Ultrasound-assisted ionic liquid/ionic liquid-dispersive liquid–liquid microextraction for the determination of sulfonamides in infant formula milk powder using high-performance liquid chromatography

In-syringe low-density solvent dispersive liquid-liquid microextraction of Pd(II) from acidic solutions resulting from hydrometallurgical treatments and quantification by ICP-OES

An in-syringe low-density solvent dispersive liquid-liquid microextraction (IS-LDS-DLLME) is presented for the extraction of palladium from a highly acidic medium before its quantification by inductively coupled plasma optical emission spectroscopy. The extraction solvent was 1-undecanol, and benzil mono-(2-pyridyl) hydrazone was employed as a ligand. Here, no dispersive solvent is needed as the vortex disperses 1-undecanol in the aqueous sample solution. The experimental variables pH, concentration of the ligand, type and quantity of the extraction solvent, vortex time, and addition of NaCl were optimized. The described approach has detection and quantification limits of 0.13 and 0.43 μg L-1, respectively, an enrichment factor of 91, a linear analytical range from 0.4 to 250 μg L-1, and a precision of 1.7-2.0 % (25.0 μg L-1). The approach was used to analyze electronic waste samples and certified reference material.

Ultrasonic assisted magnetic solid phase extraction of ultra-trace mercury with ionic liquid functionalized materials

Due to the agglomeration between particles, the inherent adsorption characteristics of magnetic powder materials are usually difficult to fully display. Taking ionic liquid functional materials as an example, the enrichment behavior of these adsorbents for trace mercury (Hg²⁺) in ultrasonic (US) assisted dispersion mode was systematically studied. The dissociation of protonic ionic liquids (IL) occur in the process of dispersion and the strong electrostatic attraction can improve the diffusion and adhesion of mercury on the adsorbent surface. Spectral measurement data showed that with the help of US, the more uniform dispersion of magnetic materials accelerated the adsorption of trace Hg²⁺. Ultrasonic intrinsic parameters such as frequency, power and radiation duration significantly affect the dispersion and apparent adsorption properties of magnetic functional materials. In the range of experimental parameters, the dye/paper image experimental results documents that there is a positive correlation between cavitation effect and ultrasonic frequency/power. The enrichment degree of fixed adsorbate (0.1 μg L^-1) under high frequency (59 kHz) or high-power input (100%) is 1-2 times higher than that under low frequency (40 kHz) or low power (60%) input. This is a valuable conclusion for the subsequent study of US dispersion of magnetic and even non-magnetic powder materials. In addition, the in-situ desorption and accurate measurement of adsorbed mercury were realized by combining slurry vapor generation atomic fluorescence spectroscopy (SVG-AFS). The constructed US assisted magnetic solid phase extraction (US-MSPE) method has the characteristics of low detection limit (0.36 ng L^-1), high recovery (>90%), sustainable utilization (>3) and reasonable measurement deviation (<5%), which can meet the requirements of ultra-trace Hg²⁺ (0.01-1.0 μg L^-1).

Green vortex-assisted emulsification microextraction using a ternary deep eutectic solvent for extraction of tetracyclines in infant formulas

A novel green alternative vortex-assisted emulsification liquid-liquid microextraction based on a new hydrophobic deep eutectic solvent (DES) was developed to extract tetracyclines in infant formulas. Five new ternary DESs were synthesized and tested in this regard. Among them [thymol]:[ethylene glycol]:[benzyl alcohol] (2:2:1) DES demonstrated the highest extraction efficiency. The analyzes were performed by HPLC. The DES was characterized by attenuated total reflectance-FTIR, nuclear magnetic resonance spectroscopy, and octanol-water partition coefficient. The effect of type, mole ratio, and volume of DES, dispersing agent, pH, and ionic strength was studied. The limits of quantification and linear range were 3-9.32 and 3-500 μg kg^-1, respectively. The method was applied to detect tetracyclines in infant formulas, and the recoveries were obtained as 68.9-102.0 % with relative standard deviations < 9 %. The procedure greenness was assessed using the Analytical Eco-Scale. This paper represents the first application of a novel ternary DES to analyze tetracyclines in infant formulas.

