Polymeric Sorbent Research Articles

Conductive polymer sorbent for extraction and determination of resveratrol and polydatin in Polygonum cuspidatum root samples.

The quantitative analysis of trace resveratrol and polydatin in plant tissues is suitable for elucidation of the compounds' mechanisms of action. The main objective of this work was to develop a feasible and effective sample pretreatment method to measure the concentrations of resveratrol and polydatin in complex samples. A polymer sorbent, poly(2-mercaptobenzimidazole), was electrochemically prepared and utilized for selective extraction, while resveratrol and polydatin were used as target analytes. The sorbent was characterized by cyclic voltammetry, scanning electron microscopy and Fourier transform infrared spectroscopy. After extraction and elution, the analytes were analyzed by a Thermo U3000 HPLC system. Several affecting parameters, including the volume of elution solution, sample pH value, sample flow rate and sample volume, were evaluated and optimized. The proposed method showed good linearity with low limits of detection (from 0.5 to 0.8ng·mL-1 ) and ideal accuracy with spiked recoveries from 81.30% to 99.16%. A good enrichment factor (more than 200-fold) together with good sensitivity was obtained with this method. Analysis of resveratrol and polydatin in Polygonum cuspidatum samples by this method is efficient. The method developed in this work exhibits several significant merits, including easy operation and high extraction efficiency, indicating that electrochemically prepared polymer sorbent is useful for sample pretreatment and analysis of traditional Chinese medicine samples.

The Effect of the Synthesis Method on Physicochemical Properties of Selective Granular Polymer Sorbents

Investigation of the effect of the polymer synthesis method on physicochemical properties of sorbents is one of the topical problems in the chemistry of macromolecular compounds that has high scientific and practical interest. Determination of the optimal synthesis method will make it possible to create sorbents with physicochemical properties that led to the realization of effective sorption. In this work, we investigated the effect of synthesis methods (Pickering emulsion polymerization and precipitation polymerization in solution) of granular polymers based on 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate on physicochemical and sorption properties. The synthesis by Pickering emulsion polymerization led to improvement of the n-propyl alcohol diffusion into the polymer network and to the formation of more homogeneous and structurally stable polymer networks. Creating selective polymer networks by Pickering emulsion polymerization compared to precipitation polymerization in solution led to an increase in porosity, creation of more segregated surface of granules, improvement of binding sites availability at the temperature of 37 °C, and formation of the homogeneous sorption surface with high affinity to target molecules at 25 °C and 37 °C. Selective polymers synthesized by both polymerization methods had the largest values of available sorption surfaces areas for target molecules at 37 °C.

Revealing the Molecular-Level Interactions between Cationic Fluorinated Polymer Sorbents and the Major PFAS Pollutant PFOA

Revealing the Molecular-Level Interactions between Cationic Fluorinated Polymer Sorbents and the Major PFAS Pollutant PFOA

In English

As opposed to polymer sorbents, inorganic materials are stable against ionizing radiation. This gives a possibility to use them for the removal of radionuclides from water. As a rule, highly selective inorganic sorbents are obtained in a form of finely dispersive powder. This makes it difficult to use them in practice. Here the composites based on hydrated titanium dioxide containing K2Co[Fe(CN)6] have been developed. The modifier was inserted into partially (hydrogel) and fully (xerogel) formed oxide matrices. Modifying of hydrogel followed its transformation to xerogel provides the formation of potassium-cobalt hexacyanoferrate(II) nanoparticles (up to 10 nm), which are not washed out in aqueous media due to encapsulation in hydrated oxide. A number of the methods for sample characterization were used in this work: transmission electronic microscopy for vizualization of embedded nanoparticles, optical microscopy to measure granule size, FT-IR spectroscopy, X-ray fluorescence spectroscopy for chemical analysis of the samples, potentiometric titration to estimate ion exchange properties, and spectrophotometric analysis of the solution to determine U(VI) concentration. The features of U(VI) sorption from nitrate and sulfate solutions are considered: the effect of the sorbent dosage and solution composition was in a focus of attention. The influence of the modifier is the most pronounced at pH ³ 4, when U(VI) is in a form of one-charged cations (UO2OH+): the removal degree of U(VI) is close to 100 %. This positive effect of the selective constituent is expressed in a presence of an excess of NO3–, SO42– and Na+ ions. The model of chemical reaction of pseudo second order has been applied to sorption. Both pristine sorbent and composite are most completely regenerated with a 0.1 M KOH solution - the regeneration degree is 92 and 96 % respectively. In this case, the half-exchange time is minimal and equal to » 23 min (initial hydrated titanium dioxide) and 47 min (composite). Desorption obeys the model of particle diffusion: the diffusion coefficients for ions being exchanged are (1.7–7.6)´10–13 m2s–1.

