Radiochemical analysis of uranium isotopes in soil and sediment samples with extraction chromatography

An accurate and simple analytical technique for uranium isotopes in highly contaminated soil samples was developed and validated by application to IAEA-Reference samples and environmental samples. For overcoming the demerits of the TBP extraction method, sample materials were decomposited with HNO(3) and HF and uranium isotopes were purified with an anion exchange resin and a TRU Spec resin. With the extraction chromatography method, hindrance elements were completely removed from the uranium fraction. The chemical yields with the extraction chromatography method were <10% higher than those with the TBP extraction method. The concentrations of uranium isotopes using the extraction chromatography method were consistent with the reference values reported by the IAEA.     

Separation and concentration of technetium using a Tc-selective extraction chromatographic resin

For⁹⁹Tc separation from environmental samples, liquid-liquid extraction, ion-exchange chromatography and coprecipitation, have been described. Although these methods are removing matrix elements, some combinations of them is necessary for purification and concentration of Tc. Besides, the procedures are time-consuming and generally a week or more is needed to purify Tc in the samples. In this study, a novel extraction chromatographic resin for the separation and preconcentration of Tc from several kinds of solutions is described. The material is shown to retain Tc efficiently and selectively from these solutions. Sorbed Tc is readily recovered using 5 ml of 12M HNO₃ and the recoveries with^95mTc are more than 97% for all sample solutions.     

Solid-phase extraction sorbent consisting of alkyltrimethylammonium surfactants immobilized onto strong cation-exchange polystyrene resin

Presented is a solid-phase extraction sorbent material composed of cationic alkyltrimethylammonium surfactants attached to a strong cation-exchange resin via ion-exchange. The original hydrophilic cation-exchange resin is made hydrophobic by covering the surface with alkyl chains from the hydrophobic portion of the surfactant. The sorbent material now has a better ability to extract hydrophobic molecules from aqueous samples. The entire stationary phase (alkyltrimethylammonium surfactant) is removed along with the analyte during the elution step. The elution step requires a mild elution solvent consisting of 0.25 M Mg2+ in a 50% 2-propanol solution. The main advantage of using a removable stationary phase is that traditionally utilized toxic elution solvents such as methylene chloride, which are necessary to efficiently release strongly hydrophobic species from SPE stationary phases, may now be avoided. Also, the final extract is directly compatible with reversed-phase liquid chromatography. The performance of this procedure is presented using pyrene as a test molecule.     

Selective solid-phase extraction of catecholamines by the chemically modified polymeric adsorbents with crown ether

A simple and selective one-step solid-phase extraction procedure using chemically modified polymer resin (Amberlite XAD-4) with crown ether was investigated for the measurement of urinary catecholamines. After loading the urine samples (adjusted to pH 4) on the synthesized adsorbent cartridge, the column was washed with methanol followed by water and then the adsorbed catecholamines were eluted by 1.0 mL of 6.0 M acetic acid. The effectiveness of sample clean-up method was demonstrated by reversed-phase ion-pair high-performance liquid chromatography with electrochemical detection. Under optimal condition, the recoveries of epinephrine, norepinephrine, and dopamine from spiked urine sample were >86% for all catecholamines. The detection limits (n=5) for epinephrine, norepinephrine, and dopamine were 37, 52, and 46 nmol/L, respectively.     

Investigation of the solvent extraction of californium, fermium and mendelevium

The extraction constants for the systems di-(2-ethylhexyl)-orthophosphoric acid/toluene/hydrochloric acid and americium, curium californium and fermium have been determined. They have been used to select the best conditions for the separation of californium, fermium and mendelevium by extraction chromatography. The separation factors are much higher than the corresponding ion-exchange methods.     

The thermodynamics of extraction equilibria

A simple graphical method for determination of thermodynamic equilibrium constants, developed for ion-exchange and solvent extraction processes, was successfully applied to a liquid exchangersystem. Close values of the thermodynamic equilibrium constants for the system uranyl chloride—hydrochloric acid—di-2-ethylhyxyl phosphoric acid—toluene (K=7.8±0.8) were obtained when the ionic strength of the aqueous phase was varied and the concentration of di-2-ethylhexyl phosphoric acid in the organic phase was kept constant, and vice versa.     