Ionic Liquid-Assisted DLLME and SPME for the Determination of Contaminants in Food Samples

Developing effective and green methods for food analysis and separation has become an urgent issue regarding the ever-increasing concern of food quality and safety. Ionic liquids (ILs) are a new chemical medium and soft functional material developed under the framework of green chemistry and possess many unique properties, such as low melting points, low-to-negligible vapor pressures, excellent solubility, structural designability and high thermal stability. Combining ILs with extraction techniques not only takes advantage of ILs but also overcomes the disadvantages of traditional extraction methods. This subject has attracted intensive research efforts recently. Here, we present a brief review of the current research status and latest developments regarding the application of IL-assisted microextraction, including dispersive liquid–liquid microextraction (DLLME) and solid-phase microextraction (SPME), in food analysis and separation. The practical applications of ILs in determining toxic and harmful substances in food specimens with quite different natures are summarized and discussed. The critical function of ILs and the advantages of IL-based microextraction techniques over conventional extraction techniques are discussed in detail. Additionally, the recovery of ILs using different approaches is also presented to comply with green analytical chemistry requirements.

Surface-Active Ionic Liquid-Assisted Cloud Point Extraction for Pre-Concentration and Determination of Cobalt Ions in Pharmaceutical Preparations

: Herein we describe an efficient, simple, and precise micelle-mediated microextraction strategy based on the aggregation behavior of surface-active ionic liquids (SAILs) for the preconcentration and determination of cobalt ions in pharmaceutical preparations. Unlike the commonly used hydrophobic ionic liquids in IL-based microextraction methods, a water-soluble surface-active ionic liquid [1-hexadecyl 3-methylimidazolium chloride (C16MeImCl)] was used. A modified cloud point extraction (CPE) procedure based on the C16MeImCl-Triton X-114 mixed micellar system was proposed as an efficient extracting phase. A comparison of the analytical features of the extraction process with and without SAILs revealed the benefits of the proposed method. Advantages such as a wider linear range, lower detection limit, higher reproducibility, and improved extraction efficiency highlighted the proposed method over the conventional CPE method. These attractive specifications are due to the higher extraction efficiencies achieved in the presence of the SAIL and its favorable effects at the phase separation stage. Various parameters affecting the extraction efficiency were optimized by univariate and multivariate (Box-Behnken design) approaches. The calibration curve was obtained in the optimal experimental conditions with a linear range from 0.01 to 5.5 mg L-1 of cobalt ion concentration (R = 0.9992) and a detection limit of about 0.005 mg L-1. The RSD% for 10 replicate determinations of 1.0 mg L-1 Co was 0.9%. The proposed method was successfully applied to determine cobalt ions in vitamin B12 ampoules and tablets.

In-syringe dispersive liquid-liquid microextraction

Dispersive liquid-liquid microextraction (DLLME) has recently been widely used in the separation and preconcentration of various chemical species. Among the various approaches using DLLME are systems that use a syringe as an extraction environment. In this review, details of some methods that use this approach are presented. The ways to promote dispersion, analytical characteristics, and the advantages and disadvantages of the methods, among other aspects, are discussed critically. Finally, some trends in the use of in-syringe microextraction systems are described.

β-Cyclodextrin-/AuNPs-functionalized covalent organic framework-based magnetic sorbent for solid phase extraction and determination of sulfonamides

β-Cyclodextrin-functionalized magnetic covalent organic framework (Fe₃O₄@COF@Au-β-CD) was developed as sorbent for magnetic solid phase extraction of trace sulfonamides in meat samples prior to HPLC-MS/MS analysis. The sorbent was synthesized by loading gold nanoparticles onto a Fe₃O₄@COF surface and then functionalized by thiolated-β-cyclodextrin immobilization via Au-S bonding formation. The prepared composite material was employed for sulfonamides extraction. The main parameters were optimized to obtain the best extraction efficiency. The experiments of adsorption kinetics were carried out to investigate the adsorption mechanism. Results showed the pseudo-second-order kinetic was better fitted with the adsorption kinetics of sulfonamides. Under optimized conditions, the magnetic solid phase extraction-HPLC method showed good linearity (R² ≥ 0.9936), and the limits of detection were in the range of 0.8-1.6 μg kg^-1. The proposed method was successfully used for quantitation of sulfonamides in real samples. The recoveries ranged from 78.9 to 112.0% with relative standard deviations (RSDs) < 10% (n = 5). The proposed method exhibited great potential for enrichment and determination of sulfonamides in many other food or environment samples. Graphical abstract.

