Sorbent Research Articles

Fine-Tuning Microporosity of Crystalline Vanadomolybdate Frameworks for Selective Adsorptive Separation of Kr from Xe.

Selective adsorptive capture and separation of chemically inert krypton (Kr) and xenon (Xe) noble gases with very low ppmv concentrations in air and industrial off-gases constitute an important technological challenge. Here, using a synergistic combination of experiment and theory, the microporous crystalline vanadomolybdates (MoVOx) as highly selective Kr sorbents are studied in detail. By varying the Mo/V ratios, we show for the first time that their one-dimensional (1D) pores can be fine-tuned for the size-selective adsorption of Kr over the larger Xe with selectivities reaching >100. Using extensive electronic structure calculations and grand canonical Monte Carlo simulations, the competition between Kr uptake with CO2 and N2 was also investigated. As most materials reported so far are selective toward the larger, more polarizable Xe than Kr, this work constitutes an important step toward robust Kr-selective sorbent materials. This work highlights the potential use of porous crystalline transition metal oxides as energy-efficient and selective noble gas capture sorbents for industrial applications.

Alternate materials for the capture and quantification of gaseous oxidized mercury in the atmosphere

Abstract. Methodologies for identifying atmospheric oxidized mercury (HgII) compounds, including particulate-bound HgII (HgII(p)) and gaseous oxidized mercury (HgII(g)), by mass spectrometry are currently under development. This method requires preconcentration of HgII for analysis due to high instrument detection limits relative to ambient HgII concentrations. The objective of this work was to identify and test materials for quantitative capture of HgII from the gas phase and to suggest potential surfaces onto which HgII can be collected, thermally desorbed, and characterized using mass spectrometry methods. From the literature, several compounds were identified as potential sorbent materials and tested in the laboratory for uptake of gaseous elemental mercury (Hg0) and HgII(g) (permeated from a HgBr2 salt source). Chitosan, α-Al2O3, and γ-Al2O3 demonstrated HgII(g) capture in ambient air laboratory tests, without sorbing Hg0 under the same conditions. When compared to cation exchange membranes (CEMs), chitosan captured a comparable quantity of HgII(g), while ≤90 % of loaded HgII(g) was recovered from α-Al2O3 and γ-Al2O3. When deployed in the field, the capture efficiency of chitosan decreased compared to CEMs, indicating that environmental conditions impacted the sorption efficiency of this material. The poor recovery of HgII from the tested materials compared to CEMs in the field indicates that further identification and exploration of alternative sorbent materials are required to advance atmospheric mercury chemistry analysis by mass spectrometry methods.

Application of coniferous bark as sorbent material for per- and polyfluoroalkyl substances – A case study in Sweden

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic contaminants commonly found in drainage water from waste management facilities. Within the European Union, these facilities either treat the water locally or transfer it to wastewater treatment plants to reduce harmful emissions. However, PFAS are a broad class of compounds with varying physicochemical properties, leading to different removal efficiencies for adsorbents. Activated carbon and ion exchange resins are effective but costly, and they can become saturated with other contaminants. Therefore, this study aims to explore inexpensive, abundant alternatives for reducing PFAS concentrations in the environment. In Sweden, bark is a by-product of forestry activities, primarily used as fuel in heat and power plants. This study evaluates the ability of pine and spruce bark to remove PFAS from contaminated drainage water. Initial laboratory experiments employed liquid-to-solid ratios of 10 and 20 to assess the performance of both materials. Results indicated that pine bark exhibited better removal efficiencies, particularly when a layered column with pine bark followed by spruce bark was utilized. The overall removal efficiencies for short-chain PFAS (perfluorinated carbons: PFCA C3–C6 and PFSA C4–C5) and long-chain PFAS (PFCA > C7 and PFSA > C6) were below 20%, except for perfluorooctane sulfonic acid (PFOS), which showed reductions of 40%–80%. The pH of the treated water decreased from 7 to 4 (pine bark) and 5 (spruce bark) after treatment. In a larger-scale trial, a combination of 50% pine bark and 50% spruce bark was tested, achieving similar reductions for PFOS. Although the removal efficiencies were insufficient for exclusive treatment, these materials may be useful in specific applications targeting long-chain PFAS or in conjunction with other treatment methods.

