Simultaneous determination of trace amounts of borate, chloride and fluoride in nuclear fuels employing ion chromatography (IC) after their extraction by pyrohydrolysis

An accurate and sensitive method based on the combination of pyrohydrolysis-ion chromatography (PH-IC) is proposed for the simultaneous separation and determination of boron as borate, chloride and fluoride in nuclear fuels such as U(3)O(8), (Pu,U)C and Pu-alloys. The determination is based on the initial pyrohydrolytic extraction of B, Cl and F from the samples as boric acid, HCl and HF, respectively, which are subsequently separated by ion chromatography (IC). The proposed method significantly improves the existing analytical methodology as it combines the determination of boron, a critical trace constituent in nuclear materials, along with F(-) and Cl(-) for chemical quality control measurements. Various experimental parameters were optimized to achieve maximum recoveries of the analytes during the pyrohydrolysis and to get better ion chromatographic (IC) separation of borate, F(-) and Cl(-) along with other anions such as CH(3)COO(-), NO(2)(-), NO(3)(-), Br(-), PO(4)(3-) and SO(4)(2-). Recoveries of more than 93% could be obtained for all the analytes in the sample (0.5-1.5 g) at 1200+/-25K and distilled with pre-heated steam at the flow rate of 0.3 mL/min. An isocratic elution with a mobile phase of 0.56 M d-mannitol in 6.5mM NaHCO(3) was used for the IC separation. The detection limits for B (as borate), F(-) and Cl(-) were 24, 13 and 25 microgL(-1), respectively. Precision of about 5% was achieved for determination of boron, Cl(-) and F(-) in the samples containing 1-5 ppm(w) of boron, and 10-25 ppm(w) of Cl and F. The method was validated with reference materials and successfully applied to the nuclear fuels. The methodology is easy to adapt on routine basis.     

On-line solid-phase extraction-ion-pair liquid chromatography-electrospray mass spectrometry for the trace determination of naphthalene monosulphonates in water.

This paper presents an HPLC-MS method for the fully automated determination of a group of naphthalene monosulphonates in environmental water samples. The analytical procedure consisted of on-line ion-pair solid-phase extraction using a PLRP-S precolumn and ion-pair LC separation with triethylamine as ion-pair reagent in both cases. A mass spectrometric detector, coupled to LC through an electrospray interface and operated in negative ion mode, was used. Diagnostic ions usually corresponded to [SO3]- and/or [M-SO2H]- together with [M-H] and/or [M-2H+Na]-. The method was applied to the trace determination of several sulphonates present in tap water, seawater and water from the Ebro river. The analytes were determined at a concentration level between 0.05 and 1 microg l(-1) under selected ion monitoring acquisition by preconcentrating just 15 ml of sample. Naphthalene-1-sulphonate and naphthalene-2-sulphonate were identified and quantified in one of the samples of seawater.     

微波浓缩-离子法测定饮用水中的痕量溴酸根和高氯酸根

 建立了一种简便的用于浓缩水中痕量BrO3 -和ClO4 -的样品前处理方法。水样经OnGuardAg柱过滤 ,用微波炉在 15min内可浓缩 2 0倍 ,所测离子的回收率均高于 90 %。又采用IonPacAS16型亲水性柱 ,用 15 0 μL定量环 ,以NaOH为流动相、梯度淋洗方式 ,在 35min内测定了包括BrO3 -和ClO4 -在内的 8种离子。BrO3 -和ClO4 -的检测限分别为 0 10 μg/L和 0 2 0 μg/L。该方法在实际应用中有较大的参考价值。     

Functionalized-multiwalled carbon nanotubes as a preconcentrating probe for rapid monitoring of cationic dyestuffs in environmental water using AP-MALDI/MS