Sensitive determination of organic acid preservatives in juices and soft drinks treated by monolith-based stir cake sorptive extraction and liquid chromatography analysis

A simple, efficient, and sensitive method for simultaneous determination of sorbic acid (SA), benzoic acid (BA), and cinnamic acid (CA) in juices and soft drinks was developed by stir cake sorptive extraction (SCSE) coupling to high-performance liquid chromatography with diode array detection. The SCSE based on polymeric ionic liquid-based monolith (PILM) as extractive medium was used to concentrate these three organic acid preservatives. Because hydrophobic and ion-exchange interactions co-contributed to the extraction, the PILM-SCSE exhibited a high extractive capability towards analytes. To obtain optimum extraction performance, several SCSE parameters were investigated and discussed, including desorption solvent, pH value, ionic strength in the sample matrix, and the extraction and desorption time. Under the optimized extraction conditions, limits of detection of 0.16, 1.08, and 0.18 μg/L (S/N?=?3) and quantification limits of 0.52, 3.42, and 0.61 (S/N?=?10) were obtained for SA, BA, and CA, respectively. The method also showed good linearity and reproducibility, as well as advantages such as simplicity, low cost, and high feasibility. Finally, the proposed method was successfully applied to the determination of SA, BA, and CA in real juices and soft drinks, and the recoveries ranged from 63.0 to 107 %.     

Solvent extraction clean-up for pre-treatment in amino acid analysis by gas chromatography. Application to age estimation from the D/L ratio of aspartic acid in human dentine

Solvent extraction, a clean-up method for samples for the determination of amino acids by gas chromatography, was investigated and compared with a conventional ion-exchange purification. Amino acids were esterified with isopropanol and extracted with various organic solvents. The solubilities of the amino acid isopropyl esters increased with increasing solvent polarity and the size of the amino acids. The optimum pH was found to be 10.5. The method was applied to the estimation of ages by measurement of the D/L ratio of aspartic acid in human dentine. The D/L ratios so determined were slightly lower than from the ion-exchange method with respect to all dentines examined. However, there were little or no significant differences in the ages estimated by both methods, and the correlation coefficient of this method was 0.982. The method is suitable for the enantiomeric analysis of amino acids, and has several advantages in the technique and time.     

Anion-exchange resin modified with bismuthiol-II, as a new functional resin for the selective collection of selenium(IV)

A functional resin for the collection of selenium(IV) has been prepared simply by the conversion of a common ion-exchange resin with bismuthiol-II which has three functional properties, namely the capabilities of selective reaction with selenium(IV), ion-exchange reaction with ion-exchange resin and strong physical sorption to the ion-exchange resin matrix. The binding ratio of selenium(IV) to bismuthiol-II on the resin was confirmed to be 1:4. The reaction was represented as follows: 4RSH + H(2)SeO(3)--> R-S-Se-S-R + R-S-S-R + 3H(2)O. Highly selective sorption of selenium(IV) was achieved, based on the formation of stable selenotrisulphide on the resin. Selenium(IV) sorbed on bismuthiol-II resin was eluted effectively with 8-13M nitric acid or some thiols, such as cysteine and penicillamine. In the cases of thiols, the elution of selenium was found to be also based on the formation of selenotrisulphide, and the bismuthiol-II resin was regenerated. Satisfactory results were obtained when this resin was applied to the determination of selenium(IV) in river, estuarine or sea water samples.     

Optimization of extraction procedure and chromatographic separation of glyphosate, glufosinate and aminomethylphosphonic acid in soil

Analysing herbicides in soil is a complex issue that needs validation and optimization of existing methods. An extraction and analysis method was developed to assess concentrations of glyphosate, glufosinate and aminomethylphophonic acid (AMPA) in field soil samples. After testing extractions by accelerated solvent extraction and ultrasonic extraction, agitation was selected with the best recoveries. Water was preferred as solvent extraction because it resulted in a cleaner chromatogram with fewer impurities than was the case with alkaline solvents. Analysis was performed by FMOC pre-column derivatization followed by high-performance liquid chromatography (HPLC) on a 300 mm C(18) column which permitted enhanced separation and sensitivity than a 250 mm C(18) column and increased resistance than the NH(2) column for soil samples. This extraction and analysis method allowing a minimum of steps before the injection in the HPLC with fluorescence detection is efficient and sensitive for a clay-loamy soil with detection limits of 103 μg kg(-1) for glyphosate, 15 μg kg(-1) for glufosinate and 16 μg kg(-1) for AMPA in soil samples.     