Silica-Based Composite Sorbents for Heavy Metal Ions Removal from Aqueous Solutions.

Weak polyelectrolyte chains are versatile polymeric materials due to the large number of functional groups that can be used in different environmental applications. Herein, one weak polycation (polyethyleneimine, PEI) and two polyanions (poly(acrylic acid), PAA, and poly(sodium methacrylate), PMAA) were directly deposited through precipitation of an inter-polyelectrolyte coacervate onto the silica surface (IS), followed by glutaraldehyde (GA) crosslinking and extraction of polyanions chains. Four core-shell composites based on silica were synthesized and tested for adsorption of lead (Pb2+) and nickel (Ni2+) as model pollutants in batch sorption experiments on the laboratory scale. The sorbed/desorbed amounts depended on the crosslinking degree of the composite shell, as well as on the type of anionic polyelectrolyte. After multiple loading/release cycles of the heavy metal ions, the maximum sorption capacities were situated between 5-10 mg Pb2+/g composite and 1-6 mg Ni2+/g composite. The strong crosslinked composites (r = 1.0) exhibited higher amounts of heavy metal ions (Me2+) sorbed than the less crosslinked ones, with less PEI on the surface but with more flexible chains being more efficient than more PEI with less flexible chains. Core-shell composites based on silica and weak polyelectrolytes could act as sorbent materials, which may be used in water or wastewater treatment.

An ionic liquid-based adjuvant for modulating cellular and humoral immune responses

Vaccination is an important strategy for the prevention of infectious diseases worldwide. Adjuvants can be incorporated in vaccine formulations to enhance the resultant immune response and subsequently confer more robust protection upon natural infection. While adjuvants have exciting potential to improve vaccination, the landscape of materials employed in clinical adjuvants is small and its expansion is needed to facilitate vaccine development against current and future infectious diseases. This study introduces the first ionic liquid (IL) adjuvant comprised of choline and sorbic acid (ChoSorb) to produce an antigen-specific cellular as well as humoral immune response against multiple antigens. The abilities of ChoSorb as a vaccine adjuvant is evaluated and characterized through material analysis, innate immune responses, and adaptive responses to both a model and clinical grade antigen. With the robust immune responses generated by ChoSorb and the accompanying mechanistic insights, this study introduces ILs as a new class of adjuvant materials for future vaccine design.

New Insights into the Structure, Thermal Properties, and Photostability of Industrially Relevant Salts of Sorbic Acid

New Insights into the Structure, Thermal Properties, and Photostability of Industrially Relevant Salts of Sorbic Acid

Boosting uranium extraction from Seawater by micro-redox reactors anchored in a seaweed-like adsorbent

Efficient extraction of uranium from seawater is expected to provide virtually infinite fuel sources to power nuclear reactors and thus enable sustainable development of nuclear energy. The extraction efficiency for uranium greatly depends on the availability of active adsorption sites on the adsorbents. Maximization of the utilization rate of the binding sites in the adsorbent is vital for improving adsorption capacity. Herein, micro-redox reactors functioned by Cu(I)/Cu(II) conversion are constructed internally in an adsorbent bearing both amidoxime and carboxyl groups to induce active regeneration of the inactivated binding sites to enhance uranium capture. This adsorbent has high adsorption capacity (962.40 mg-U/g-Ads), superior anti-fouling ability as well as excellent uranium uptake (14.62 mg-U/g-Ads) in natural seawater after 56 days, placing it at the top of high-performance sorbent materials for uranium harvest from seawater.

Antifungal effects of three natural branched medium-chain fatty acids and their potential as fumigants against Aspergillus flavus in stored peanut seeds

