Solid phase extraction of lactic acid from fermentation broth by anion-exchangeable silica confined ionic liquids

Earthworms' Degradable Bioplastic Diet of Polylactic Acid: Easy to Break Down and Slow to Excrete

Microplastics (MPs) in soils may be ingested by terrestrial animals. While the application of bioplastics is increasing, the ingestion and excretion characteristics of bio-MPs by terrestrial animals are poorly understood as compared to fossil-MPs. Here, the approach-avoidance behavior of adult earthworms Eisenia fetida to MP-contaminated soil was assessed. Fossil-based poly(ethylene terephthalate) (PET) and bio-based poly(lactic acid) (PLA) MPs were found to be preferred by the earthworms, which might be due to the odor of polymer monomers. MPs in earthworm casts were analyzed by microscopy counting and liquid chromatography-tandem mass spectrometry. The amount of microscopically recognizable excreted PET and PLA was 553 and 261 items/g, respectively, while a higher proportion of smaller PLA particles also presented. Bio-based PLA is much easy to break down by earthworms than fossil-based PET. Submicron and nanocron PLA accounted for 57 and 13% of the excreted PLA on the 10th day of excretion. MP excretion was well described with the first-order kinetic model, and the elimination half-life was 9.3 (for PET) and 45 h (for PLA). A longer excretion period of PLA may be related to its potential to break down in the earthworms' digestive tract. This not only promotes the environmental degradation of PLA but also suggests the ecological risk caused by nanoparticles.

Silica gel impregnated with deep eutectic solvent-based matrix solid-phase dispersion followed by high-performance liquid chromatography for extraction and detection of triazine herbicides in brown sugar

A novel method was developed to determine six triazine herbicides from brown sugar samples using matrix solid-phase dispersion (MSPD) based on silica gel impregnated with deep eutectic solvent (DES) followed by high-performance liquid chromatography with photodiode array detector (HPLC/PDA). Several factors involved in the MSPD procedure such as DES type, DES content in impregnated silica gel, adsorbent-to-sample mass ratio, type and volume of washing solvent, type and volume of eluent, and grinding time were screened using single-factor experiments and then optimized using Box-Behnken design to accomplish the highest recoveries. The above method demonstrated a good linear range (20-1000 μg kg^-1) with a determination coefficient exceeding 0.9962, low limits of determination (1.59-3.77 μg kg^-1), acceptable limits of quantifications, and acceptable spiking recoveries (95.0-101.7%) for six triazines under optimized conditions. The proposed MSPD-HPLC/PDA method is a convenient, effective, and sensitive method for rapidly isolating and quantifying six triazines from brown sugar.

A Wake-Up Call for the Efficient Use of the Bacterial Resting Cell Process, with Focus on Low Solubility Products

Micro-organisms are often subjected to stressful conditions. Owing to their capacity to adapt, they try to rapidly cope with the unfavorable conditions by lowering their growth rate, changing their morphology, and developing altered metabolite production and other stress-related metabolism. The stress-related metabolism of the cells which interrupted their growth is often referred to as resting metabolism and can be exploit for specific and high rate production of secondary metabolites. Although the bacterial resting cell process has been described decades ago, we find it worthwhile to bring the process under renewed attention and refer to this type of processes as non-growing metabolically active (NGMA) cell processes. Despite their use may sound counterproductive, NGMA cells can be of interest to increase substrate conversion rates or enable conversion of certain substrates, not accessible to growing cells due to their bacteriostatic nature or requirement of resistance to a multitude of different stress mechanisms. Biomass reuse is an interesting feature to improve the economics of NGMA cell processes. Yet, for lipophilic compounds or compounds with low solubility, biomass separation can be delicate. This review draws the attention on existing examples of NGMA cell processes, summarizing some developmental tools and highlighting drawbacks and opportunities, to answer the research question if NGMA cells can have a distinct added value in industry. Particular elaboration is made on a novel and more broadly applicable strategy to enable biomass reuse for conversions of compounds with low solubility.

