaring-out homogenous liquid-liquid extraction was developed. The procedure was performed in a mixing chamber of a stepwise injection analysis manifold. The performance of the suggested approach was demonstrated by the determination of 2,4-dichlorobenzyl alcohol, amylmetacresol, Yellow Orange S, Azo Rubine and Ponceau 4R in pharmaceutical samples. After phase separation, the upper acetonitrile phase containing 2,4-dichlorobenzyl alcohol, amylmetacresol and lower aqueous phase containing artificial dyes were sequentially analyzed. Under optimal experimental conditions the linear ranges were found to be 0.1–10 mg L− 1 for 2,4 dichlorobenzyl alcohol, 0.5–50 mg L− 1 for amylmetacresol, and 1–100 mg L− 1 for artificial dyes. The sample throughput was 10 h− 1. The proposed method was successfully applied for the automated analysis of commercial throat lozenges and the analytical results agreed fairly well with the results obtained by reference HPLC-UV method.

Introduction The analysis of plant and herbal samples is a challenging task for analytical chemists due to the complexity of the matrix combined with the low concentration of analytes. In recent years different liquid-phase microextraction (LPME) techniques coupled with a variety of analytical equipment have been developed for the determination of both organic and inorganic analytes. Objective Over the past few years, the number of research papers in this field has shown a markedly growing tendency. Therefore, the purpose of this review paper is to summarise and critically evaluate research articles focused on the application of LPME techniques for the analysis of plant and herbal samples. Results Due to the complex nature of the samples, the direct application of LPME techniques to the analysis of plants has not often been done. LPME techniques as well as their modalities have been commonly applied in combination with other pretreatment techniques, including a solid-liquid extraction technique supported by mechanical agitation or auxiliary energies for plant analysis. Applications and the most important parameters are summarised in the tables. Conclusion This review summarises the application of the LPME procedure and shows the major benefits of LPME, such as the low volume of solvents used, high enrichment factor, simplicity of operation and wide selection of applicable detection techniques. We can expect further development of microextraction analytical methods that focus on direct sample analysis with the application of green extraction solvents while fully automating procedures for the analysis of plant materials.

In recent years, deep eutectic solvents (DES) and it’s mixture with water have become more and more attention as green solvents used in chemistry. However, there are only a few theoretical studies on the mechanisms of pure DES and DES-water complex formation. Therefore, the structural properties of tetrabutylammonium bromide–glycerol-based deep eutectic solvents and their mixtures with water have been investigated by means of Molecular Dynamics simulations. The obtained results indicate that three types of H-bonds exist in the pure DES structures, and all of these interactions play an important role in DES formation. In addition, between hydrogen bond donors (HBDs) and hydrogen bond acceptor (HBA) weaker non-bonded interactions, i.e. van der Waals exist, which also contribute to the formation of stable DES structures and to lower the melting point of DES compared to pure substances. The small addition of water to DES provides the formation of a stable complex, however, a further increase in water content (higher than 50% v/v) provide to the destruction of the most important hydrogen bonds (O–H···Br) in DES structure.

A simple, low-cost, and green cloud point extraction (CPE) procedure was developed for the preconcentration of traces of vanadium as a preliminary step for its spectrophotometric determination. Vanadium(V) was complexed with H2O2 and a novel commercially available reagent, 6-hexyl-4-(2-thiazolylazo)-resorcinol (HTAR), which was preliminary investigated by both theoretical (B3LYP/6-311++G**) and experimental approaches. The ternary complex was then extracted into a small volume of a surfactant-rich phase (Triton X-100). The experimental conditions for total vanadium determination, optimized by the one‐factor‐at‐a‐time method, were found: H2O2 concentration (1.8 × 10−4 mol L−1), HTAR concentration (6.4 × 10−5 mol L−1), acidity (7 × 10−3 mol L−1 H2SO4), mass fraction of the surfactant (2%), incubation time (25 min) and wavelength (582 nm). The linear range, limit of detection, molar absorption coefficient and enrichment factor were calculated to be 2.6–510 ng mL−1, 0.8 ng mL−1, 1.66 × 105 L mol−1 cm−1, and 10.4, respectively. The composition of the extracted complex was V:HTAR:O22− = 1:1:2, which corresponds to a formula [VV(HL)(O2)2], where HL− is the monoprotonated HTAR. The effect of foreign ions was studied, and the accuracy of the proposed procedure was verified by an analysis of an environmental matrix reference material (TM-15.3; Canadian fortified lake water containing 14.2 ng mL−1 of vanadium) and spent silica-supported catalysts. The “greenness” of the developed method was evaluated using the Green Analytical Procedure Index (GAPI).

