Sorption preconcentration in combined methods for the determination of noble metals

Combined methods for the determination of noble metals with the use of sorption preconcentration with complexing, anion-exchange, and other sorbents are reviewed. Characteristics of sorbents, techniques of sorption preconcentration, and techniques for the preparation of a concentrate for determination are considered. Features of instrumental methods for the determination of noble metals in the analysis of different materials are discussed. Examples of the use of sorption preconcentration in combined methods for the determination of noble metals are given from publications between 1996–2005.     

Technology for Joint Production of Bromine and Lithium Bromide from Brines from Siberian Platform

Two methods for obtaining bromine and lithium bromide from highly mineralized brines enriched with lithium- and bromine-containing compounds, with Li : Br atomic ratio of 0.4-0.8, were studied. These methods are based on a combination of the technique for production of bromine and sorption recovery of lithium from brines to give eluates, LiCl solutions.     

Complexation with Metal Chelates at the Phase Interface in Gas Chromatography

A review of studies on the use of the chelate complexes as adsorbents and stationary liquid phases in gas chromatography is made. Data on the processes of complex formation at the phase interface and on the target production of the chelate-containing sorbents with preset properties are generalized. Practical application of the chelate-containing chromatographic packings for analytical separation and sorption concentration of organic substances is considered.     

A New Sorption Method for the Production of <Emphasis Type="Italic">Bacillus subtilis</Emphasis> α-Amylase with the Use of FAF Microfine Anion Exchanger

A new sorption method for the production of highly purified hydrolytic enzyme α-amylase from Bacillus subtilis with the use of FAF microfine anion exchanger was developed. The α-amylase enzyme obtained is suitable for the preparation of enzymatic drugs.     

载铁复合环境材料的制备及对水体中砷的深度净化

铁及水合氧化铁可通过配位作用实现对砷的高效吸附分离,但因其颗粒板细,难以直接应用于水体砷污染控制中.将铁及水合氧化铁负载于多孔材料内表面制备载铁复合环境材料是解决这一问题的有效途径.目前国内外在载铁复合环境材料的制备与表征、吸附及再生性能、除砷机理、材料稳定性等方面进行了广泛的研究,部分材料已实现工业化生产与应用.本文简要综述了国内外常见载铁复合环境材料的制备方法及其除砷性能.     

Assessment of the sorption capacity and regeneration of carbon dioxide sorbents using thermogravimetric methods

Adsorption methods using solid sorbents are an alternative to the absorption technology in the processes of purification gases from carbon dioxide. There is a need to rapidly assess the suitability of sorbents for use it in PSA, TSA, or VPSA installations. Important parameters which determine the quality of the sorbent are the sorption capacity of sorbent, selectivity to CO₂ and the possibility of regeneration. This paper presents the results of sorption/desorption of CO₂ study on the impregnated porous materials using thermogravimetric methods. Thermogravimetry allows for rapid assessment of sorption capacity and regeneration of the sorbents. Specially selected temperature program allowed to determine the sorption capacity of sorbents depending on the concentration of CO₂ in the gas mixture and temperature. Degree of sorbent purification was determined in desorption process.     

Cellulose nanocrystal surface functionalization for the controlled sorption of water and organic vapours

The surface grafting of cellulose nanocrystals (CNC) is a valuable tool to increase opportunities for their application. This work had several goals designed to improve CNC: reduction of hornification, increased re-dispersibility after CNC drying, and tuning of the surface graft to enhance the adsorption of particular molecules. To achieve this, the CNC surfaces were modified chemically with aromatic surface grafts using widely employed methods: the creation of urethane linkages, silylation and esterification. Even a low degree of grafting sufficed to increase water contact angles to as much as 96°. The analysis of water sorption isotherms showed that at high water activities, capillary condensation could be suppressed and hysteresis was decreased. This indicates that hornification was significantly suppressed. However, although the contact angles increased, the water sorption isotherms were changed only slightly because of reduced hysteresis. The grafts were not able to shield the surface from water vapour sorption. A comparison of the sorption isotherms of anisole and cyclohexane, sorbates with a similar surface area, showed that the sorption of anisole was three times higher than that of cyclohexane. The specific sorption of aromatic molecules was achieved and the most efficient methodology was the esterification of CNC with carboxylic acids containing a flexible linker between the aromatic moiety and ester bond.     

Metal Sorption by Materials with a Mobile Phase of Extractants

Data on sorption of rare, noble, radioactive, and nonferrous metals from aqueous solutions by impregnates and TVEXs were analyzed. These are materials combining the properties of sorbents and extractants and differing in the production method. Their distinctive feature is that the extractant is not chemically bonded to the solid support, which is responsible for high kinetic characteristics of sorption processes involving these materials, favorably comparing with conventional sorbents. As a mobile phase to be deposited on the carrier (mainly polymeric) in the case of impregnates or to be introduced during synthesis of TVEXs served organophosphorus extractants, amines, quaternary ammonium bases, etc. Information regarding the effect of various parameters (solution acidity, metal concentration, phase ratio, temperature, and concentration of impurity elements) on separating capability and metal sorption capacity and kinetics was provided for this type of materials. Methods used for stabilizing the properties of impregnates with the view to minimize the extractant loss during application were considered.

