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1.
The sensitivity of on-line vapor generation atomic absorption spectrometry of mercury and selenium was improved by using a new atom trap technology. The inner wall of a T-shaped quartz tube was coated with nanometer SiO2 so increase the residence time of the analyte atoms in the light path. The linear range of the calibration plots thus was increased to a range from 5.0 to 150 ng mL?1 for mercury, and from 4.5 to 100 ng mL?1 for selenium. The detection limits are 0.9 ng mL?1 for Hg and 1.0 ng mL?1 for Se which is a 2-fold improvement. The technique was applied to the determination of Hg and Se in herbs and hair. 相似文献
2.
Qingyang Liu 《Mikrochimica acta》2009,167(1-2):141-145
An on-line nano-TiO2 controlled volatilization system was developed for inorganic selenium speciation based on the irradiation of thiourea with ultraviolet light. It provides an effective hyphenation unit for atomic fluorescence spectrometry. The effects of several factors such as the acidity, the concentration of thiourea, the amounts of TiO2, the concentration of KBH4 and the flow rates of carrier gas were investigated. Under optimal conditions, the limit detections for Se(IV) and Se(VI) were 2.38 and 3.39 ng mL?1 (100?µL injection, 3 times of the baseline noise), respectively. The relative standard for deviations of 50 ng mL?1 Se(IV) and Se(VI) were 3.7% and 2.7%, respectively. The method has been applied for determination of inorganic selenium species in real samples and the recoveries were between 93% and 98%. 相似文献
3.
Speciation analysis of selenium enriched green onions (Allium fistulosum) by HPLC-ICP-MS 总被引:1,自引:0,他引:1
Green onions (Allium fistulosum) enriched with 10 or 100 μg mL− 1 Se(IV) or SeMet were analyzed for total selenium and species distribution. Anion and cation exchange chromatographies were applied for the separation of selenium species with mass spectrometric detection. Two different sample preparation methods (NaOH and enzymatic) were compared from the Se extraction efficiency point of view. Total selenium concentration accumulated by the onions reached the 200 μg g− 1 level expressed for dry weight when applying SeMet at a concentration of 100 μg mL− 1 as the source of Se. Speciation studies revealed that both in onion bulbs and leaves the predominant form of organic selenium is Se-methyl-selenocysteine (MeSeCys). When Se(IV) was applied for Se-enrichment at a concentration level of 100 μg mL− 1 both onion leaf and bulb contained a significant amount of inorganic selenium. An unknown compound was also detected. 相似文献
4.
A method for the determination of iodate was developed by reversed-phase high-performance liquid chromatography with UV detection. Iodate was converted to iodine, which was separated from the matrix using a reversed-phase Ultrasphere C18 column (250 × 4.6 mm, 5 μm) with methanol-1 mmol L?1 H3PO4 (20:80, v/v) as mobile phase at 1.00 mL min?1 and UV detection at 224 nm. The calibration graph was linear from 0.05 μg mL?1 to 5.00μg mL?1 for iodine with a correlation coefficient of 0.9994 (n=7). The detection limit was 0.01 μg mL?1. The method was successfully applied to the determination of iodate in iodized salt. The recovery was from 96% to 101% and the relative standard deviation was in the range of 1.5% to 2.9%. 相似文献
5.
The accuracy of the determination of selenium in human body fluids by hydride-generation a.a.s. depends critically upon the sample decomposition-method used. Digestion with HNO3 alone gave low selenium recoveries, but with nitric, sulfuric and perchloric acids at a final temperature of 310°C gave results that agreed with those obtained by other techniques. The recovery of selenomethionine added to whole blood and of trimethylselenonium iodide added to urine was 97–104%. The average selenium values found for 6 healthy individuals were 88 μg l?1 in whole blood, 75 μg l?1 in blood plasma and 307 μg (kg Hb)?1 in erythrocytes. A detection limit of 5 μg l?1 Se in body fluids was found under routine conditions. 相似文献
6.