A simple and sensitive method was developed for the rapid analysis of cationic dyestuffs from river and industrial wastewater using functionalized-multiwalled carbon nanotubes (f-MWCNT) with atmospheric pressure-matrix assisted laser desorption/ionization mass spectrometry (AP-MALDI/MS). The separation and preconcentration of analytes from sample solution was based on electrostatic force of attraction between positive dyestuffs and negatively charged f-MWCNT. The optimum enrichment of the three dyestuffs was observed at pH 5.0 for 3 min contact time and using 1 mg f-MWCNT in 1 mL water sample. The developed method has been successfully applied for the determination of three cationic dyestuffs namely neutral red (NR), brilliant cresyl blue (BB), and methylene blue (MB) in real world samples including river and industrial wastewater. The relative recoveries of dyestuffs from water sample were in the range 88.6-98.4%, indicating that the matrix had little effect on enrichment of analytes. The LOD and LOQ for cationic dyestuffs in water were 0.5-1.9 and 1.6-6.0 microg/L, respectively. All the results indicated that the proposed method could be used for the simultaneous determination of the three cationic dyestuffs in river and industrial wastewater at trace levels without the need of any chromatographic separation techniques.     

Ionic liquid based three-phase liquid-liquid-liquid solvent bar microextraction for the determination of phenols in seawater samples

For the first time, an ionic liquid based three-phase liquid-liquid-liquid solvent bar microextraction (IL-LLL-SBME) was developed for the analysis of phenols in seawater samples. The ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF(6)]), was used as the intermediary solvent for LLL-SBME, enhancing the extraction efficiency for polar analytes. In the procedure, the analytes were extracted from the aqueous sample into the ionic liquid intermediary and finally, back-extracted into an aqueous acceptor solution in the lumen of the hollow fiber. The porous polypropylene membrane acted as a filter to prevent potential interfering materials from being extracted, and no additional cleanup was required. After extraction, the acceptor solution could be directly injected into a high-performance liquid chromatographic system for analysis. Six phenols, 2-nitrophenol, 4-chlorophenol, 2,3-dichlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol were selected here as model compounds for developing and evaluating the method. The most influential extraction parameters were evaluated, including the ionic liquid, the composition of donor solution and acceptor solution, the extraction time and the extraction temperature, the effect of ionic strength, and the agitation speed. Under the most favorable extraction parameters, the method showed good linearity (from 0.05-50 to 0.5-50 μg/L, depending on the analytes) and repeatability of extractions (RSD below 8.3%, n=5). The proposed method was compared to conventional three-phase LLL-SBME and ionic liquid supported hollow fiber protected three-phase liquid-liquid-liquid microextraction, and showed higher extraction efficiency. The proposed method was demonstrated to be a simple, fast, and efficient method for the analysis of phenols from environmental water samples.     

Rapid on-line precolumn high-performance liquid chromatographic method for the determination of benomyl, carbendazim and aldicarb species in drinking water.

A reversed-phase high-performance liquid chromatographic (HPLC) method has been developed for the determination of trace concentrations of benomyl, carbendazim, aldicarb, aldicarb sulphoxide and aldicarb sulphone in drinking water. A 10-ml sample of water is passed through a 3-cm precolumn, packed with 5-microns C8 sorbent, at a flow-rate of 5 ml/min. The HPLC system is then switched to an acetonitrile-water gradient elution program. The preconcentrated analytes are eluted from, and separated by, the 3-cm C8 precolumn and determined by UV absorption. The total analytical time is 25 min. The lowest detectable concentrations are in the range of 2.5 x 10(-9)-11.0 x 10(-9) g/ml for the five analytes investigated with 10 ml of sample.     

High performance liquid chromatography post-column chemiluminescence determination of sulfonamide residues in milk at low concentration levels using bis[4-nitro-2-(3,6,9-trioxadecyloxycarbonyl)phenyl] oxalate as chemiluminescent reagent

The determination of seven sulfonamides by means of HPLC with chemiluminescence detection is proposed for the first time. The analytes are derivatized with fluorescamine, separated and subsequently they participate in the post-column chemiluminescence (CL) peroxyoxalate system using imidazole as a catalyst. Among the different peroxyoxalates tested, bis[4-nitro-2-(3,6,9-trioxadecyloxycarbonyl)phenyl] oxalate provides higher sensitivities and stabilities, avoiding precipitation problems. A rigorous optimization of the significant variables by means of experimental designs has been developed in order to reconcile the chromatographic conditions with the CL reaction. The method provides detection limits in the low microgl(-1) range and has been satisfactorily applied to the analysis of spiked raw milk samples.     