The contamination of peanuts with aflatoxins predominantly produced by Aspergillus flavus poses a worldwide threat to both food safety and agricultural economies. Antifungal compounds from natural sources may offer a safe and effective alternative strategy to control A. flavus in peanuts. We evaluated the contact and fumigant antifungal effects of three natural branched medium-chain fatty acids (branched-MCFAs), (E)-2-methyl-2-pentenoic acid, 2-methylhexanoic acid, and 2-methylheptanoic acid against A. flavus relative to their straight-chain isomers and sorbic acid a commonly used preservative. In vitro experiments showed that the inhibitory effects of these three branched-MCFAs on A. flavus were stronger than their straight-chain isomers and sorbic acid. In addition, fumigant effects of the branched-MCFAs were more effective than their direct contact inhibitory effects against the growth of A. flavus. 2-Methylhexanoic acid, 2-methylheptanoic acid, and (E)-2-methyl-2-pentenoic acid showed significant fumigant activity, with the minimum inhibitory concentration (MIC) values of 0.10, 0.10, and 0.12 g/l air, respectively. Fumigation of these branched-MCFAs also significantly slowed the growth of A. flavus in peanut seeds, and completely inhibited A. flavus growth at 2.0 g/l air. After 24 h of fumigation exposure to the branched-MCFAs, the fumigated A. flavus on medium or peanut seeds was re-incubated to observe whether the A. flavus could continue to grow, and the results revealed that the in vitro and in vivo minimum fungicidal concentrations (MFC) were 0.15 and 2.5 g/l air, respectively. This study indicated that these three natural branched-MCFAs have strong antifungal fumigation activity with application potential in protecting peanut seeds from A. flavus contamination during storage.

Carrageenan-Reduced Silver Nanoparticles for Direct and Rapid SERS Detection of Sorbic Acid

Carrageenan-Reduced Silver Nanoparticles for Direct and Rapid SERS Detection of Sorbic Acid

Development of free flowing granular hybrid functionalized clay sorbent filters for chromium removal from waste water

Chromium (VI) contamination in water resources at industrial sites poses significant environmental and health risks. Conventional sorbents often suffer from limitations such as clogging, back pressure, poor kinetics, and challenges in coupling with flow systems and regeneration. This study focuses on developing, characterizing, and applying free-flowing granular (FFG) amidoxime-functionalized montmorillonite (Mt) clay sorbents (AO-Mt-H-C) to enhance chromium (VI) removal from contaminated waste water. Batch adsorption experiments demonstrated that AO-Mt-H-C outperformed montmorillonite clay modified with quaternary ammonium alone (Mt-H-C), achieving a Cr (VI) removal efficiency of 50.6 mg g−1 compared to 44.3 mg g−1, due to the synergistic interactions of quaternary ammonium and amidoxime functionalities. To address the limitations of conventional sorbents, such as clogging and poor kinetics, an FFG filter column was developed and tested, showing effective Cr (VI) removal across various water sources with minimal interference in drinking and groundwater. In industrial wastewater with higher matrix loads, over 99 % removal efficiency was achieved with a 25 % increase in sorbent dosage. Desorption and reusability assessments confirmed the AO-Mt-H-C's effectiveness across three cycles. Mathematical modelling using Thomas and Yoon–Nelson equations supported the design of customized treatment systems. Scalability was demonstrated by treating 1.6 m3 of textile industrial effluents (100 mg L−1 Cr (VI)) with quantitative removal efficiency (>99.5 %). This study illustrates that the hybrid functionalization and free-flowing granulation of clay sorbent materials significantly enhance Cr (VI) removal, providing valuable insights for advanced water pollution mitigation and environmental sustainability.

Palatability of organic acids and their derivatives for cichlid fishes (Cichlidae)

Taste attractivity of 15 organic acids and their derivatives (ascorbic, citric, sorbic, malic, oxalic, acetic, glycolic, α- and γ-aminobutyric acids, their Na+- and K+-salts; 0,1 M) was compared for 5 species of cichlid fishes (Cichlidae) – Nile Oreochromis niloticus and Mozambique O. mossambicus tilapias, golden mbuna Melanochromis auratus, lemon cichlid Neolamprologus leleupi and tailbar cichlid Vieja hartwegi. Citric and oxalic acids, Na+-ascorbate, K+-sorbate and K+-citrate, ammonium oxalate have an attractive or indifferent taste for fish, ascorbic and sorbic acids, Na+-citrate and Na+-malate have an aversive or indifferent taste. Malic acid has an attractive taste for tailbar cichlid, an aversive taste for Mozambique tilapia and an indifferent taste for other cichlids. Acetic acid and isomers of aminobutyric acid have indifferent taste for all fishes. The taste attractivity of organic acids may be different compared to salts formed on their basis. The attractiveness of salts is higher than that of the corresponding acids in 10 out of 28 cases, lower in 4 cases, and the same in 14 cases. The conversion of ascorbic and sorbic acids into Na+ and K+ salts is accompanied by an increase in taste attractivity in most cichlids, malic acid to malate Na+ – in half of the species. For most fish, citric acid and its Na+- and K+-salts have similar attractiveness. Oxalic acid, compared with ammonium oxalate, has a higher attractiveness for lemon cichlid, a lower one for Mozambique tilapia and the same taste quality for the other three fish species. There are no differences between the consumption of agar pellets with isomers of aminobutyric acid and pellets with acetic and glycolic (hydroxy acetic) acids in all cichlids. The feeding behavior shown by cichlids during the orosensory testing of pellets is similar – fish perform a small number of rejections and repeated grasps of pellets, the duration of pellet retention time in the oral cavity is similar.