A new multi-hydroxyl methacrylate based adsorbent for boron removal from aqueous solutions

ABSTRACT A new methacrylate-based multi-hydroxyl functional group carrying polymeric sorbent was prepared starting from spherical beads form crosslinked glycidyl methacrylate-co-ethylene glycol dimethacrylate resin. The beads with epoxy functions can give easily ring opening reaction treatment with excess tris(2-aminoethyl) amine to obtain aminated sorbent. And then, this resin was modified with glycidol to give the corresponding multi-hydroxyl functions. The resulting polymeric sorbent has been shown to be efficient in chelation with boric acid and maximum boron sorption capacity of the resin was found as 4.20 mmol/g resin under non-buffered conditions. According to the boron sorption kinetic results, the resin was shown to be appropriate for removal of boron even at ppm levels. The presence of different ions such as Mg2+, Ca2+, Cl−, SO4 2- have little effect on boron sorption of the resin. After four consecutive adsorption-desorption cycles, the resin gave good performance for re-using.

Separation-preconcentration and ultra trace lead determination in the environmental sample by a combination of ion-imprinted polymer and solidification of floating organic drop microextraction

ABSTRACT The ion-imprinted polymer combined with the solidification of floating organic drop microextraction has been developed as an ultra-pre-concentration technique to determine lead ions in real samples. In ion-imprinted polymer – solidification of floating organic drop microextraction, lead was adsorbed from a large volume of aqueous samples (500 mL) into 100 mg of the ion-imprinted polymer sorbent. After the elution of lead ions from the sorbent by using nitric acid, the solidification of floating organic drop microextraction technique was performed on the obtained solution. Several important extraction parameters, such as weight of ion-imprinted polymer (mg), pH, uptake time (min), desorption time (min), HNO3 desorption volume (mL) aqueous-phase volume (mL), were studied and optimised. The ion–imprinted polymer particles were characterised by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). The new method (SPE–SFODME) provided an ultra-enrichment factor (5000) for lead. The calibration graphs were linear in the range of 5–200 ng L−1. The optimum conditions for the method were as follows: pH of solution, 7.5; weight of ion-imprinted polymer, 100 mg; type and concentration of eluent, HNO3 1 M; volume of eluent, 1 mL; sorption time, 25 min; desorption time, 15 min. Under optimum conditions, the limit of detection (LOD) was 1 ng L−1 for lead and relative standard deviation (RSD %) for five replicate determinations of 10 ng L−1 for lead was 6.5%. The results for the determination of lead ions in reference materials, tap water, ground vegetables, butter and flour wheat demonstrated the accuracy, recovery and applicability of the presented method.