Microwave-assisted micellar extraction coupled with solid-phase extraction for preconcentration of pharmaceuticals in molluscs prior to determination by HPLC

A simple and specific analytical method was developed and tested for the determination of pharmaceuticals in mollusc samples. A combination of microwave-assisted micellar extraction (MAME) and solid-phase extraction (SPE) using a non-ionic surfactant, polyoxyethylene 10 lauryl ether, was examined to extract and determine simultaneously a group of pharmaceuticals such as carbamazepine, clorfibric acid, ketoprofen, naproxen, bezafibrate and ibuprofen by liquid chromatography using UV-diode array detector. The MAME extraction performance was evaluated by studying various parameters such as the volume and concentration of surfactant and microwave conditions. Finally, an OASIS HLB cartridge was used as an optimum SPE sorbent to clean up the extracts and preconcentrate the selected analytes. The proposed method showed satisfactory linearity and reproducibility (between 3 and 15%), as well as detection limits ranging from 30 to 220 ng/g. Finally, the method was successfully applied to the determination of the target pharmaceuticals in various kinds of mollusc samples. This study has demonstrated that microwave-assisted micellar extraction with solid-phase extraction may be used as a viable alternative to conventional methods for the extraction of pharmaceuticals in this type of matrices.     

Automated trace level determination of glyphosate and aminomethyl phosphonic acid in water by on-line anion-exchange solid-phase extraction followed by cation-exchange liquid chromatography and post-column derivatization.

An automated method based on the on-line coupling of anion-exchange solid-phase extraction (SPE) and cation-exchange liquid chromatography followed by post-column derivatization and fluorescence detection has been developed for the trace level determination of glyphosate and its primary conversion product aminomethyl phosphonic acid (AMPA) in water. PRP-X100 poly(styrene-divinylbenzene)-trimethylammonium anion-exchange cartridges (20 x 2 mm, 10 microm) were selected for the SPE of glyphosate and AMPA. The ionic compounds present in the samples strongly influenced the extraction of both analytes; however, when an on-line ion-exchange clean-up step was introduced before sample SPE, the problem was largely solved. By processing 100-ml samples detection limits better than 0.02 microg/l for glyphosate and 0.1 microg/l for AMPA were achieved in river water. Both analytes were unstable in solution and the approach of storing samples on the PRP-X100 SPE cartridges was evaluated for a period of 1 month under three different storage conditions (deep freeze, refrigeration and 20 degrees C).     

离子交换法分离乳酸的连续流动板模型

本文对乳酸在D354树脂上的离子交换行为进行了详细的研究，并在乳酸的超摩尔离子交换等温线方程的基础上，进一步采用简单的连续流动板模型对乳酸的固定床离子交换行为进行描述，模型拟合结果与实验值能较好的符合。     

Synthesis and properties of strongly basic acrylate polyfunctional anion-exchange resin for uranium extraction

Some studies on the synthesis of strongly basic acrylate polyfunctional anion-exchange resins designed for the extraction of uranium from uranium ore leaching solutions were performed. The alkylation reaction conditions providing the synthesis of a polyfunctional anion-exchange resin with 55% of strongly basic groups were determined. Its sorption properties were studied using model solutions. The capacity of the alkylated polyfunctional anion-exchange resin with respect to uranium was shown to be highly competitive with foreign analogues using the comparative analysis of its ion-exchange characteristics with the parameters of known ion-exchange resins.     

New hydrophilic polymeric resin based on 4-vinylpyridine-divinylbenzene for solid-phase extraction of polar compounds from water

A 4-vinylpyridine-divinylbenzene (VP-DVB) resin was synthesized to be used for on-line solid-phase extraction process and it was tested for a group of polar compounds. The high specific surface area and the nitrogen content of the VP-DVB sorbent increased the interactions with the polar analytes in the preconcentration process. The sorbent enabled 100 ml of water to be concentrated with recoveries higher than 70% for several polar compounds (including phenol) except for oxamyl (55%) and methomyl (43%). The method was used to analyse water samples by liquid chromatography and UV detection. Linearity was good and detection limits were 0.1-0.2 microg l(-1) for all compounds. Several tap and river water and waste water treatment plant samples were analyzed; phenol and (4-chloro-2-methyl-phenoxy)acetic acid (MCPA) were tentatively determined in some samples.     

Fast analysis of relative levels of dehydroabietic acid in papermaking process waters by on-line sample enrichment followed by atmospheric pressure chemical ionisation-mass spectrometry (APCI-MS)

Resin acids are considered to be significant contributors to the toxicity of pulp mill effluents. Traditionally, the analysis of these acids is performed by liquid–liquid extraction followed by gas chromatography. This paper describes a method suitable for monitoring the relative concentration levels of the main resin acid component, dehydroabietic acid (DHAA), in process waters by atmospheric pressure chemical ionisation-mass spectrometry (APCI-MS). This method was further improved, first by testing different precolumns for on-line sample clean-up and then by developing the APCI-MS analysis of the analytes trapped in the precolumn (i.e., solid-phase extraction column). The external standard, internal standard, and response factor methods were compared. The curve profiles of the results obtained with the above determinations were very similar to each other. This finding suggested that the rapid APCI-MS method, using a selected ion monitoring (SIM) technique, is a potential tool for monitoring relative concentration levels of DHAA. The technique is also recommended for rapid and simple monitoring of DHAA as well as of other resin acids, and their derivatives, such as their chlorinated analogues, in various aquatic environmental samples.     