Determination of naturally derived propionic, benzoic, and sorbic acids in seafood, meats, and fruits during storage

Propionic acid, benzoic acid, and sorbic acid are common preservatives in processed foods, but their natural concentrations in raw foods are not well understood. In Korea, if propionic acid or benzoic acid exceeds certain levels in processed plant-based foods, manufacturers must prove they are naturally occurring to avoid recalls. This regulation applies to both local and imported products, with non-compliance leading to economic costs and damage to brand reputation. To address this, further research is needed to build a database of naturally occurring preservatives in raw foods and develop food safety standards. This study quantified the levels of propionic, benzoic, and sorbic acids in 37 raw foods stored at different temperatures for 2 weeks, using gas chromatography and high-performance liquid chromatography. The changes in acid concentrations during storage were examined, with preservatives identified by mass spectrometry. Sensory evaluation and total viable count were used to assess spoilage in seafood and meat samples. The matrix effects were evaluated, and the quantification methods were validated using seven food matrices. The intra- and interday accuracies and precisions (% relative standard deviation, %RSD) values met the Codex guidelines. In general, the propionic acid contents of most seafood and meat samples increased during storage, with the highest content being found in manila clams. Interestingly, the fresh sea squirt sample contained a higher propionic acid content (456mg/kg) than the other samples. However, benzoic acid and sorbic acid were not detected in most samples, with the exception of the jujube and apple samples.

Interactions between antibiotic removal, water matrix characteristics and layered double hydroxide sorbent material

Sorption by layered double hydroxides (LDH) is gaining substantial interest for remediating emerging contaminants, including pharmaceuticals from wastewaters. Findings from a sorbent material performing successfully in lab-based studies using non-environmental (laboratory-sourced) water cannot be assumed to translate to equal performance under environmental downstream applications. However, studies evaluating sorbent material performance for removal of pollutants and understanding material interactions with environmental waters are limited. This study evaluates the removal of the antibiotic amoxicillin (AMX) using a Mg2Al–NO3-LDH sorbent material from laboratory-grade water and wastewater effluent (WWE). AMX is successfully removed (94.53 ± 4.30 % within 24 h) in laboratory-grade water (under batch sorption conditions: 100 μg/L AMX, 0.2 g/L LDH, 20 °C). The comparison of LDH removal performance in laboratory grade and WWE shows a decreased maximum removal of AMX in WWE (13.39 ± 5.53 %). A lower final AMX concentration is observed in the WWE without the presence of LDH, compared to the ‘removal’ experiments in WWE with the presence of LDH, indicating a contribution of non-sorption removal pathways of AMX. This is proposed to be due to the difference in metal concentrations in the WWE with and without LDH present. The presence of LDH is found to decrease concentrations of metal pollutants in WWE, such as Zn concentration decreasing by 85 % over 24 h, changing water characteristics. Overall, this paper reports that an LDH performs differently in laboratory-sourced water and a wastewater effluent. This provides evidence that sorbent material performance needs to be evaluated in complex water matrices to ensure that it is representative of how a sorbent material will perform in an environmental application, which is the end goal of developing such technologies. Finally, good practice recommendations are provided for future lab-scale sorption experiments evaluating the performance of any new sorbent materials for water treatment applications.