Magnetically stabilized bed packed with synthesized magnetic silicone loaded with ionic liquid particles for efficient enrichment of flavonoids from tree peony petals

In this work, synthesized magnetic silicone loaded with ionic liquid (Fe₃O₄@SiO₂@IL) particles combined with gas-liquid-solid magnetically stabilized bed (GLS-MSB) were applied to enrich flavonoids from tree peony petal extraction solution. The magnetic core (Fe₃O₄) encased in silica was conducive to its rapid and efficient separation, and the modification of silica with ionic liquids (ILs) could provide the functional groups for selective adsorption of flavonoids. Furthermore, the magnetic materials were evenly dispersed in the GLS-MSB system, realizing the adequate contact and causing the positive influence on the result. After physicochemical characterization, the prepared Fe₃O₄@SiO₂@IL (IL=VBimBr) particles were validated in the enrichment performance of flavonoids, including the type of ionic liquid loaded, desorption solution, adsorption and desorption kinetics. The adsorption kinetics obeyed the pseudo-second-order model, the adsorption isotherms were consistent with the Langmuir equation, and the adsorption process was spontaneous and exothermic. Additionally, the dynamic processes using GLS-MSB packed with Fe₃O₄@SiO₂@IL particles were evaluated systematically, deriving the optimum conditions (5 mL/min liquid flow rate, 130 mL Loading amount and 42.55 Oe magnetic field intensity) and improving the purity of flavonoids. After enrichment, the Fe₃O₄@SiO₂@IL particles were successfully recycled and reused. Overall, the developed method offers a great potential for the enrichment of flavonoids from natural materials.

Homogenous formation and quaternization of urea-functionalized imidazolyl silane and its immobilization on silica for surface-confined ionic liquid stationary phases

New strategy for surface modification of silica sphere was proposed on the basis of one-pot urea formation and quaternization of imidazole, resulting in sorbents of high tunability and controllable hydrophobicity.

Polyhydroxy glucose functionalized silica for the dehydration of bio-ethanol distillate

Although most of the water in a bio-ethanol fermentation broth can be removed by distillation, a small amount of water remains in the bio-ethanol distillate as the water-ethanol azeotrope. To improve the use of ethanol as a fuel, glucose-modified silica, as an adsorbent, was prepared using a facile method and applied to the dehydration of bio-ethanol distillate. The factors affecting the adsorption capacity of the adsorbent, such as the particle size, initial concentration of water in the samples, adsorption temperature and adsorbent dose, were examined by measuring the adsorption kinetics and equilibrium. The Langmuir, Freundlich and Temkin isotherms were used to evaluate the adsorption efficiency. Of these, the Freundlich and Temkin isotherms showed a good correlation with the experimental data. The Langmuir isotherm showed some deviation from the experimental results, and indicated that adsorption in this case was not a simple monolayer adsorption. The property of the adsorbent was attributed to functionalized silica with many hydroxyl groups on its surface. An examination of the separation factors of water/ethanol revealed the modified silica to have preferential selectivity for water. Compared to activated carbon and silica, glucose-modified silica exhibited higher adsorption capacity for water under the same adsorption conditions. In addition, the glucose-modified silica adsorbent exhibited a relatively constant adsorption capacity for five adsorption/desorption cycles.

Determination of polar aromatic amines using newly synthesized sol-gel titanium (IV) butoxide cyanopropyltriethoxysilane as solid phase extraction sorbent

A solid phase extraction (SPE) method has been developed using a newly synthesized titanium (IV) butoxide-cyanopropyltriethoxysilane (Ti-CNPrTEOS) sorbent for polar selective extraction of aromatic amines in river water sample. The effect of different parameters on the extraction recovery was studied using the SPE method. The applicability of the sorbents for the extraction of polar aromatic amines by the SPE was extensively studied and evaluated as a function of pH, conditioning solvent, sample loading volume, elution solvent and elution solvent volume. The optimum experimental conditions were sample at pH 7, dichloromethane as conditioning solvent, 10 mL sample loading volume and 5 mL of acetonitrile as the eluting solvent. Under the optimum conditions, the limit of detection (LOD) and limit of quantification (LOQ) for solid phase extraction using Ti-CNPrTEOS SPE sorbent (0.01-0.2; 0.03-0.61 µg L(-1)) were lower compared with those achieved using Si-CN SPE sorbent (0.25-1.50; 1.96-3.59 µg L(-1)) and C18 SPE sorbent (0.37-0.98; 1.87-2.87 µg L(-1)) with higher selectivity towards the extraction of polar aromatic amines. The optimized procedure was successfully applied for the solid phase extraction method of selected aromatic amines in river water, waste water and tap water samples prior to the gas chromatography-flame ionization detector separation.