D. Kostova 《Russian Journal of Inorganic Chemistry》2012,57(12):1593-1598
The system manganese(VII)-3,7-bis(dimethylamino)-phenothiazin-5-ium chloride (MB)-water-1,2-dichloroethane has been studied using UV-spectrophotometry. The molar absorptivity of the complex is (3.86 ± 0.06) × 104 L mol?1 cm?1 at 290 nm and the system obeys Beer??s law in the range 0.1?C0.99 ??g mL?1 Mn(VII). The detection limit (DL) and quantitation limit (QL) of Mn(VII) determination were found to be 0.0146 and 0.049 ??g mL?1, respectively. The composition of the complex is established as MB: MnO 4 ? = 1: 1. Extraction investigations of the system discussed were carried out. The characteristic values for the extraction equilibrium and the equilibrium in the aqueous phase was determined: extraction constant Kex = (1.12 ± 0.05) × 105, distribution constant KD = 75.61 ± 0.1 and association constant ?? = (1.48 ± 0.08) × 103. A new method has been developed for the microdetermination of manganese(VII) in plants and steels. 相似文献
7.
M. Eva Moreno Riansares Muñoz Concepción Perez-Conde Carmen Cámara 《International journal of environmental analytical chemistry》2013,93(3-4):413-426
Abstract This paper reports for the first time a suitable way to determine methylated selenium compounds using the new approach of pervaporation coupled to atomic fluorescence spectrcmetry (PV-AFS). The method developed allows direct extraction, separation, preconcentration and determination of dimethylselenium (DMSe) and dimethyldiselenium (DMDSe) from slurry samples. Under the optimum conditions, the detection limits (LODs) were found to be 0.66 ng and 0.39 ng for DMSe and DMDSe, respectively, the precision being about 6–9 % for 10 ng mL as selenium concentration. The linearity ranges were from the LOD to 0.7 μg mL?1 for DMSe and from the LOD to 0.4 μg mL?1 for DMDSe (as Se). The pervaporation efficiencies were 55 ± 1 % and 85 ± 5 % for DMSe and DMDSe, respectively. The proposed method was successfully applied to determine methylated selenium species in sewage sludge, garlic and oyster samples. The concentrations found were from 0.07 to 1.42 μg g?1. As no certified reference materials are available for these analytes, validation was carried out by recovery studies in these matrices, and the results showed that the proposed method performed satisfactorily. 相似文献
8.
(Molecular absorption spectrometry with electrothermal vaporization in a graphite cuvette. Part 12. Determination of chloride species in selenium and AIIIBV-semiconductor materials after separation of the traces by adsorptive precipitation and distillation.) The determination of traces of chloride in chloride-dosed selenium and in gallium arsenide by molecular absorption spectrometry of AlCl is described. The traces of chloride are separated by adsorption precipitation (AgCl/Al2O3). The AgCl is dissolved in ammonia. After addition of Al3+ and Ba(OH)2 the molecular absorption of AlCl is measured at 261.4 nm. It is possible to determine 0.2 μg g?1 Cl in 500 mg of Se or GaAs. 相似文献
9.
《Electroanalysis》2005,17(17):1511-1515
Differential pulse voltammetric determination of selenocystine (SeC) using selenium‐gold film modified glassy carbon electrode ((Se‐Au)/GC) is presented. In 0.10 mol?L?1 KNO3 (pH 3.20) solution, SeC yields a sensitive reduction peak at ?740 mV on (Se‐Au)/GC electrode. The peak current has a linear relationship with the concentration of SeC in the range of 5.0×10?8–7.0×10?4 mol?L?1, and a 3σ detection limit of SeC is 3.0×10?8 mol?L?1. The relative standard deviation of the reduction current at SeC concentration of 10?6 mol?L?1 is 3.88% (n=8) using the same electrode, and 4.19% when using three modified electrodes prepared at different times. The content of SeC in the selenium‐enriched yeast and selenium‐enriched tea is determined. The total selenium in ordinary or selenium‐enriched tea is determined by DAN fluorescence method. The results indicate that in selenium‐enriched yeast about 20% of total selenium is present as SeC and in selenium‐enriched tea SeC is the major form of selenoamino acids. The total selenium content in selenium‐enriched tea soup is 0.09 μgSe/g accounting by 7% compared with that in selenium‐enriched tea. Hence, only a little amount of selenium is utilized by drinking tea, and most selenium still stay in tealeaf. Uncertainty are 22.4% and 16.1% for determination of SeC in selenium‐enriched yeast and selenium‐enriched tea by differential pulse voltammetry (DPV) on (Se‐Au)/GC electrode, respectively. 相似文献
10.