Analysis of tetrabromobisphenol A and other phenolic compounds in water samples by non-aqueous capillary electrophoresis coupled to photodiode array ultraviolet detection

Non-aqueous capillary electrophoresis (NACE) with large-volume sample stacking injection using the electroosmotic flow pump (LVSEP) has been developed for the determination of tetrabromobisphenol A (TBBPA) and other phenolic compounds in environmental matrices. Methanol has been used as run buffer solvent to reduce the electroosmotic flow (EOF). Identification and quantification of the analytes was performed by photodiode array ultraviolet detection. LVSEP-NACE improved sensitivity of the peak height by 90-300-fold. The method developed was applied to the analysis of TBBPA in river water and wastewater samples, using solid-phase extraction (SPE) as sample pretreatment process. The average recoveries of the analytes were in the range of 96-106% and 73-103% for 1 L of river water and 0.5 L of wastewater samples, respectively. When the method was based on off line SPE-LVSEP-NACE, sensitivity was improved by 3300-4500-fold and 1600-2200-fold for river water and wastewater samples, respectively.     

梯度洗脱优化-离子色谱-脉冲安培法分析婴幼儿配方乳粉中的糖和糖醇

建立了梯度洗脱优化-离子色谱-脉冲安培检测技术分析婴幼儿配方乳粉中麦芽糖醇、半乳糖、葡萄糖、蔗糖、果糖、乳糖6种与代谢疾病紧密相关的糖和糖醇的方法。该方法对样品的前处理、色谱柱的选择、淋洗液的梯度等色谱条件进行了优化,重点研究了淋洗液梯度对各组分分离效果的影响。将梯度洗脱程序分解为弱保留组分分离、乳糖分离、基质消除、系统平衡4个子程序,并分别对其进行了条件优化,实现了6种组分的完全分离,并有效解决了弱保留组分色谱峰易重叠、乳糖色谱峰易拖尾等现象。6种组分的线性范围为0.5~100 mg/L,相关系数（r）>0.99,方法的检出限（S/N=3）为0.06~0.40 mg/L。该方法具有分离度好、灵敏度高等优点,可满足例行分析的要求,同时也为淋洗液的梯度优化提供了可借鉴的方法。     

Development of an automated high-performance liquid chromatographic method for the on-line pre-concentration and determination of trace concentrations of pesticides in drinking water

An automated reversed-phase high-performance liquid chromatographic (HPLC) method has been developed for the determination of trace concentrations of propoxur, carbofuran, carbaryl, propham, captan, chloropropham, barban and butylate in drinking water. A 100-ml of sample water is passed through a 3-cm precolumn, packed with 5-microns ODS sorbent, at a flow-rate of 5 ml/min. The HPLC system is then switched to an acetonitrile-water gradient elution program. The analytes, which are concentrated on the precolumn, are eluted and separated on a 25-cm C8 analytical column and determined by measuring the UV absorption at 220 nm. The resolution of analytes is excellent regardless of whether the elution from the precolumn is done unidirectionally or with backflushing. The precolumn can be used repeatedly for at least 30 samples without a significant decrease in efficiency. The total analytical time is 60 min. Tap, distilled, deionized, commercial spring and HPLC-grade waters were analyzed. The lowest detectable concentrations are in the range of 10.10(-12)-460.10(-12) g/ml for the eight pesticides with 100 ml of sample.     

Determination of iodide in seawater samples by ion chromatography with chemically-bonded poly(ethylene glycol) stationary phase

An ion chromatographic method for the rapid and direct determination of iodide in seawater is reported. Poly(ethylene glycol) (PEG) groups were chemically bonded onto silica gel or C30-bonded silica gel via diol groups. PEG-bonded C30 binary phases allowed determination of iodide in seawater samples without any interference. Effects of eluent composition on retention behavior of inorganic anions have been investigated. Both cation and anion of the eluent affected the retention of analyte anions. The retention time of anions increased with increasing eluent concentration. The detection limit for iodide obtained by injecting 0.2 microl of sample was 13 microg l(-1) (S/N=3) while the limit of quantitation was 43 microg l(-1) (S/N=10). The present method was successfully applied to the rapid and direct determination of iodide in seawater with long-term durability.     