Comparison and evaluation of five types of imidazole-modified silica adsorbents for the removal of 2,4-dinitrophenol from water samples with the methyl group at different positions of imidazolium ring

The objective of this work was to improve the understanding the influence of the methyl group at different positions of imidazolium ring on the adsorption behaviors of imidazole-modified silica adsorbents. Five adsorbents named as SilprImCl, SilprM₁ImCl, SilprM₂ImCl, SilprM₄ImCl and SilprM₁M₂ImCl were synthesized using imidazole, 1-methylimidazole, 2-methylimidazole, 4-methylimidazole and 1,2-dimethylimidazole, respectively. These adsorbents were characterized by scanning electron microscope, infrared spectra, thermogravimetric analysis, elemental analysis and BET analysis. Firstly, phenol, 2-nitrophenol (2-NP), 3-nitrophenol (3-NP), 4-nitrophenol (4-NP) and 2,4-dinitrophenol (2,4-DNP) were used as adsorbates to investigate the selectivity of SilprImCl and its adsorption capacities followed the order of 2,4-DNP≫4-NP>2-NP≫3-NP>phenol. Therefore, 2,4-DNP was used to investigate the adsorption behaviors of the five adsorbents. It was inferred that the adsorbents are of primary anion-exchange and electrostatic nature. The electrostatic nature was affected significantly by the methyl group at different positions of imidazolium ring. The adsorbed amounts of 2,4-DNP decreased in the order of: SilprM₁M₂ImCl≈SilprM₁ImCl>SilprM4ImCl>SilprM₂ImCl>SilprImCl. The adsorption-elution experiments indicated that 2,4-DNP can be removed from aqueous solutions by a SilprM₄ImCl packed column and the recovery of 91.6% was obtained. The adsorbent could be regenerated and reused ten times at least by simple washings with HCl and water in turn.

Selective isolation of hemoglobin by use of imidazolium-modified polystyrene as extractant

Ionic liquids have attracted much attention in the analysis of a variety of species. The functional groups in ionic liquids can result in highly efficient separation and enrichment and, because of their typical lack of volatility, they are environmentally benign. We grafted imidazole cations onto the surface of chloromethyl polystyrene, denoted PS-CH2-[MIM](+)Cl(-), and this modified polymer was used to selectively extract the protein hemoglobin (Hb). The prepared extractant PS-CH2-[MIM](+)Cl(-), containing 2 mmol immobilized imidazole groups per gram polymer, was characterized by FT-IR, surface charge analysis, and elemental analysis. The adsorption efficiency was 91%. The adsorption capacity of the PS-CH2-[MIM](+)Cl(-) for Hb was 23.6 μg mg(-1), and 80% of the retained Hb could be readily recovered by use of 0.5% (m/v) aqueous sodium dodecyl sulfate (SDS) solution as eluate. The activity of the eluted Hb was approximately 90%. The prepared imidazole-containing solid phase polymer was used for direct adsorption of Hb without use of any other solid matrix as support of the ionic liquid. The material was used in practice to isolate Hb from human whole blood.

Multi-phase extraction of glycoraphanin from broccoli using aminium ionic liquid-based silica

INTRODUCTION

Glucosinolates, a class of phytochemicals found in broccoli, have attracted recent interest due to the potential health benefits associated with their dietary intake. Glucoraphanin, the most common glucosinolate in broccoli can be converted to a known cancer chemopreventive agent. Multi-phase extraction in solid-phase extraction cartridges was developed to simultaneously extract and separate this compound.

OBJECTIVE

Multi-phase extraction with functionalised ionic liquid-based silica as a sorbent was used to simultaneously extract and separate glucoraphanin from broccoli.

METHODOLOGY

The sorbent and broccoli sample were packed into a single cartridge, and a fixed volume of water was then used to extract and remove the target compound from the sample to the sorbent over 15 repetitions. The sorbent was then washed with n-hexane to remove any interference and the target compound was eluted with water-1% acetic acid (vol.).

RESULTS

Under the optimised condition, 0.038 mg/g of glucoraphanin was obtained by multi-phase extraction with 0.2 g of sorbent.

CONCLUSION

The adsorption isotherm allowed investigation of the interactions between the sorbent and target compound and provided evidence for the accuracy of this method. The low deviation error, small amount of solvents required, highly selective separation and stability of the method justify further research.

Ionic liquid-modified materials for solid-phase extraction and separation: a review

In recent years, materials science has propelled to the research forefront. Ionic liquids with unique and fascinating properties have also left their footprints to the developments of materials science during the last years. In this review we highlight some of their recent advances and provide an overview at the current status of ionic liquid-modified materials applied in solid-phase extraction, liquid and gas chromatography and capillary electrochromatography with reference to recent applications. In addition, the potential of ionic liquids in the modification of capillary inner wall in capillary electrophoresis is demonstrated. The main target material modified with ionic liquids is silica, but polymers and monoliths have recently joined the studies. Although imidazolium is still clearly the most commonly used ionic liquid for the covalently modification of materials, the exploitation of pyridinium and phosphonium will most probably increase in the future.