The seleno‐bis (S‐glutathionyl) arsinium ion, [(GS)2AsSe]?, which can be synthesized from arsenite, selenite and glutathione (GSH) at physiological pH, fundamentally links the mammalian metabolism of arsenite with that of selenite and is potentially involved in the chronic toxicity/carcinogenicity of inorganic arsenic. A mammalian metabolite of inorganic arsenic, dimethylarsinic acid, reacts with selenite and GSH in a similar manner to form the dimethyldiselenoarsinate anion, [(CH3)2As(Se)2]?. Since dimethylarsinic acid is an environmentally abundant arsenic compound that could interfere with the mammalian metabolism of the essential trace element selenium via the in vivo formation of [(CH3)2As(Se)2]?, a chromatographic method was developed to rapidly identify this compound in aqueous samples. Using an inductively coupled plasma atomic emission spectrometer (ICP‐AES) as the simultaneous arsenic‐ and selenium‐specific detector, the chromatographic retention behaviour of [(CH3)2As(Se)2]? was investigated on styrene–divinylbenzene‐based high‐performance liquid chromatography (HPLC) columns. With a Hamilton PRP‐1 column as the stationary phase (250 × 4.1 mm ID, equipped with a guard column) and a phosphate‐buffered saline buffer (0.01 mol dm?3, pH 7.4) as the mobile phase, [(CH3)2As(Se)2]? was identified in the column effluent according to its arsenic:selenium molar ratio of 1 : 2. With this stationary phase/mobile phase combination, [(CH3)2As(Se)2]? was baseline‐separated from arsenite, selenite, dimethylarsinate, methylarsonate and low molecular weight thiols (GSH, oxidized GSH) that are frequently encountered in biological samples. Thus, the HPLC–ICP‐AES method developed should be useful for rapid identification and quantification of [(CH3)2As(Se)2]? in biological fluids. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
11.
We describe a method for the determination of inorganic selenium in water samples via gas-phase chemiluminescence (GPCL). Se(IV) was first derivatized with 4-nitro-o-phenylenediamine to form 5-nitropiazselenol. The latter was decomposed by persulfate through photocatalytic oxidation to give Se(VI), which was reduced to Se(IV). Selenium hydride was generated from Se(IV) through reduction with sodium borohydride and then preconcentrated using cryotrapping. The cryotrapped hydride was evaporated and carried to a reaction chamber by a stream of helium, where it produced GPCL as a result of ozonation. The method exhibits a wide linear calibration range (from 0.5?μg?L?1 to 1.0?mg?L?1) with a detection limit of 0.12?μg?L?1 (for n?=?11), and a relative standard deviation of 3.90?% (at n?=?11) at 5.0?μg?L?1 level of selenium. The method was applied to the determination of inorganic selenium in water samples and gave satisfactory results. Figure
A GPCL detection system is developed for the determination of inorganic selenium in water samples. By using analytical technique in this figure, such as derivatization, UV/ S2O 8 2- decomposition, stopped-flow injection and cryotrapping, the system can separate and preconcentrate the analyte from the matrix, then produce GPCL as a result of ozonation. The method was simple, sensitive with low-cost instrumentation. 相似文献
12.
A simple and robust flow injection system which permits low sample and reagent consumption is described for rapid and reliable hydride generation atomic absorption spectrometric determination of selenium, arsenic and bismuth. The system, which composed of one peristaltic pump and one four channel solenoid valve, used water as the carrier streams for both sample and NaBH4 solution. Rapid off-line pre-reduction of the analytes was achieved by using hydroxylamine hydrochloride for selenium and a mixture of potassium iodide and ascorbic acid for arsenic and bismuth. Transition metal interference was eliminated with the addition of thiourea and EDTA into the NaBH4 solution and significant sensitivity enhancement was observed for selenium in the presence of thiourea in the reductant solution. Under optimised conditions, the method achieved detection limits of 0.2 ng mL−1 for Se, 0.5 ng mL−1 for As and 0.3 ng mL−1 for Bi. The method was very reproducible, achieving relative standard deviations of 6.3% for Se, 3.6% for As and 4.7% for Bi, and has a sample throughput of 360 h−1. Successful application of the method to the quantification of selenium, arsenic and bismuth in a certified reference river sediment sample is reported. 相似文献
13.