     

Supramolecular Solvent-Based Microextraction of Selected Anticonvulsant and Nonsteroidal Anti-Inflammatory Drugs from Sediment Samples

The increase in the production and consumption of pharmaceuticals increases their presence in the global environment, which may result in direct threats to living organisms. For this reason, there is a need for new methods to analyze drugs in environmental samples. Here, a new procedure for separating and determining selected drugs (diclofenac, ibuprofen, and carbamazepine) from bottom sediment and water samples was developed. Drugs were determined by ultra-high performance liquid chromatography coupled with an ultraviolet detector (UHPLC-UV). In this work, a universal and single-step sample treatment, based on supramolecular solvents (SUPRAS), was proposed to isolate selected anticonvulsants and nonsteroidal anti-inflammatory drugs (NSAIDs) from sediment samples. The following parameters were experimentally selected: composition of the supramolecular solvent (composition THF:H₂O (v/v), amount of decanoic acid), volume of extractant, sample mass, extraction time, centrifugation time, and centrifugation speed. Finally, the developed procedure was validated. A Speedisk procedure was also developed to extract selected drugs from water samples. The recovery of analytes using the SUPRAS procedure was in the range of 88.8–115%, while the recoveries of the Speedisk solid-phase extraction procedure ranged from 81.0–106%. The effectiveness of the sorption of the tested drugs by sediment was also examined.     

Application of polyurethane foam as a sorbent for trace metal pre-concentration — A review

The first publication on the use of polyurethane foam (PUF) for sorption processes dates back to 1970, and soon after the material was applied for separation processes. The application of PUF as a sorbent for solid phase extraction of inorganic analytes for separation and pre-concentration purposes is reviewed. The physical and chemical characteristics of PUF (polyether and polyester type) are discussed and an introduction to the characterization of these sorption processes using different types of isotherms is given. Separation and pre-concentration methods using unloaded and loaded PUF in batch and on-line procedures with continuous flow and flow injection systems are presented. Methods for the direct solid sampling analysis of the PUF after pre-concentration are discussed as well as approaches for speciation analysis. Thermodynamic proprieties of some extraction processes are evaluated and the interpretation of determined parameters, such as enthalpy, entropy and Gibbs free energy in light of the physico-chemical processes is explained.     

Behavior of a Chitosan–Drug System during Diffusion Processes

The process of water vapor sorption by medical chitosan films and the release of nonelectrolyte drugs from these films are investigated. It is shown that the nonelectrolyte drugs are unable to modify the chitosan matrix and cannot provide a prolonged drug release. The modification of chitosan–drug films, for example, by isothermal annealing or transition from the salt form of chitosan to the base one, is required to decelerate the release of drugs from the films.     

The estimation of the stability of ionite complexes formed in the sorption of copper cations by weakly alkaline AM-7 anionite

The sorption of copper cations by the complex-forming AM-7 anionite was studied. It was shown that the sorption of copper ions from aqueous solutions was satisfactorily described by the Langmuir equation. The linear approximation to this equation can be used to determine the maximum sorption capacity of the complex-forming anionite. Two independent methods for the determination of the characteristics of the ionite complex (the sorption capacity, stability constant, and coordination number) were considered: the determination of the stability constant from the distribution coefficient and from the data on the destruction of ammonia copper complexes brought in contact with the deprotonated ionite form. In both cases, the calculated stability constants of ionite complexes and the coordination numbers are in satisfactory agreement.     

Sorption of Arsenic Oxyanions from Aqueous Solution on Goethite: a Study of Process Modelling

In the course of researching methods of sampling and monitoring toxic metals (as arsenic ions) in water and wastewaters, we selected the use of sorption for in-depth examination. Among other things, sorption modelling was investigated by the mechanism of surface complexation in order to describe the process or even predict the outcome for the expected rate, and in general, to develop this detection technique for pollutants. This investigation will include the application of goethite mineral as the suitable metal ion sorbent and the use of appropriate computer software. The relative thermodynamic aqueous speciation of the solution, in similar experimental conditions, was also studied.     