An easy, low-cost and efficient method for the extraction of benzoic acid and sorbic acid from orange juice and cola soft drink based on PET plastic stir bar sorptive extraction

In this research, a simple, convenient and low-cost method was used for the simultaneous extraction of benzoic acid (BA) and sorbic acid (SA) with the help of stir bar sorptive extraction (SBSE) method followed by HPLC-UV. Polyethylene terephthalate (PET) was used to cover the stir bar. The source of PET was mineral water plastic bottles, which create a porous polymer coating after dissolving in trifluoroacetic acid (TFA) and mixing with polyvinylpyrrolidone (PVP). The simple strategy of converting waste PET plastic can not only reduce environmental pollution caused by microplastics, but also create an inexpensive and efficient material for coating of stir bar. The obtained polymer was identified by Fourier-transform infrared (FT-IR), field emission-scanning electronic microscope (FE-SEM), X-ray powder diffraction (XRD) and energy dispersion spectroscopy (EDS) techniques. After optimizing the factors affecting the extraction by Box-Behnken design and response surface methodology (RSM), a linear range of 10–7000 μg/L with a coefficient of determination (R2) of more than 0.9984 was obtained for the mentioned compounds. The detection limit for BA and SA was 6 and 5 μg/L, respectively. This method was successfully applied to measure BA and SA in cola soft drink and orange juice samples. The recovery of more than 92.4 % and the error of less than 5.1 % indicate the applicability of this method.

Lithium extraction from geothermal brine using γ-MnO2: A case study for Tuzla geothermal power plant

Geothermal brines contain high concentrations of ions and form a source of various valuable elements. The isolation of the elements from their water systems is a great challenge when the gradual depletion of ores in mining is considered. Attempts have been made for a long time to isolate valuable elements from aqueous mixtures prepared in the laboratory. However, those studies might not reflect the complexity of natural systems and might yield results that deviate significantly from the performance in real field systems. In this study, sorption is used to extract lithium ions from a representative field, Tuzla Geothermal Power Plant (TGPP) Turkey, using a mini-pilot reactor introduced to the reinjection well of the plant. Electrolytic manganese dioxide (γ-MnO2), a relatively inexpensive material widely used as the cathode material in lithium-ion batteries, was employed as a sorbent material for lithium. The sorption/desorption performance of the novel γ-MnO2 was investigated under various conditions. Sorption is performed at 360K and 2 bars. The maximum sorption performance was obtained at 1 h in Tuzla GPP. The desorption experiments were performed in acidic solutions. The concentration of Li+ in the desorption solution was found to be 25 mg/L on average when 10 g of γ-MnO2 was dispersed into 30 mL of the acidic aqueous solution. The first desorption solution was used consecutively for collecting more Li+ ions through the desorption of fresh brine-treated powder samples (cumulative desorption). By repeating this process four times consecutively, 230 mg/L of Li+ was obtained in the desorption solution. Moreover, the reusability of the γ-MnO2 sorbent was examined. The sorbent powder showed almost 40% performance efficiency compared to virgin powder under the conditions employed in this study. The use of electrolytic γ-MnO2 sorbent for lithium adsorption was found to be a promising process for practical use in the separation of lithium from geothermal brines.

Selective separation and recovery of rare-earth elements (REEs) from acidic solutions and coal fly ash leachate by novel TODGA-Impregnated organosilica media

Rare-earth elements (REEs) are essential in a wide range of applications including magnets and satellite technology, with demand driven by geopolitical factors. While multiple techniques exist for REE recovery including solvent extraction and selective precipitation, solid–liquid extraction offers key advantages in selectivity, scalability, and recyclability. N, N, N′, N′-tetraoctyl diglycolamide (TODGA) is a tridentate ligand widely used in solvent extraction, but the incorporation in a solid support to separate individual lanthanides from acid solutions remains largely unexplored. A novel TODGA-organosilica sorbent material was developed and tested to evaluate recovery of 17 elements (REEs and thorium) in terms of selectivity, kinetics, and equilibrium isotherms in 0.01 to 15.9 M nitric acid. Characterization of the new sorbent was performed before and after sorption using FTIR, XPS, and SSA techniques to help elucidate sorption mechanisms and limiting variables. REE adsorption increased from 1.26 mg g−1 to 10 mg g−1 with nitric acid concentrations of 0.01 M and 15.9 M, respectively. TODGA-organosilica exhibits high selectivity towards heavy REEs (Dy to Lu), with minimal sorption of lighter REEs (Ce to Gd). Batch adsorption experiments confirm pseudo-second-order kinetics and a Langmuir adsorption isotherm with TODGA binding to REEs in a 3:1 complex. A packed bed column study confirmed the high selectivity of TODGA-impregnated organosilica towards heavy REEs and a proof-of concept experiment with coal fly ash leachate shows high selectivity for REEs over Al, Fe, and Ca present in several orders of magnitude higher concentrations. Fractionation was observed where loading cycle effluent contained 84 % light REEs while strip cycle effluent contained 80 % heavy REEs. More than 90 % of loaded REEs were successfully stripped with water as the stripping agent.