Removal of manganese (II) from aqueous solution by ionic liquid impregnated polymeric sorbent and electrodeionization (EDI) techniques

Manganese is an element that is essential for the proper functioning of humans and animals, as it is needed for the functioning of many cellular enzymes. However, overexposure to this metal can be toxic to many organ systems and at various stages of life. In this work, ionic liquid impregnated polymeric sorbent (ILIS) and electrodeionization (EDI) processes were used to remove manganese (Mn2+) from aqueous solutions. The removal of Mn2+ by ILIS is pH dependent and maximum removal is achieved at pH 9. The sorption of Mn2+ on ILIS reached equilibrium in 20 min. For Mn2+ removal by EDI, the applied potential, feed flow rate and H2SO4 concentration in the electrode compartment were optimized. When the applied potential and feed flow rate were increased, the Mn2+ concentration in the feed solution decreased. Varying the H2SO4 concentration in the electrode compartment did not result in differences in the removal rate. The largest calculated flux for Mn2+ is 6.92 × 10−5 mol/m2s, and the mass transfer coefficient is 8.16 × 10−4 m/s. In the last phase of the experiment, ILIS-EDI hybrid techniques were used for the removal of Mn2+. In this case, more than 99.9% was removed from the solution.

Hypercrosslinked polymer microspheres decorated with anion- and cation-exchange groups for the simultaneous solid-phase extraction of acidic and basic analytes from environmental waters

Mixed-mode ion-exchange sorbents were introduced to improve the selectivity and retention of solid-phase extraction (SPE) sorbents. Mixed-mode ion-exchange sorbents integrate reversed-phase chemistry with ion-exchange groups to promote favourable interactions with ionic species. Nevertheless, a need to extract analytes with acidic and basic properties simultaneously within the same SPE cartridge led to the introduction of novel amphoteric/zwitterionic sorbents, which incorporate cation- and anion-exchange moieties within the same functional group attached to the polymeric network.In the present study, the development, preparation and SPE evaluation of two novel hypercrosslinked zwitterionic polymeric sorbents, functionalised with either strong anion-exchange (SAX) and weak cation-exchange (WCX) or weak anion-exchange (WAX) and strong cation-exchange (SCX) groups (namely HXLPP-SAX/WCX and the HXLPP-WAX/SCX), is presented for the simultaneous retention of acidic and basic compounds. The sorbents were prepared by a precipitation polymerisation route which yielded poly(divinylbenzene-co-vinylbenzylchloride) as a precursor polymer; subsequently, the precursor polymer was hypercrosslinked, to increase the specific surface areas and capacities of the sorbents, and then functionalised to impart the zwitterionic character. The HXLPP-SAX/WCX sorbent was decorated with quaternised sarcosine groups and the HXLPP-WAX/SCX sorbent was decorated with taurine moieties. The SPE parameters were optimised to exploit the ionic interactions between compounds and the functional groups. The optimal conditions involve a washing step to remove the compounds retained by hydrophobic interactions, thus increasing the selectivity. The optimised SPE protocol used the quaternised sarcosine-based sorbent followed by liquid chromatography and tandem mass spectrometry, and was applied to determine compounds with acidic and basic properties from environmental samples, such as river water and effluent wastewater samples, with excellent selectivity and matrix effect values below -30% and apparent recovery results ranging from 52% to 105% for most of the compounds. The analytical method was validated for environmental water samples and used in the analysis of samples in which some of the target compounds were found at ng L−1 concentration levels.

Synthesis, Characterization and Sorption Ability of Epoxy Resin-Based Sorbents with Amine Groups.

Water pollution by toxic substances, such as azo dyes, is a serious environmental problem that needs to be addressed. This study presents the synthesis and characterization of new polymeric sorbents, based on the epoxy resin Epidian® 5 (Ep5), as a potential adsorbent for the removal of the toxic azo dye C.I. Acid Violet 1 (AV1). Triethylenetetramine (TETA) was applied as a cross-linking agent in the amounts of 1 g (6.67 wt %), 1.5 g (10 wt %), and 2 g (13.33 wt %). The use of a compound with amino groups allows for the simultaneous functionalization of the obtained material. The reaction was carried out in an environment of ethylene glycol, with the addition of a porophore solvent (toluene) and bis(2-ethylhexyl)sulfosuccinate sodium salt (S). The attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR) revealed the existence of a strong band in the 828–826 cm−1 range corresponding to the second-order amine group, which indicates their incorporation into the epoxy structure. The glass transition and decomposition temperatures of the resins decreased with the increasing amounts of amine in the material. The thermogravimetry (TGA) analysis demonstrated that all products are thermally stable up to 340 °C. The surface morphology and microstructural properties of the obtained sorbents were determined using scanning electron microscopy (SEM) images and showed an irregular star shape, with dimensions ranging from 400 to 1000 µm. The adsorption capacities of Ep5-TETA1, Ep5-TETA1.5, Ep5-TETA2 and Ep5-TETA1.5 + S for AV1 evaluated during batch experiments were found to be 2.92, 3.76, 7.90 and 3.30 mg/g, respectively.