固相萃取-衍生化-气相色谱法测定血液中的3种苯氧羧酸类除草剂

建立了一种血液中2,4-二氯苯氧乙酸(2,4-D)、2-(2,4-二氯苯氧)-丙酸(2,4-DP)和4-氯-2-甲基-苯氧乙酸(MCPA)3种苯氧羧酸类除草剂的分析方法.血样用0.1 mol/L盐酸稀释后用GDX401大孔树脂吸附、用乙醚洗脱,萃取物用二氯丙醇在硫酸催化下进行酯化衍生,衍生物经气相色谱-电子捕获检测.2,4-D、2,4-DP和MCPA的检测限分别为20,8和40 ng/mL.定量分析用2,4-二氯苯乙酸作内标,线性关系和回收率结果均令人满意.     

Weak anion-exchange hypercrosslinked sorbent in on-line solid-phase extraction–liquid chromatography coupling to achieve automated determination with an effective clean-up

A mixed-mode polymeric sorbent was on-line coupled to liquid chromatography (LC) for the first time and applied to the selective solid-phase extract a group of pharmaceuticals in complex environmental water samples. The mixed-mode polymeric sorbent is a high-specific surface area hypercrosslinked polymer resin (HXLPP) in the form of monodisperse microspheres further modified with 1,2-ethylenediamine (EDA) moieties. These properties allow its application as a weak anion-exchange (WAX) sorbent in the on-line solid-phase extraction (SPE) coupling. The on-line SPE-LC method developed using the HXLPP-WAX sorbent was successfully applied to percolate a large volume of ultrapure (500 ml), river (250 ml) and effluent sewage (100 ml) water samples. In all the cases, the HXLPP-WAX resin provided near total recoveries of the most acidic compounds studied and clean chromatograms. This is because the ion-exchange interactions enable a washing step to be added to the SPE protocol that removes the compounds with weak acidic, neutral and basic properties from the sample matrix.     

Rapid method for determination of plutonium, americium and curium in large soil samples

The analysis of actinides in environmental soil and sediment samples is very important for environmental monitoring. There is a need to measure actinide isotopes with very low detection limits. A new, rapid actinide separation method has been developed and implemented that allows the measurement of plutonium, americium and curium isotopes in large soil samples (100–200 g) with high chemical recoveries and effective removal of matrix interferences. This method uses stacked TEVA Resin®, TRU Resin® and DGA-Resin® cartridges from Eichrom Technologies (Darien, IL, USA) that allows the rapid separation of plutonium (Pu), americium (Am), and curium (Cm) using a single multi-stage column combined with alpha-spectrometry. The method combines an acid leach step and innovative matrix removal using cerium fluoride precipitation to remove the difficult soil matrix. This method is unique in that it provides high tracer recoveries and effective removal of interferences with small extraction chromatography columns instead of large ion-exchange resin columns that generate large amounts of acid waste. By using vacuum box cartridge technology with rapid flow rates, sample preparation time is minimized.     

Combined cation-exchange and extraction chromatography for the concomitant separation of Zr, Hf, Th, and the Lanthanides from geological materials

A new method was developed, aiming to overcome the iron and titanium interferences which severely limit the applications of a recently introduced extraction chromatography material, referred to as RE resin (formerly, RE Spec), to the analysis of geological samples. The separation scheme is based on the combined use, in tandem columns, of the conventional AG50WX4 cation-exchange resin and the RE extraction chromatography material, without any intervening evaporation step. The Lanthanides are recovered quantitatively, while recoveries for Zr, Hf and Th range from 94 to 98%. These three elements are determined using the isotope dilution method, thereby alleviating the need for a yield correction. Compared with conventional methods based on cation-exchange, this combined scheme offers a greater multi-element capability, significant miniaturisation, acid wastes reduction, and a higher degree of purity of the separated analytes with regard to unwanted elements such as Ba and residual Ca and Al. This concomitant isolation of 17 trace elements of great interest in the Earth and Environmental Sciences, achieved with excellent recoveries and satisfactory blank levels, can be used prior to high precision analysis of ultra-trace elements in geological samples by ICP-Mass Spectrometry.