Deep eutectic solvents (DES) are formed by an acceptor and a donor of hydrogen bonds. They are generally considered as a possible alternative to hazardous organic solvents in various fields. Very recently they have also appeared in analytical chemistry, used mainly for the separation of analytes before instrumental quantification. For the development of new extraction procedures, it is important, among other things, to understand the mechanism of the extraction process itself. In this study we present NMR, IR and Raman spectroscopy studies of TBAB-Gly-based DESs at various HBA:HBD molar ratios for the neat DES as well as the DES mixed with various amounts of added water to better understand the mechanism of DES formation, intermolecular interactions in DES and the interaction of the DES with water, which have not yet been studied in detail. The obtained results indicate that hydrogen bonds between TBAB and Gly exist in the DESs at all molar ratios (1:2; 1:3; 1:4). A small amount of water added to the DES structure provides the establishment of an H-bond network, which does not weaken the existing H-bonds between the HBA and HBD, thus creating a stable supramolecular structure. However, further increasing of water amount provide to weakened of hydrogen bonds between TBAB and Gly.

For the first time an optical probe is proposed as the microdrop holder and simultaneously the measuring cell in a direct immersion single-drop microextraction (DI-SDME) procedure. This approach enables the analytical signal (absorbance of organic phase) to be monitored and recorded online during the extraction process. Based on the suggested approach, a novel on-probe DI-SDME method for the determination of thiocyanate ions using the extraction of the ion pair formed between SCN− and Astra Phloxine reagent in acidic medium into 40 µL of amyl acetate is suggested. The final experimental conditions were found to be: the pH of the aqueous phase being 3, the stirring rate at 500 rpm, a 150 s extraction time, the absorption maximum at 555 nm and 700 nm as the reference wavelength. The calibration plot was linear in the range of 0.29–4.35 mg L−1 of SCN−, with a correlation coefficient of 0.9981. The limit of detection (LOD) was found to be 0.12 mg L−1. The method was applied for analysis of human saliva samples. Furthermore, the possibility of using the optical probe not only for DI-SDME but also for liquid–liquid–liquid microextraction (LLLME) and reverse mode microextraction techniques is shown in separate experiments.

A novel headspace single-drop microextraction method (HS-SDME) for determination of sulfite in the form of sulfur dioxide was developed. An optical probe was used as the droplet holder in the HS-SDME procedure, and the analytical signal (absorbance) was monitored online during the extraction process. The method is based on the conversion of sulfite to volatile sulfur dioxide by acidification of the analyzed solution. The liberated SO2 was absorbed by 25 μL of an aqueous mixed reagent solution placed on the optical probe tip and containing Fe(III), 1,10-phenantroline, and an acetic buffer solution of pH 5.6. During the extraction process, Fe(III) reduces to Fe(II) and the Fe(II) formed then reacts with 1,10-phenantroline to form a colored complex. Absorbance was measured at 510 nm. The calibration plot was linear in the range 0.032–0.320 mg L–1 of sulfite (as SO2), with a correlation coefficient of 0.9989. The limit of detection (LOD), calculated as three times the standard deviation of the blank test (n =...

Novel solvent microextraction techniques are presently receiving a great deal of interest from analytical chemists, as confirmed by the constantly increasing number of published papers on the topic. The present overview offers a comprehensive collection of publications devoted to dispersive liquid–liquid microextraction and dispersive liquid-phase microextraction as well as their modalities. We cover the articles that were available online up to April 30, 2016. The applications of these techniques are summarized in the tables.

Deep eutectic solvents (DES) were introduced as an alternative to ionic liquids (IL) to overcome the drawbacks of IL solvents. However, some authors consider them to be a subclass of ILs. In contrast, other authors emphasize that these are by their nature independent, different groups of substances. Thus, the question arises: Which solvent group should DESs belong to? Maybe a new class should be added to the existing ones. The aim of this work is to attract the attention of researchers using DES in their studies to the need for a proper use of terms.