State-of-the-art on the technique of dispersive liquid-liquid microextraction

Dispersive liquid-liquid microextraction is a new sample pretreatment technology based on traditional liquid liquid extraction. In this paper, the application of low-toxicity extractants such as low-density extractants, auxiliary extractants, stripping agents and ionic liquids in this technology and the extraction modes such as solvent de-emulsification, suspension extractant curing, auxiliary extraction, back extraction, and ionic liquid-dispersion liquid microextraction, are summarized. In addition, the synergism of this technique with other sample preparation techniques, such as liquid-liquid extraction, solid-phase extraction, solid-phase microextraction, dispersive solid phase extraction, matrix solid-phase dispersion extraction, supercritical fluid extraction and ultrasound-assisted dispersive liquid-liquid microextraction is discussed.

Trends in Microextraction-Based Methods for the Determination of Sulfonamides in Milk

Sulfonamides (SAs) represent a significant category of pharmaceutical compounds due to their effective antimicrobial characteristics. SAs were the first antibiotics to be used in clinical medicine to treat a majority of diseases, since the 1900s. In the dairy farming industry, sulfa drugs are administered to prevent infection, in several countries. This increases the possibility that residual drugs could pass through milk consumption even at low levels. These traces of SAs will be detected and quantified in milk. Therefore, microextraction techniques must be developed to quantify antibiotic residues, taking into consideration the terms of Green Analytical Chemistry as well.

Development of a novel naphthoic acid ionic liquid and its application in "no-organic solvent microextraction" for determination of triclosan and methyltriclosan in human fluids and the method optimization by central composite design

In traditional ionic liquids (ILs)-based microextraction, the hydrophobic and hydrophilic ILs are often used as extractant and disperser, respectively. However, the functional effects of ILs are not utilized in microextraction procedures. Herein, we introduced 1-naphthoic acid into imidazolium ring to synthesize a novel ionic liquid 1-butyl-3-methylimidazolium naphthoic acid salt ([C4MIM][NPA]), and its structure was characterized by IR, (1)H NMR and MS. On the basis of its acidic property and lower solubility than common [CnMIM][BF4], it was used as a mixing dispersive solvent with [C4MIM][BF4] in "functionalized ionic liquid-based no organic solvent microextraction (FIL-NOSM)". Utilization of [C4MIM][NPA] in FIL-NOSM procedures has two obvious advantages: (1) it promoted the non-polar environment, increased volume of the sedimented phase, and thus could enhance the extraction recoveries of triclosan (TCS) and methyltriclosan (MTCS) by more than 10%; and (2) because of the acidic property, it can act as a pH modifier, avoiding extra pH adjustment step. By combining single factor optimization and central composite design, the main factors in the FIL-NOSM method were optimized. Under the optimal conditions, the relative recoveries of TCS and MTCS reached up to 98.60-106.09%, and the LODs of them were as low as 0.12-0.15µgL(-1) in plasma and urine samples. In total, this [C4MIM][NPA]-based FIL-NOSM method provided high extraction efficiency, and required less pretreatment time and unutilized any organic solvent. To the best of our knowledge, this is the first application of [C4mim][NPA]-based microextraction method for the simultaneous quantification of trace TCS and MTCS in human fluids.