Determination of halogenated mono-alcohols and diols in water by gas chromatography with electron-capture detection

We have developed an analytical method for the detection of halogenated alcohols in water with particular focus on 3-chloro-1,2-propanediol and 3-bromo-1,2-propanediol. In this method the target analytes are extracted from water, derivatized with heptafluorobutyric anhydride, and then analyzed with gas chromatography with electron-capture detection. The effects of water, pH and seawater constituents on the method were investigated. Method detection limits for a 5 ml aqueous sample ranged from 0.14 microg l(-1) for 2-bromo-1,3-propanediol to 1.7 microg l(-1) for 1,3-dichloro-2-propanol (1,3DCP).     

Effect of Surfactant Loading on the Extraction Properties of C-18 Bonded Silica used for Solid-Phase Extraction of Phenols

ABSTRACT

A solid phase extraction (SPE) system has been modified with cationic surfactants and evaluated for extraction and preconcentration of trace phenolic compounds contaminants in water at low ppb concentrations. Cationic surfactants such as cetyl trimethyl ammonium bromide (CTAB) has been steadily adsorbed on the surface of C-18 bonded silica, and the ionized functional group of the surfactant can then act as an ion–exchange site to attract the ionized phenolic compounds from water samples. The method includes enrichment of the phenolic compounds by the surfactant-loaded solid phase extraction system, followed by elution of the analyte with methylene chloride and derivatization of the phenolic compounds with acetic anhydride. Thirty-two phenolic analytes were identified and quantitatively determined by this method; identification and quantification of the compounds is performed with GC/FID using 2-bromophenol as internal standard. SPME analysis with this method was linear over 3-6 orders of magnitude, with linear correlation coefficient (R²) greater than 0.96. Experimentally determined FID detection limits ranged from ～30 ppt for methyl-substituted phenols to ～0.1ppb for phenol and chloro-substituted phenols. We tested the influence of sample pH, the loading amount of surfactant on the solid phase, and the volume and matrixes of the sample were studied. Absolute recoveries from pure water spiked with 0.2 ppb phenolic compounds were 96 – 103%. The method has been applied to analysis of various natural waters, including ground water, lake water, seawater, and wastewater. Recoveries from ground water, lake water, seawater, and wastewater were 92 – 106%, 75 – 93%, 87 – 103%, 86 – 99%, respectively. Therefore, the new technique proved to be an excellent tool for trace enrichments of phenolic compounds at low ppb concentration of these analytes, from different natural water samples.     

Understanding mechanisms of pressure-assisted electrokinetic injection: application to analysis of bromate, arsenic and selenium species in drinking water by capillary electrophoresis-mass spectrometry

The mechanism underlying the enrichment power by pressure-assisted electrokinetic injection (PAEKI) in capillary electrophoresis (CE) was investigated for on-line pre-concentration of arsenic [As(III) and As(V)], selenium [Se(IV) and Se(VI)] and bromate (BrO(3)(-)). Analyte diffusion behaviour from PAEKI sample plugs were evaluated by monitoring peak broadening as a function of stagnant time and position in the capillary. During PAEKI, anionic analytes accumulate at the sample-separation buffer boundary. We proposed that a counter-ion layer formed in PAEKI, where a cation layer was formed at the separation buffer side of boundary. The cation layer served as a soft boundary which impeded zone broadening via electrostatic attraction between layers. This effect likely played an important role in maintaining focused analyte bands by suppressing diffusion. Comparison of analyte behaviour in PAEKI injected sample plugs to behaviour in hydrodynamically injected ones proved the existence of a counter-ion layer. The dependence of analyte diffusion in PAEKI plugs on electrochemical properties (viscosity, conductivity, electrophoretic mobility) further supported the hypothesis. Additionally, it was noted that analytes with low electrophoretic mobility were more efficiently pre-concentrated by PAEKI and were less subject to forces of dispersion than analytes with greater electrophoretic mobility. PAEKI-CE coupled to electrospray tandem mass spectroscopy (ESI-MS/MS) was then optimized and validated for detection of arsenic, selenium and bromate in water samples. On-line enrichment of the target analytes was achieved with 1-3 ng mL(-1) detection limits, which was below the maximum contaminant levels in drinking water for all five anions studied. Noteworthy, the potential of the method for unbiased detection of molecular species in untreated water was demonstrated. No contamination was detected in the water samples tested; however, recovery was 90-118% for spiked samples. The method was demonstrated be comparable to current methods for detection of inorganic contaminants in drinking water and is a good alternative method to ion chromatography/liquid chromatography-MS.     