Experience and lessons learnt in the design, fabrication and deployment of ceramic passive samplers for contaminant monitoring in water

The aim of this study is to describe the steps and complications encountered in the design, fabrication and calibration of ceramic passive samplers for the analysis of water contaminants. A ceramic passive samplers consists in a porous ceramic tube where a polymeric sorbent is placed in the inner side to preconcentrate the analytes from water with high enrichment factors. The diffusivity and uptake of contaminants depend on the ceramic porous structure that influences the sampling rate. Although the concept stands up for its simplicity, in real life passive samplers face several problems: fouling, clogging and saturation and then the uptake of contaminants may not be linear during the deployment period. With ceramic passive samplers these problems can be solved by optimizing the ceramic structure and porosity. Over eight year period, we have had a fruitful collaboration with Prof. Victor Orera, aimed to develop customized ceramic membranes to unselectively accumulate the contaminants present in different types of water with the overarching objective to monitor chemical pollution present in the environment. The use of customized ceramic passive samplers (CPS) will permit to identify main compounds in water, their evolution in time, identify the sources of pollution and finally gather enough knowledge and data to effectively propose control and remediation actions. In this study, we describe the steps undertaken in the development of ceramic samplers, their characteristics, the calibration procedure used, their performance and applicability. The work herein presented has been possible due to the brilliant ideas, enthusiasm, perseverance and motivation of Prof. Orera, but also because his joyful and cheerful character made this collaboration really pleasant and valuable.

Disinfection Byproduct Recovery during Extraction and Concentration in Preparation for Chemical Analyses or Toxicity Assays.

Over 700 disinfection byproducts (DBPs) have been identified, but they account for only ∼30% of total organic halogen (TOX). Extracting disinfected water is necessary to assess the overall toxicity of both known and unknown DBPs. Commonly used DBP extraction methods include liquid-liquid extraction (LLE) and solid-phase extraction (SPE), which may use either XAD resins or other polymeric sorbents. With few exceptions, DBP recoveries have not been quantified. We compared recoveries by LLE, XAD resins, and a mixture of Phenomenex Sepra SPE sorbents (hereafter SPE) for (semi-)volatile DBPs and nonvolatile model compounds at the 1-L scale. We scaled up the three methods to extract DBPs in 10 L of chlorinated creek waters. For (semi-)volatile DBPs, XAD resulted in lower recoveries than LLE and SPE at both 1- and 10-L scales. At the 10-L scale, recovery of certain trihalomethanes and trihalogenated haloacetic acids by XAD was negligible, while recovery of other (semi-)volatile DBPs extracted by XAD (<30%) was lower than by SPE or LLE (30-60%). TOX recovery at the 10-L scale was generally similar by the three extraction methods. The low TOX recovery (<30%) indicates that the toxicity assessed by bioassays predominantly reflects the contribution of the nonvolatile, hydrophobic fraction of DBPs.