Magnetically separable sorbent based on activated carbon derived from a new precursor Rhizoclonium hookeri for facile oil spill clean-up

A huge quantity of synthetic toxic materials ends-up in water bodies causing long-lasting environmental and economic impacts due to catastrophic oil spill. Exploring marine algae as sorbent materials for oil spill remediation is a relatively new area and holds great potential. Herein, macroalgae Rhizoclonium hookeri (RH) derived magnetically recoverable RH-activated carbon (RHAC@Fe3O4) composite has been proposed as an innovative and robust strategy for oil spill clean-up. The application of RHAC@Fe3O4 composite was investigated for oil removal by varying time (10–60 min), dosage (0.2–1 g) and temperature (20, 30, 40 °C) to ascertain its optimal performance using both unused and used motor oil. Characterization studies showed that KOH activation resulted in developing pore structure and surface functionalities in the algal biochar. The percentage of oil uptake from simulated oil spill was over 90 % in 30 min at room temperature using 0.8 g composite. Moreover, Fe3O4 loading onto carbon material allowed magnetic separation as a convenient alternative to filtration for the recovery of oil laden composite. Apart from superior oil removal ability, synthesized composite demonstrated robust performance up to four cycles in synthetic sea water matrices. Comparative study revealed better oil sequestration efficiency of RHAC@Fe3O4 (93 %) as compared to its precursors, i.e. algal biochar (71 %) and AC (88 %). Based on these findings, it is advocated that designed RHAC@Fe3O4 composite being eco-friendly, economical and readily recoverable with enhanced oil uptake ability could potentially be an innovative platform for oil spill clean-up applications.

Impact of Protonation Sites on Collision-Induced Dissociation-MS/MS Using CIDMD Quantum Chemistry Modeling.

Protonation is the most frequent adduct found in positive electrospray ionization collision-induced mass spectra (CID-MS/MS). In a parallel report Lee, J. J. Chem. Inf. Model. 2024, 10.1021/acs.jcim.4c00760, we developed a quantum chemistry framework to predict mass spectra by collision-induced dissociation molecular dynamics (CIDMD). As different protonation sites affect fragmentation pathways of a given molecule, the accuracy of predicting tandem mass spectra by CIDMD ultimately depends on the choice of its protomers. To investigate the impact of molecular protonation sites on MS/MS spectra, we compared CIDMD-predicted spectra to all available experimental MS/MS spectra by similarity matching. We probed 10 molecules with a total of 43 protomers, the largest study to date, including organic acids (sorbic acid, citramalic acid, itaconic acid, mesaconic acid, citraconic acid, and taurine) as well as aromatic amines including uracil, aniline, bufotenine, and psilocin. We demonstrated how different protomers can converge different fragmentation pathways to the same fragment ions but also may explain the presence of different fragment ions in experimental MS/MS spectra. For the first time, we used in silico MS/MS predictions to test the impact of solvents on proton affinities, comparing the gas phase and a mixture of acetonitrile/water (1:1). We also extended applications of in silico MS/MS predictions to investigate the impact of protonation sites on the energy barriers of isomerization between protomers via proton transfer. Despite our initial hypothesis that the thermodynamically most stable protomer should give the best match to the experiment, we found only weak inverse relationships between the calculated proton affinities and corresponding entropy similarities of experimental and CIDMD-predicted MS/MS spectra. CIDMD-predicted mechanistic details of fragmentation reaction pathways revealed a clear preference for specific protomer forms for several molecules. Overall, however, proton affinity was not a good predictor corresponding to the predicted CIDMD spectra. For example, for uracil, only one protomer predicted all experimental MS/MS fragment ions, but this protomer had neither the highest proton affinity nor the best MS/MS match score. Instead of proton affinity, the transfer of protons during the electrospray process from the initial protonation site (i.e., mobile proton model) better explains the differences between the thermodynamic rationale and experimental data. Protomers that undergo fragmentation with lower energy barriers have greater contributions to experimental MS/MS spectra than their thermodynamic Boltzmann populations would suggest. Hence, in silico predictions still need to calculate MS/MS spectra for multiple protomers, as the extent of distributions cannot be readily predicted.