Photoacoustic spectroscopic studies on the solid phase cell with a differential type microphone using a diode laser as radiation source

The design and applications of the solid phase photoacoustic cell with a differential type microphone are described. This cell has higher sensitivity and reproducibility relative to a cell without a differential microphone. The method has been applied to the determination of phosphate ion in water samples. The detection limit for phosphate ion concentrated from 22.5 ml of sample solution on a membrane filter as molybdophosphate-n-dodecyltrimethylammonium bromide was 3.0 ng PO(3-)(4)/ml and the coefficient of variation for five measurements at 20 ng PO(3-)(4)/ml of phosphate ion was 3% using a diode laser (30 mW, 826 nm) as radiation source. The calibration graph for phosphate ion was linear over the range 5-50 ng PO(3-)(4)/ml.     

Selective enrichment of U(VI), Th(IV) and La(III) from high acidic streams using a new chelating ion-exchange polymeric matrix

An off-line extraction chromatographic technique has been developed using Amberlite XAD-16 (AXAD-16)-N,N-dihexylcarbamoylmethyl phosphonic acid, as the stationary phase for the extraction of uranium, thorium and lanthanum from nuclear spent fuels as well as from geological and natural water resources. The chemical modifications of the polymeric matrix were monitored using FT-IR spectroscopy, CHNPS elemental analysis and also by thermo gravimetric analysis for water regain measurements. Various physio-chemical parameters influencing the quantitative metal ion extraction by the resin phase were optimized by both static and dynamic methods. The developed resin matrix showed good distribution ratio values under wide concentrations of acidity and pH conditions. Moreover, the sequential separation of analytes is also possible at sample pH 6.5. Also, the polymeric matrix showed superior metal sorption capacities and rapid metal exchange kinetics with a high sample flow rate value of 26 cm³ min⁻¹ for all the three analytes. Thus, reducing the time of analyte extraction from large number of samples anticipated in nuclear waste management programs. The quantitative metal ion recovery of >99.8% was effected with 0.5 M (NH₄)₂CO₃ solution. The method was highly sensitive with lower limits of detections to be 10, 20 and 15 ng cm⁻³ for U(VI), Th(IV) and La(III), respectively, with a better pre-concentration values of 333 for U(VI) and Th(IV) and 400 for La(III), respectively paving way for its applicability in pre-concentrating trace analytes from large sample volumes. The analytical data were within 4.2% R.S.D. reflecting the reproducibility and reliability of the developed method.     

Chiral supercritical fluid chromatography/tandem mass spectrometry for the simultaneous determination of pindolol and propranolol in metabolic stability samples

A chiral packed-column supercritical fluid chromatographic (pSFC) system coupled to tandem mass spectrometer (MS/MS) for the rapid measurements of (R,S)-propranolol and (+/-)-pindolol in metabolic stability samples was developed. The effects of the eluent flow rates and compositions, as well as of the nebulizer temperature, on the chromatographic performance and the ionization efficiency of the analytes in positive ion mode under pSFC conditions were studied. The ionization mechanism of the analytes in the CO2/methanol atmospheric pressure chemical ionization (APCI) environments with or without the use of an additive was studied. The chiral pSFC-APCI-MS/MS approach requiring approximately 2 min per sample was applied for the simultaneous determination of two pairs of racemic drugs in in vitro samples at low nanogram per milliliter concentrations.     