A Database of Experimentally Derived and Estimated Octanol–Air Partition Ratios (KOA)

Equilibrium partition coefficients or partition ratios are a fundamental concept in physical chemistry, with wide applications in environmental chemistry. While comprehensive data compilations for the octanol–water partition ratio and the Henry’s law constant have existed for many years, no comparable effort for the octanol–air partition ratio (KOA) exists. Considering the increasing use of KOA in understanding a chemical’s partitioning between a wide variety of organic phases (organic phases in atmospheric particles, plant foliage, polymeric sorbents, soil organic matter, animal tissues, etc.) and the gas phase, we have compiled all KOA values reported in the published literature. The dataset includes more than 2500 experimentally derived values and more than 10 000 estimated values for KOA, in total covering over 1500 distinct molecules. The range of measured log10 KOA values extends from −2 to 13. Many more measured values have been reported in the log10 KOA range from 2 to 5 and from 6 to 11 compared to the range from 5 to 6, which is due to the complementary applicability range of static and dynamic measurement techniques. The compilation also identifies measured data that are judged not reliable. KOA values for substances capable of undergoing strong hydrogen bonding derived from regressions with retention times on nonpolar gas chromatographic columns deviate strongly from values estimated by prediction techniques that account for such intermolecular interactions and should be considered suspect. It is hoped that the database will serve as a source for locating existing KOA data and for the calibration and evaluation of new KOA prediction techniques.

Development of a novel, through-flow microwave-based regenerator for sorbent-based direct air capture

In this work an all-electric regenerator is developed for the desorption of CO2 from air-capture sorbents using microwaves. An electromagnetic model was made for a continuous flow radial desorber and its dimensions were optimised for maximal microwave utilisation. Based on the optimal dimensions an actual prototype, capable of desorbing CO2 from a commercial supported amine sorbent in fixed- or moving-bed configuration was built to demonstrate the concept and to study performance characteristics. TSA experiments using nitrogen as purge gas to produce enriched air (1 to 2 vol.% CO2) were done. Productivities of up to 1.5 kgCO2/kgsorb./d were demonstrated, with a total energy duty of 25 MJ/kgCO2. Compared to traditional TVSA desorption, the energy duty is similar while the productivity is significantly higher. The process can be further improved by creating an even more homogeneous electric field (preventing hot spots in the regenerator) and by enabling desorption under vacuum conditions to produce pure CO2. Overall, microwave desorption is demonstrated as an effective way to circumvent heat transfer limitations present during more traditional thermal desorption processes using polymeric sorbents.

Reliable Prediction of the Octanol-Air Partition Ratio.

The octanol–air equilibrium partition ratio (K OA) is frequently used to describe the volatility of organic chemicals, whereby n‐octanol serves as a substitute for a variety of organic phases ranging from organic matter in atmospheric particles and soils, to biological tissues such as plant foliage, fat, blood, and milk, and to polymeric sorbents. Because measured K OA values exist for just over 500 compounds, most of which are nonpolar halogenated aromatics, there is a need for tools that can reliably predict this parameter for a wide range of organic molecules, ideally at different temperatures. The ability of five techniques, specifically polyparameter linear free energy relationships (ppLFERs) with either experimental or predicted solute descriptors, EPISuite's KOAWIN, COSMOtherm, and OPERA, to predict the K OA of organic substances, either at 25 °C or at any temperature, was assessed by comparison with all K OA values measured to date. In addition, three different ppLFER equations for K OA were evaluated, and a new modified equation is proposed. A technique's performance was quantified with the mean absolute error (MAE), the root mean square error (RMSE), and the estimated uncertainty of future predicted values, that is, the prediction interval. We also considered each model's applicability domain and accessibility. With an RMSE of 0.37 and a MAE of 0.23 for predictions of log K OA at 25 °C and RMSE of 0.32 and MAE of 0.21 for predictions made at any temperature, the ppLFER equation using experimental solute descriptors predicted the K OA the best. Even if solute descriptors must be predicted in the absence of experimental values, ppLFERs are the preferred method, also because they are easy to use and freely available. Environ Toxicol Chem 2021;40:3166–3180. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

β-Cyclodextrin Derivative Grafted on Silica Gel Represents a New Polymeric Sorbent for Extracting Nitisinone from Model Physiological Fluids.