Development of Thin Film Microextraction with Natural Deep Eutectic Solvents as 'Eutectosorbents' for Preconcentration of Popular Sweeteners and Preservatives from Functional Beverages and Flavoured Waters.

An eco-friendly method for the determination of sweeteners (aspartame, acesulfame-K) and preservatives (benzoic acid, sorbic acid, methylparaben, ethylparaben) in functional beverages and flavoured waters using thin film microextraction (TFME) and high-performance liquid chromatography with UV detection (HPLC-UV) was proposed. A series of fourteen green and renewable solidified natural deep eutectic solvents (NADESs) were prepared and tested as 'eutectosorbents' in TFME for the first time. In the proposed method, the NADES containing acetylcholine chloride and 1-docosanol at a 1:3 molar ratio was finally chosen to coat a support. Four factors, i.e., the mass of the NADES, pH of the samples, extraction time, and desorption time, were tested in the central composite design to select the optimal TFME conditions. Limits of detection were equal to 0.022 µg mL-1 for aspartame, 0.020 µg mL-1 for acesulfame-K, 0.018 µg mL-1 for benzoic acid, 0.026 µg mL-1 for sorbic acid, 0.013 µg mL-1 for methylparaben, and 0.011 µg mL-1 for ethylparaben. Satisfactory extraction recoveries between 82% and 96% were achieved with RSDs lower than 6.1% (intra-day) and 7.4% (inter-day). The proposed 'eutectosorbent' presented good stability that enabled effective extractions for 16 cycles with recovery of at least 77%. The proposed NADES-TFME/HPLC-UV method is highly sensitive and selective. However, the use of a solid NADES as a sorbent, synthesized without by-products, without the need for purification, and with good stability on a support with the possibility of reusability increases the ecological benefit of this method. The greenness aspect of the method was evaluated using the Complex modified Green Analytical Procedure Index protocol and is equal to 84/100.

Optimized HPLC-UV Methodology for the Simultaneous Quantification of Multiple Preservatives in Jordanian Yogurt Products

A method based on high-performance liquid chromatography with a UV detector (HPLC-UV) was developed for the simultaneous determination of sorbic acid, benzoic acid, and natamycin in yogurt. The method does not require time-consuming, labor-intensive pre-treatment processes or complicated procedures. Using a C18 150 mm × 4.6 mm, 3.0 µm column (Roc) at 25 °C, the target analytes were separated within 5 minutes with high sensitivity and selectivity. The mobile phase consisted of trifluoroacetic acid (0.1%) in water containing 100 mM sodium acetate, trifluoroacetic acid (0.1%) in acetonitrile, and trifluoroacetic acid (0.1%) in tetrahydrofuran, in a ratio of 70:20:10 (v/v). Using this mobile phase as an extraction mixture, recoveries ranged from 83.0% to 110.2% at spike levels between 2.5 µg/kg and 80.0 µg/kg. The relative standard deviations (RSDs) for these recoveries were below 10%. Intra-day precision and inter-day precision varied from 5.3% to 6.7% and 7.6% to 9.2%, respectively. Additionally, the limits of detection (LOD) were between 0.24 and 0.61 mg/L, and the limits of quantification (LOQ) ranged from 0.80 to 2.0 mg/L for sorbic acid, benzoic acid, and natamycin. Principal component analysis revealed that yogurt type had the greatest positive influence on preservative concentration, while the weight or volume of the yogurt package had the greatest negative influence.