Dispersive Liquid-Liquid Microextraction in the Analysis of Milk and Dairy Products: A Review

Dispersive liquid-liquid microextraction (DLLME) is an extraction technique developed within the last decade, which involves the dispersion of fine droplets of extraction solvent in an aqueous sample. Partitioning of analytes into the extraction phase is instantaneous due to the very high collective surface area of the droplets. This leads to very high enrichment factors and very low solvent consumption, relative to other liquid or solid phase extraction methods. A comprehensive review of the various modes of DLLME in the analysis of organic and inorganic analytes in dairy products (milk, cheese, infant formula, yogurt, and breast milk) is presented here. Dairy products present a complex sample matrix and the removal of interfering matrix components can prove troublesome. This review focuses on sample pretreatment prior to the appropriate DLLME procedure, the extraction and dispersive solvents chosen, derivatisation methods, and analytical figures of merit. Where possible, a critical comparison of DLLME methods has been undertaken. The overall suitability, and limitations, of DLLME as a sample preparation technique for dairy products has been assessed.

Environmental Application, Fate, Effects, and Concerns of Ionic Liquids: A Review

Ionic liquids (ILs) comprise mostly of organic salts with negligible vapor pressure and low flammability that are proposed as replacements for volatile solvents. ILs have been promoted as "green" solvents and widely investigated for their various applications. Although the utility of these chemicals is unquestionable, their toxic effects have attracted great attention. In order to manage their potential hazards and design environmentally benign ILs, understanding their environmental behavior, fate and effects is important. In this review, environmentally relevant issues of ILs, including their environmental application, environmental behavior and toxicity are addressed. In addition, also presented are the influence of ILs on the environmental fate and toxicity of other coexisting contaminants, important routes for designing nontoxic ILs and the techniques that might be adopted for the removal of ILs.

A sensitive emulsification liquid phase microextraction coupled with on-line phase separation followed by HPLC for trace determination of sulfonamides in water samples

For the first time, ion-pair based emulsification liquid phase microextraction coupled with a novel approach for phase separation followed by high performace liquid chromatgraphy (HPLC) was utilized for trace determination of sulfonamides in water samples. After the formation of ion-pair complex with a cationic surfactant, sulfonamides were extracted into the drops of dispersed organic extracting solvent. Then, the cloudy solution was passed through an in-line filter located in a suitable holder and was separated based on emulsion filtration. By changing the HPLC valve position, the filter was laid in the mobile phase path, and the extraction phase was eluted by the mobile phase and introduced into the separation column for analysis. The effects of important parameters, such as type of extraction solvent, type of ion-pair agent and its concentration, pH of sample solution, ionic strength, and volume of extraction phase, on the extraction efficiency, were investigated and optimized. Under optimal conditions, the linear range, limits of detection, and precision (relative standard deviations) were 0.3-100, 0.1-0.3 μg L(-1), and 4.7-5.8%, respectively. Preconcentration factors (PFs) for the compounds studied were obtained in the range of 268-664. These PFs correspond to extraction recoveries in the range of 41-97%. The sample throughput of the method was 3 samples per hour, regarding 20 min analysis time for a single procedure. Finally, the method was successfully applied to determine the selected sulfonamides in some water samples.

Determination of sulfonamide antibiotics and metabolites in liver, muscle and kidney samples by pressurized liquid extraction or ultrasound-assisted extraction followed by liquid chromatography-quadrupole linear ion trap-tandem mass spectrometry (HPLC-QqLIT-MS/MS)

Sulfonamides are widely used in human and veterinary medicine. The presence of sulfonamides residues in food is an issue of great concern. Throughout the present work, a method for the targeted analysis of 16 sulfonamides and metabolites residue in liver of several species has been developed and validated. Extraction and clean-up has been statistically optimized using central composite design experiments. Two extraction methods have been developed, validated and compared: i) pressurized liquid extraction, in which samples were defatted with hexane and subsequently extracted with acetonitrile and ii) ultrasound-assisted extraction with acetonitrile and further liquid-liquid extraction with hexane. Extracts have been analyzed by liquid chromatography-quadrupole linear ion trap-tandem mass spectrometry. Validation procedure has been based on the Commission Decision 2002/657/EC and included the assessment of parameters such as decision limit (CCα), detection capability (CCβ), sensitivity, selectivity, accuracy and precision. Method׳s performance has been satisfactory, with CCα values within the range of 111.2-161.4 µg kg(-1), limits of detection of 10 µg kg(-1) and accuracy values around 100% for all compounds.