Nitisinone (NTBC) is used in the treatment of disorders affecting the tyrosine pathway, including hereditary tyrosinemia type I, alkaptonuria, and neuroblastoma. An inappropriate dosage of this therapeutic drug causes side effects; therefore, it is necessary to develop a rapid and sensitive method to monitor the content of NTBC in patients’ blood. This study aimed to develop anew polymeric sorbent containing β-cyclodextrin (β-CD) derivatives grafted on silica gel to effectively extract NTBC from model physiological fluids. The inclusion complex formed between β-CD and NTBC was examined by proton nuclear magnetic resonance spectroscopy. The novel sorbents with derivatives of β-CD were prepared on modified silica gel using styrene as a comonomer, ethylene glycol dimethacrylate as a crosslinking agent, and 2,2′-azo-bis-isobutyronitrile as a polymerization initiator. The obtained products were characterized via Fourier transform infrared spectroscopy and then used as sorbents as part of a solid phase extraction technique. High NTBC recovery (70%indicated that the developed polymeric sorbent may be suitable for extracting this compound from patients’ blood samples.

Polymeric Fiber Sorbents Embedded with Porous Organic Cages.

The synthesis and functionalization of porous organic cages (POCs) for separation have attracted growing interest over the past decade. However, the potential of solid-phase POCs for practical, large-scale separations will require incorporation into appropriate gas-solid or liquid-solid contactors. Contactors with more effective mass transfer properties and lower pressure drops than pelletized systems are preferred. Here, we prepared and characterized fiber sorbents with POCs throughout a cellulose acetate (CA) polymer matrix, which were then deployed in model separations. The POC CC3 was shown to be stable after exposure to spinning solvents, as confirmed by NMR, powder X-ray diffraction, and gas sorption experiments. CC3-CA fibers were spun using the dry-jet wet-quench spinning method. Spun fibers retained the adsorptive properties of CC3 powders, as confirmed by CO2 and N2 physisorption and TGA, reaching upward of 60 wt % adsorbent loading, whereas the pelletized CC3 counterparts suffered significant losses in textural properties. The separation capabilities of the CC3-CA fibers are tested with both simulated postcombustion flue gas and with Xe/Kr mixtures. Fixed bed breakthrough experiments performed on fibers samples show that CC3 embedded in polymeric fibers can effectively perform these proof-of-concept gas separations. The development of fiber sorbents embedded with POCs provides an alternative to traditional pelletization for the incorporation of these materials into adsorptive separation systems.

Mercury emission profile for the torrefaction of sewage sludge at a full-scale plant and application of polymer sorbent

We evaluated mercury (Hg) behavior in a full-scale sewage sludge torrefaction plant with a capacity of 150 wet tons/day, which operates under a nitrogen atmosphere at a temperature range of 250–350 °C. Thermodynamic calculations and monitoring results show that elemental Hg (Hg0) was the dominant species in both the pyrolysis gas during the torrefaction stage and in the flue gas from downstream air pollution control devices. A wet scrubber (WS) effectively removed oxidized Hg from the flue gas and moved Hg to wastewater, and an electrostatic precipitator (ESP) removed significant particulate-bound Hg but showed a limited capacity for overall Hg removal. Hg bound to total suspended solids had a much higher concentration than that of dissolved Hg in wastewater. Total suspended solid removal from wastewater is therefore recommended to reduce Hg discharge. Existing air pollution control devices, which consist of a cyclone, WS, and ESP, are not sufficient for Hg removal due to the poor Hg0 removal performance of the WS and ESP; a further Hg0 removal unit is necessary. A commercial packed tower with sorbent polymer catalyst composite material was effective in removing Hg (83.3%) during sludge torrefaction.

Novel Polymer Sorbents with Imprinted Task-Specific Ionic Liquids for Metal Removal.