A sensitive catalytic method for determining ng ml? concentration of selenium is described. The method is based on the catalytic action of Se(IV) on the reduction of resazurin by sulphide, monitored spectrophotometrically at 605 nm. The linearity range of the calibration graph is dependent on the concentration of sulphide. The variables affecting the rate of the reaction were investigated and the optimum conditions were established. The method is simple, rapid, precise, sensitive and widely applicable. As low as 8.0 × 10?4 μg ml?1 of selenium can be determined. The relative standard deviation of seven determination of 10 ng Se was 0.7%. The determination of Se(IV) in the presence of Se(VI) and the determination of total selenium are also described. 相似文献
14.
In this work, determination of selenium in various water samples was done by using hydride generation atomic absorption spectrometry. The most appropriate values of HCl concentration, NaBH4 concentration, NaOH concentration, flow rate of argon and flow rate of waste solution were determined. The optimum concentration of the HCl, NaBH4 and NaOH solutions were found to be 7.0 mol L?1, 1.0% and 0.75%, respectively. The optimum flow rate of Ar gas and waste solution were also found to be 100.9 mL min?1 and 4.0 mL min?1, respectively. Values of LOD and LOQ were calculated separately for total Se and Se(IV). LOD and LOQ values were calculated 0.56 μg L?1, 1.87 μg L?1 for total Se and 0.72 μg L?1, 2.40 μg L?1 for Se(IV), respectively. The precision was evaluated by relative standard deviation (RSD%) was found to be 3.5% for total Se and 3.1% for Se(IV) (n = 11). A standard reference material (NIST 1643e) was used in order to check the accuracy of the proposed method. There was a good agreement between certified and found values for standard reference material. The method was applied to the analysis of total Se and Se(IV) concentrations in tap water samples collected from the various regions of Mu?la. Proposed method showed spike recovery ranges from 92% to 116% in water samples. 相似文献
15.
Nadja F. G. Serrano Ligia Rodrigues Carlos O. Hokka Cristina P. Sousa José A. Teixeira Solange I. Mussatto 《Chemical Papers》2012,66(12):1111-1117
The production of antimicrobial metabolites by Paenibacillus polymyxa RNC-D was assessed. Two process variables, glucose and inoculum concentrations, were evaluated at different levels (5?C40 g L?1, and at ?? r = 2.5?C5.0 %, respectively), and their effects on biomass formation, minimal inhibitory concentration (MIC) against Escherichia coli, and surface tension reduction (STR) were studied. When the fermentation process was carried out under non-optimised conditions, the biomass, MIC, and STR achieved the following values: 0.6 g L?1, 1 g L?1, and 18.4 mN m?1, respectively. The optimum glucose (16 g L?1) and inoculum volume ratio (?? r = 5.0 %) were defined in order to maximise the biomass formation, with a low value of MIC and high STR of extract. The experiments carried out under optimal conditions showed the following values for the dependent variables: biomass concentration 2.05 g L?1, MIC 31.2 ??g mL?1, and STR 10.7 mN m?1, which represented improvement of 241.7 %, 96.9 %, and 41.9 % for the responses of biomass, MIC, and STR, respectively. This is the first recorded study on the optimisation of culture conditions for the production of antimicrobial metabolites of P. polymyxa RNC-D, and constitutes an important step in the development of strategies to modulate the production of antimicrobial molecules by this microorganism at elevated levels. 相似文献
16.
Mohammad S. El-Shahawi Abdelhameed M. Othman Abdulaziz S. Bashammakh Mervat A. El-Sonbati 《International journal of environmental analytical chemistry》2013,93(12):941-954
The chromogenic reagent 4,4′-dichloro(3-mercapto-1,5-diphenylformazan), Cl2H2D Z , forms a yellow–red-coloured complex with selenium(IV). The produced complex species was extracted quantitatively into n-hexane, and its absorbance was measured at 416?nm. The chemical composition of the extracted selenium(IV)-Cl2H2D Z chelate and the molar absorptivity at 416?nm were found to be [SeO (Cl2HD Z )2] and 9?×?104?L?mol?1?cm?1, respectively. The values of the extraction constants (K D, K ex, β) enable a convenient application of the proposed system for the liquid–liquid extraction procedure and sequential spectrophotometric determination of traces of inorganic selenium(IV) and/or selenium(VI) after reduction of the later to selenium(IV) with HCl (6?M). Beer's law and Ringbom's plots were obeyed in the concentration range 0.01–20 and 0.5–19?µg?mL?1 of selenium(IV), respectively, with a relative standard deviation of 2.2%. The proposed method has been successfully applied to the determination of selenium(IV) or (VI) and total inorganic selenium(IV) and (VI) in tap and freshwater samples. 相似文献
17.