Deep eutectic solvents are compounds formed by a donor and an acceptor of hydrogen bond; and are in liquid state at ambient temperature. They are non-volatile, with high thermal stability and readily dissolve many organic and inorganic compounds. They are recognized as green and cheap alternatives to ionic liquids. They have recently appeared in analytical practice but have already found wide application in various fields of analytical chemistry; mainly as effective extractants. However, their use as extractants does not limit the scope of their capabilities. This review is primarily devoted to the description of new possibilities of applications of deep eutectic solvents in analytical chemistry; including such areas as chromatographic separation, electrochemical analysis, sample preparation, synthesis and modification of new sorption materials. In addition, the stability of deep eutectic solvents, terminology, classification, further trends and some errors and inaccuracies associated with their applications are discussed.

Deep eutectic solvents (DESs) are currently being used in different sectors, such as electrochemistry, electrodeposition, organic synthesis, nanoparticle preparation, bioactive compound separation, etc. Their use in analytical chemistry has only recently begun to expand. Despite the publication of a sufficient number of DES-based analytical extraction procedures, some details, such as interaction of DES with the sample and target analytes as well as with water are insufficiently explored and theoretically explained. Here we discuss the role of water in DES-based extraction in terms of analytical chemistry, especially for the pre-treatment of solid samples. We believe that this review will benefit those who have linked their research with DESs and will enable them to speed up their work.

A novel fluidized beads strategy for utilization of particle-immobilized reagents in flow analysis was developed in this study. The performance of the suggested strategy was demonstrated by the determination of glycerol in biodiesel. This analytical task was used as a proof-of-concept example. The method is based on on-line extraction of glycerol from biodiesel into aqueous stationary phase of extraction-chromatographic column, followed by elution and spectrophotometric determination in the form of copper glycerate formed in a fluidized reactor of stepwise injection system. The floating of cation exchange resin Dowex(®) 50WX4, saturated with Cu(II) ions in liquid phase, was accomplished by air-bubbling. The linear range was from 100 to 1000 mg kg(-1), and the limit of detection, calculated as 3s of a blank test (n = 5), was found to be 30 mg kg(-1). The method was successfully applied to the analysis of biodiesel and biodiesel-blend (B 20) samples.

A novel vortex-assisted liquid-liquid microextraction (VA-LLME) for determination of iodide was developed. The method includes the oxidation of iodide with iodate in the presence of hydrochloric acid followed by VA-LLME of the ion-pair formed between ICl2(-) and Astra Phloxine reagent (AP) and subsequent absorbance measurement at 555nm. The appropriate experimental conditions were investigated and found to be: 5mL of sample, 0.27molL(-)(1) HCl, 0.027mmolL(-1) KIO3 as the oxidation agent, 250μL of extraction mixture containing amyl acetate as the extraction solvent and carbon tetrachloride as the auxiliary solvent (1:1, v/v), 0.04mmolL(-1) AP reagent, vortex time: 20s at 3000rpm, centrifugation: 4min at 3000rpm. The calibration plot was linear in the range 16.9-169μg L(-1) of iodide, with a correlation coefficient (R(2)) of 0.996, and the relative standard deviation ranged from 1.9 to 5.7%. The limit of detection (LOD) and limit of quantification (LOQ) were 1.75 and 6.01μgL(-)(1) of iodide, respectively. The suggested procedure was applied for determination of iodide in real mineral water samples.

A novel method for the determination of mercury(II) is suggested. The procedure is based on the formation of an ion associate between the bromide complex of Hg(II) and Astrazon Red 6B dye and vortex-assisted liquid-liquid microextraction of the ion associate formed, with subsequent spectrophotometric detection. The variables that affect the procedure, such as pH, the concentration of ligand and dye, the type and volume of extraction solvent, and the rate and time of vortex mixing, were optimized. Under optimum conditions (pH 2.0, 0.01 mol L$^{-1}$ KBr, 2 $\times $ 10$^{-4}$ mol L$^{-1}$ AR6B, 50 $\mu $L of the extraction mixture toluene:dichlorethane, 4:1, v:v, vortex mixing for 100 s~at 1600 rpm) the linear range was 8 to 200 $\mu $g L$^{-1}$ Hg(II), with the limit of detection at 1.5 $\mu $g L$^{-1}$. The method was applied to the determination of mercury in water samples.