In this paper, the potential of novel polymer sorbents with the imprinted IL-functional group for the removal of Cu(II), Cd(II), and Zn(II) from aqueous solutions was investigated by batch mode. The sorbents were fabricated by direct reaction of the prepared polymer matrix (poly(vinylbenzyl chloride-divinylbenzene), VBC, and poly(vinylbenzyl bromide-divinylbenzene), VBBr) with 1-(3- or 4-pyridyl)undecan-1-one and oxime of 1-(3- or 4-pyridyl)undecan-1-one. The Fourier Transform Infrared Spectroscopy (FT-IR), Raman Spectroscopy (Raman), Thermogravimetric Analysis (TG), Differential Scanning Calorimetry (DSC), and Scanning Electron Microscopy (SEM) techniques were used to show functionality and stability of the sorbents. The materials were also characterized by contact-angle goniometry, X-rayphotoelectron spectroscopy (XPS), and Zeta potential analysis. The removal of Cd(II), Cu(II), and Zn(II) was monitored and optimized under the influence of several operational controlling conditions and factors such as pH, shaking time, temperature, initial metal ions concentration, and counter-ions at the functional group. The results obtained confirmed the very high potential of the sorbents; however, the properties depend on the structure of the functional group. The tested sorbents showed fast kinetics, significant capacity at 25 °C (84 mg/g for the Zn(II) sorption with VBC-Ox4.10, 63 mg/g for the Cd(II) sorption with VBBr-Ox3.10, and 69 mg/g for the Cu(II) sorption with VBC-K3.10), and temperature dependence (even 100% increase in capacity values at 45 °C). The selected sorbent can be regenerated without a significant decrease in the metal removal efficiency.

Bile salts adsorption on dextran-based hydrogels

Dextran-based gels bearing two types of pendant N, N-dimethyl-N-alkyl-N-(2-hydroxypropyl) ammonium chloride groups with different alkyl chain length substituents (C2 and C12/C16, respectively) at the quaternary nitrogen were synthesized and structural characteristics of the compounds were studied by elemental analysis, potentiometric titration, FTIR and NMR spectroscopy. The morphology and size of polymeric microspheres were examined by SEM and their swelling behavior in water was also investigated. The hydrogels were evaluated as sorbents for sodium cholate (NaCA) and sodium deoxycholate (NaDCA) in water and 10 mM NaCl solutions. Different isotherm models (nearest-neighbor-interaction, Langmuir, Freundlich, Dubinin-Raduskevich, Sips and Hill) were used to elucidate the adsorption mechanism and established the characteristics of the most efficient polymeric sorbent. The maximum adsorption capacity of the gels was highly controlled by gel hydrophobicity which enhanced gel-bile salt affinity but decreased binding cooperativity. Swelling porosity, ionic strength and ligand lipophilicity were other factors that also affected the adsorption process. The hydrogel having 25 mol% pendant dodecyl groups retained the maximum amount of bile salts (1051 mg NaCA/g and 1138 mg NaDCA/g). All hydrophobically modified hydrogels revealed a better affinity and strength of binding compared to commercial Cholestyramine®.

On the issue of analytical control of quinone derivatives in habitats

Introduction. In the direction of normative and methodological assurance of the safety of environmental objects and imported food products, analytical approaches to the determination of a fungicide of the quinone class - dithianone in the air and citrus fruits were optimized. Materials and methods. Measurements were performed by tandem liquid mass spectrometry with a triple quadrupole mass detector (HPLC-MS/MS) in multiple reaction monitoring (MRM) mode using electrostatic spray as the ionization source. The substance from the air was concentrated on Tenax TA sorption tubes based on a porous polymer sorbent, followed by extraction of dithianone from the tubes with acetone. The preparation of samples of citrus fruits was carried out by extraction of acidified acetonitrile (selected optimal pH 2) in the presence of salts of magnesium sulfate, sodium chloride and sodium citrate two- and three-substituted, followed by centrifugation and filtration of the extract through disposable syringe membrane filters (QuEChERS technology). Results. The developed techniques were tested on real samples using the pesticide in agricultural practice. The revealed levels of dithianon do not exceed the lower limit of quantitative determination: 0.000071 mg/m3 in ambient air (with an RISL value of 0.0001 mg/m3) and 0.01 mg/kg in citrus fruits (with an established MRL value of 3 mg/kg). Conclusion. The developed methods are approved as official documents and supplement the base of analytical methods in terms of control of atmospheric air and imported food products.