Determination of glyphosate and phosphate in water by ion chromatography--inductively coupled plasma mass spectrometry detection

Quantitative determination of trace glyphosate and phosphate in waters was achieved by coupling ion chromatography (IC) separation with inductively coupled plasma mass spectrometry (ICP-MS) detection. The separation of glyphosate and phosphate on a polymer anion-exchange column (Dionex IonPac AS16, 4.0 mm x 250 mm) was obtained by eluting them with 20 mM citric acid at 0.50 mL min(-1), and the analytes were detected directly and selectively by ICP-MS at m/z = 31. Parameters affecting their chromatographic behaviors and ICP-MS characteristics were systematically examined. Based on a 500-microL sample injection volume, the detection limits were 0.7 microgL(-1) for both glyphosate and phosphate, and the calibrations were linear up to 400 microgL(-1). Polyphosphates, aminomethylphosphonic acid (the major metabolite of glyphosate), non-polar and other polar phosphorus-containing pesticides showed different chromatographic behaviors from the analytes of interest and therefore did not interference. The determination was also interference free from the matrix anions (nitrate, nitrite, sulphate, chloride, etc.) and metallic ions. The analysis of certified reference material, drinking water, reservoir water and Newater yielded satisfactory results with spiked recoveries of 97.1-107.0% and relative standard deviations of < or = 7.4% (n = 3). Compared to other reported methods for glyphosate and phosphate, the developed IC-ICP-MS method is sensitive and simple, and does not require any chemical derivatization, sample preconcentration and mobile phase conductivity suppression.     

On-line trace enrichment for the simultaneous determination of microcystins in aqueous samples using high-performance liquid chromatography with diode-array detection.

The need for a rapid, sensitive and reliable analytical method for cyanobacterial toxins, microcystins, has been emphasized by the awareness of toxic cyanobacteria as a human-health risk through drinking water. A new high-performance liquid chromatographic method with column switching was developed for the determination of microcystin-LR, -RR and -YR from water samples without pre-purification. The filtered water sample was passed through a Zorbax CN precolumn at a flow-rate of 3 ml/min for on-line trace enrichment. After valve switching, concentrated analytes were eluted in back-flush mode and separated on a Luna C18 column with a gradient of acetonitrile -20 mM phosphate buffer (pH 2.5). The method showed excellent precision, accuracy and speed with detection limits of 0.02 microgram/ml from 100 ml of surface water. The total analysis time per sample was about 90 min. This method improves reliability, sensitivity and sample throughput, and shortens the analysis time compared to analysis methods using off-line solid-phase extraction.     

Gas-phase coordination complexes of dipositive plutonyl, PuO2(2+): chemical diversity across the actinyl series

We report the first transmission of solvent-coordinated dipositive plutonyl ion, Pu(VI)O(2)(2+), from solution to the gas phase by electrospray ionization (ESI) of plutonyl solutions in water/acetone and water/acetonitrile. ESI of plutonyl and uranyl solutions produced the isolable gas-phase complexes, [An(VI)O(2)(CH(3)COCH(3))(4,5,6)](2+), [An(VI)O(2)(CH(3)COCH(3))(3)(H(2)O)](2+), and [An(VI)O(2)(CH(3)CN)(4)](2+); additional complex compositions were observed for uranyl. In accord with relative actinyl stabilities, U(VI)O(2)(2+) > Pu(VI)O(2)(2+) > Np(VI)O(2)(2+), the yields of plutonyl complexes were about an order of magnitude less than those of uranyl, and dipositive neptunyl complexes were not observed. Collision-induced dissociation (CID) of the dipositive coordination complexes in a quadrupole ion trap produced doubly- and singly-charged fragment ions; the fragmentation products reveal differences in underlying chemistries of plutonyl and uranyl, including the lower stability of Pu(VI) as compared with U(VI). Particularly notable was the distinctive CID fragment ion, [Pu(IV)(OH)(3)](+) from [Pu(VI)O(2)(CH(3)COCH(3))(6)](2+), where the plutonyl structure has been disrupted and the tetravalent plutonium hydroxide produced; this process was not observed for uranyl.