A first attempt to automate the effervescence assisted dispersive liquid-liquid microextraction (EA-DLLME) has been reported. The method is based on the aspiration of a sample and all required aqueous reagents into the stepwise injection analysis (SWIA) manifold, followed by simultaneous counterflow injection of the extraction solvent (dichloromethane), the mixture of the effervescence agent (0.5 mol L(-1) Na2CO3) and the proton donor solution (1 mol L(-1) CH3COOH). Formation of carbon dioxide microbubbles generated in situ leads to the dispersion of the extraction solvent in the whole aqueous sample and extraction of the analyte into organic phase. Unlike the conventional DLLME, in the case of EA-DLLME, the addition of dispersive solvent, as well as, time consuming centrifugation step for disruption of the cloudy state is avoided. The phase separation was achieved by gentle bubbling of nitrogen stream (2 mL min(-1) during 2 min). The performance of the suggested approach is demonstrated by determination of antipyrine in saliva samples. The procedure is based on the derivatization of antipyrine by nitrite-ion followed by EA-DLLME of 4-nitrosoantipyrine and subsequent UV-Vis detection using SWIA manifold. The absorbance of the yellow-colored extract at the wavelength of 345 nm obeys Beer's law in the range of 1.5-100 µmol L(-1) of antipyrine in saliva. The LOD, calculated from a blank test based on 3σ, was 0.5 µmol L(-1).

A novel dispersive liquid–liquid microextraction based on solidification of a floating organic drop (DLLME-SFO) for determination of orthophosphate was developed. The method includes the formation of molybdoantimonatophosphoric heteropoly blue (HPB) followed by a DLLME-SFO procedure and subsequent absorbance measurement using a micro volume cell (5 μL) with 10 mm path length. The final experimental conditions for HPB extraction were found to be: 0.6 mL of ethanol as dispersive solvent containing 55 μL of 1-undecanol as extraction solvent, magnetic stirring at 500 rpm, 10 min extraction time, decreasing the stirring rate to 150 rpm in order to group all the droplets and then solidification of the organic droplet in an ice bath for 5 min under continuous magnetic stirring. It should be pointed out that no centrifugation step is required. The calibration plot was linear in the range 4.0–60 × 10 − 8 mol L − 1 of phosphate, with a correlation coefficient of 0.9982. The limit of detection (LOD), calculated as three times the standard deviation of the blank test (n = 10), was 7.4 × 10 − 9 mol L − 1 of phosphate. The reported procedure was applied for determination of phosphate in real water samples.

The infrared and Raman spectra of dehydroacetic acid and some of its derivatives were measured. The assignments of the vibrational bands were based on quantum chemical calculations and normal coordinate analysis. The optimized structures, atomic net charges and dipole moments of the investigated molecules were also results of our quantum chemical calculations. The analysis of the last properties made possible a deeper insight into the structure and substituent effect on the investigated molecules. One of them is presented in the graphical abstract.

We give an overview of achievements in solidified floating organic drop microextraction (SFODME). We focus on the types of analyte investigated, the types of sample analyzed, the sample-pre-treatment procedures used, including derivatization and complexation, and we cover the articles available on-line up to 30 November 2014. SFODME has been applied to the determination of organic compounds and inorganic analytes. Although most extraction methods based on SFODME have been applied to water samples, the technique has also been used for analysis of other types of samples. We also briefly discuss the effects of different variables. We discuss the various modalities of SFDOME. Tables summarize the applications, selected experimental conditions and the most important parameters of SFODME.

The literature on dispersive solvent microextraction comprises a great many methodologies, different possibilities and a broad range of terminology, all of which greatly complicates the classification of these methods as well as the conditions to be specified in the procedure name, its acronym or both. Our view on the current status of this issue is presented with the goal of standardizing and simplifying the terminology.

A novel and simple procedure for determination of anionic surfactants has been developed. The method is based on the reaction of sodium dodecyl sulphate (SDS) with Astra Phloxine FF reagent at pH 3–8, followed by liquid–liquid microextraction of the formed ion associate into an organic phase containing a mixture of carbon tetrachloride and dichloroethane (4:1, v/v) and subsequent UV-Vis detection at 555 nm. The calibration plot was linear in the range 0.006–0.29 mg L−1 of SDS. The limit of detection (LOD), calculated based on 3s, is 0.002 mg L−1. The method was applied to the determination of anionic surfactants in real wastewater samples.