Application of Enzymatic Method in the Extraction and Transformation of Natural Botanical Active Ingredients

Active components from traditional Chinese medicine (TCM) are the material basis for disease treatment. Extraction, identification, and transformation are the critical processes to analyze and use the active components of TCM. Botanic TCM takes up 90 % of total Chinese crude drugs. Some active components are complex and of lower level; moreover, most of them are enveloped under plant cell wall. Traditional extraction methods such as lixiviate method, decoction, and others are often hindered by cell wall, leading to low extraction efficiency, low clearance of impurity, and other problems, which have restricted the development of TCM. This paper reviews both domestically and internationally published literatures in recent years on application of enzymatic methods in the extraction and transformation of active ingredients from TCM. Principles of enzymatic method and its application in extraction and transformation of active ingredients and in dreg recycles of TCM are introduced in detail. With the development of TCM modernization, enzymatic method applied in the domain of TCM has achieved prominent benefits, not only improving the extraction and separation rate of active ingredients from TCM and elevating the transformation level and production, but also reducing costs in the transformation of active ingredients.     

Characterisation and improvement of sorption materials with molecular modeling for the use in heat transformation applications

In this paper, several materials for sorption heat transformation applications are evaluated on basis of experimental characterisation and molecular simulation methods. With regard to the application, classical zeolites, ion exchanged zeolites, aluminophosphates as well as silica-aluminophosphates have been analysed. Furthermore samples of metal organic frameworks (MOF) have been evaluated for the use in sorption heat transformation applications with very promising results. In order to understand the fundamental relationship between adsorbent microstructure and water adsorption equilibrium, molecular simulation of water adsorption in various adsorbents are employed. As a result of these simulations within the grand canonical ensemble, the number of water molecules adsorbed in thermodynamic equilibrium under given conditions of temperature and chemical potential (resp. pressure) are obtained. These data are compared with adsorption data from thermogravimetric measurements.     

Mesoporous chromium(<Emphasis Type="SmallCaps">iii</Emphasis>) oxoterephthalate MIL-101: modification and applications

The synthesis and structure of mesoporous chromium(III) oxoterephthalate MIL-101, examples of its functional properties, and various methods of its modification are considered. The potential uses of mesoporous metal-organic framework structures for applications in various areas are analyzed. Particular attention is given to the fundamental questions of gas sorption, catalytic properties of MIL-101, as well as its potential for the development of proton exchange membranes and application in other areas.     

生物膜色谱及其在药物活性成分分析中的应用

介绍了一种新兴的色谱技术-生物膜色谱技术，综述了生物膜色谱技术近十几年的发展状况、生物膜的制备与固定化的各种方法，着重介绍其用于药物与膜相互作用研究的原理及研究成果，并展望了该技术在药物活性成分筛选和活性评价领域的应用前景。     

Preconcentration of Trace Elements in Water for Speciation Studies

Trace element speciation has recently become one of the most important problems in water analysis. Proper combination of preconcentration techniques with instrumental determination methods is essential to speciation analysis, because sensitivity and selectivity of direct determination methods are generally lacking. The present paper describes such preconcentration techniques as filtration, centrifugation, flotation and sorption, which have been developed in the author's laboratory for the speciation of heavy metals in river and pond waters by electron microscopy, X-ray microanalysis and chemical analysis. The application of freeze concentration to the speciation of silica in high-purity waters is also discussed.     

Recent studies of the electrospray ionisation behaviour of selected drugs and their application in capillary electrophoresis-mass spectrometry and liquid chromatography-mass spectrometry

This review is concerned with recent studies of electrospray ionisation-mass spectrometry (ESI-MS) of selected small molecular mass drugs and their application in qualitative and quantitative analytical methods using the techniques liquid chromatography mass spectrometry (LC-ESI-MS) and capillary electrophoresis mass spectrometry (CE-ESI-MS). The publications reviewed are taken from the Web of Knowledge database for the year 2006. The drugs have molecular mass less than 1000 Da and are chosen according to selected drug classifications in which they give ESI signals primarily as [M+H]+ ions. The drug classifications are antibiotics/antibacterials, steroids, anti-tumour drugs, erectile dysfunction agents, anti-epileptic drugs, antiasthmatic drugs, psychoactive drugs and miscellaneous drugs. Details are given on the fragmentations, where available, that these ionic species exhibit in-source and in ion trap, triple quadrupole and time-of-flight mass spectrometers. Analytical methods for the detection and determination of these small molecular mass drug molecules are also discussed, where appropriate, under the particular drug classifications. Analytical information on, for example, sample concentration techniques, separation conditions, recoveries from biological media and limits of detection/quantitation (LODs and LOQs) are provided.     

Water sorption of nails treated with wool keratin proteins and peptides

Water has a considerable effect on human keratin fibres, such as nails, and is therefore crucial for their cosmetic performance. Wool proteins are mild, natural, biodegradable and are sustainably produced with multiple functionalities. They have a potential for use in the cosmetic and detergent markets. The effectiveness of two wool keratin ingredients in restoring the water sorption characteristics of nails was determined. Acetone treatment modified nail water sorption, resulting in an increase in water sorption capacity and in nail permeability. The application of keratin peptides and proteins to healthy and damaged nails improved water sorption properties, reducing permeability, especially in the case of wool keratin protein treatment.