Wulin Yang Ying Gao Li Wu Xiandeng Hou Chengbin Zheng Xiaofan Zhu 《Mikrochimica acta》2014,181(1-2):197-204
We have developed a method for the determination of trace levels of total selenium in water samples. It integrates preconcentration, in-situ photoreduction and slurry photochemical vapor generation using TiO2 nanoparticles, and the determination of total selenium by AFS. The Se(IV) and Se(VI) species were adsorbed on a slurry of TiO2 nanoparticles which then were exposed to UV irradiation in the presence of formic acid to form volatile selenium species. The detection limits were improved 17-fold compared to hydride generation and 56-fold compared to photochemical vapor generation, both without any preconcentration. No significant difference was found in the limits of detection (LODs) for Se(IV) and Se(VI). The LOD is as low as 0.8 ng L?1, the precision is better than 4.5 % (at a level of 0.1 μg L?1 of selenium). The method gave good recoveries when applied to the determination of total selenium in a certified tissue reference material (DORM-3) and in spiked drinking water and wastewater samples containing high concentrations of transition and noble metal ions. It also excels by very low LODs, a significant enhancement of sample throughput, reduced reagent consumption and sample loss, and minimal interference by transition and noble metal ions. Figure
A method integrating pre-concentration, in situ photo-reduction and slurry photochemical vapor generation by using TiO2 nanoparticles was developed for sensitive determination of total selenium in various water samples by atomic fluorescence spectrometry. 相似文献
18.
A new reagent system using rhodamine‐B dye for the determination of selenium is described. The method is based on the reaction of selenium with acidified potassium iodide to liberate iodine. The liberated iodine bleaches the pink colour rhodamine‐B, which is measured at 555 nm. Beer's law is obeyed over the concentration range of 1–10 μg of selenium final solution volume of 25 mL (0.04–0.4 ppm) and the apparent molar absorptivity and Sandell's sensitivity was found to be 1.96× 105 l mol?1 cm?1 and 0.0004 μg cm?2, respectively. The method is simple, sensitive, and selective and is satisfactorily applied to micro‐level determination of selenium in various environmental and cosmetic samples. 相似文献
19.
Calix[4]pyrrole-based Crosslinked Polymer Networks for Highly Effective Iodine Adsorption from Water
Linhuang Xie Zhiye Zheng Qiuyuan Lin Huan Zhou Xiaofan Ji Jonathan L. Sessler Hongyu Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2022,134(1):e202113724
A series of calix[4]pyrrole-based crosslinked polymer networks designed for iodine capture is reported. These materials were prepared by Sonogashira coupling of α,α,α,α-tetra(4-alkynylphenyl)calix[4]pyrrole with bishalide building blocks with different electronic properties and molecular sizes. Despite their low Brunauer–Emmett–Teller surface areas, iodine vapor adsorption capacities of up to 3.38 g g?1 were seen, a finding ascribed to the presence of a large number of effective sorption sites including macrocyclic π-rich cavities, aryl units, and alkyne groups within the material. One particular system, C[4]P-BTP , was found to be highly effective at iodine capture from water (uptake capacity of 3.24 g g?1 from a concentrated aqueous KI/I2 solution at ambient temperature). Fast capture kinetics (kobs=7.814 g g?1 min?1) were seen. Flow-through adsorption experiments revealed that C[4]P-BTP is able to remove 93.2 % of iodine from an aqueous source phase at a flow rate of 1 mL min?1. 相似文献
20.
G. M. Sergeev E. V. Shlyapunova M. A. Pozdnyakova 《Journal of Analytical Chemistry》2007,62(5):416-423
A procedure is proposed for the selective extraction-photometric determination of the acid-forming elements S(IV), Se(IV), Te(IV), and As(III) in their mixtures containing molecular forms or anions with different electron densities on donor atoms. The procedure is based on the difference in the oxidizability of analytes with the [SbCl6]? complex. The analytical ranges are found at different pHs of the medium, affecting the potential of the two-phase redox systems. The detection limits for sulfite, selenite, tellurite, and arsenite are 1 × 10?3, 5 × 10?5, 7 × 10?5, and 1 μg/mL, respectively. The procedure is applied to the determination of selenium in H2SO4 of high-purity grade, which is used in the production of microelectronics items and in some agricultural samples. The error of analysis is no worse than 20%. 相似文献