首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
李勋  汪正浩 《中国化学》2007,25(3):295-299
A new direct procedure for the determination of inorganic arsenic species was developed by electrochemical hydride generation atomic absorption spectrometry (EcHG-AAS) with selective electrochemical reduction. The determination of inorganic arsenic species is based on the fact that As(Ⅲ) shows significantly higher absorbance at low electrolytic currents than As(Ⅴ) in 0.3 mol·L^-1 H2SO4. The electrolytic current used for the determination of As(Ⅲ) without considerable interferences of As(Ⅴ) was 0.4 A, whereas the current for the determination of As(Ⅲ) and As(Ⅴ) was 1.2 A. For equal concentrations of As(Ⅲ) and As(Ⅴ) in a sample, the interferences of As(Ⅴ) during the As(Ⅲ) determination were smaller than 5%. The absorbance for As(Ⅴ) could be calculated by subtracting that for As(Ⅲ) measured at 0.4 A from the total absorbance for As(Ⅲ) and As(Ⅴ) measured at 1.2 A, and then the concentration of As(Ⅴ) can be obtained by its calibration curve at 1.2 A. The methodology developed provided the detection limits of 0.3 and 0.6 ng·mL^-1 for As(Ⅲ) and As(Ⅴ), respectively. The relative standard deviations were of 3.5% for 20 ng·mL^-1 As(Ⅲ) and 3.2% for 20 ng·mL^-1 As(Ⅴ). The method was successfully applied to determination of soluble inorganic arsenic species in Chinese medicine.  相似文献   

2.
Mercury as a heavy metal of high toxicity is one of the most harmful elements to human beings and other creatures. Since mercury concentration in natural water is low, proper preconcentration techniques are required to increase its concentration, lower it…  相似文献   

3.
IntroductionIn environment, copper is usually found in traceor ultratrace levels, and its detection requires sensitiveinstrumental measuring techniques such as electrother-mal atomic absorption spectrometry(ETAAS) and ICP-AES or ICP-MS. Frequently, a prec…  相似文献   

4.
In this study, interelement interferences were evaluated for the determination of arsenic in aqueous samples through laser-induced breakdown spectroscopy (LIBS) hyphenated with a hydride generation sample introduction system. Optimum instrumental and chemical parameters were selected and variation in LIBS signal intensity was recorded for As solution in the presence of comparable concentrations of interfering elements. No significant change in the signal intensity of As(I) 228.8?nm line was observed in the presence of alkali/alkali earth metals; however, the presence of hydride-forming elements has shown a noticeable decrease in the line emission strength of arsenic. The least variation in arsenic signal was observed in the presence of Ge, the most volatile of all. However, the signal has decreased to a greater extent in the presence of Sn, Sb, and Pb. The presence of interfering elements on electron temperature and electron number density of arsenic plasma has also been studied. Plasma temperatures calculated using both As and Ar emission lines in the Boltzmann equation were similar, being around 5000?K. The McWhirter criterion for stationary and homogenous plasmas was utilized for the establishment of the local thermodynamic equilibrium under the plasma conditions studied. Applicability of the technique for multielemental analysis of water samples was tested through spiking experiments. Arsenic signal showed 26% decrease in the multielemental mixture solution. LIBS is among a few atomic spectroscopic techniques that facilitate rapid and simultaneous multielemental analysis without extensive sample preparation steps. However, the analytical performance of the technique still requires more serious efforts to compete with other conventional techniques for routine analysis of environmental samples.  相似文献   

5.
《Analytical letters》2012,45(12):1941-1953
The methodology for antimony speciation was optimized for liquid chromatography coupled to hydride generation – atomic fluorescence spectrometry. An anion exchange column was employed with isocratic elution. Ammonium tartrate was shown to be the optimum mobile phase and extracting solution for this analysis. The highest efficiency and resolution for the antimony species was achieved using 5 percent methanol in 300 millimoles per liter ammonium tartrate acidified with hydrochloric acid to pH 4.5. The retention times of antimony(V), trimethylantimony, and antimony(III) were 2.6, 3.9, and 5.2 minutes, respectively. The calibration curves were linear with limits of detection of 0.1, 0.2, and 0.43 microgram per liter for antimony(III), antimony(V), and trimethylantimony, respectively. The precision, evaluated by the relative standard deviation, ranged from 1.2 to 5.3 percent. The average recovery from these environmental samples by a single-step procedure was approximately 26 percent. The results also revealed that the correlation between the sum of each species by the single-step procedure and total digestion was significant for the investigated soils and sediments.  相似文献   

6.
《Analytical letters》2012,45(11):1921-1930
This paper describes a simple and sensitive method for the determination of manganese in human urine by graphite furnace atomic absorption spectroscopy (GFAAS), which includes sample preparation by microwave digestion. Matrix modifier combinations, the digestion power, pyrolysis, and atomization temperatures were optimized. A mixture of 5.0 µg Pd(NO3)2 and 3.2 µg Mg(NO3)2 modifier presented the best performance. The optimal temperatures for pyrolysis and atomization were 1500°C and 1950°C, respectively. The GFAAS method was compared to inductively coupled plasma–mass spectrometry (ICP–MS) for the determination of manganese in urine. Analytical figures of merit for GFAAS and ICP–MS were: accuracy (3.46%, 2.19%), precision (3.61%, 5.84%), LOD (0.109 µg · L?1, 0.015 µg · L?1), LOQ (0.327 µg · L?1, 0.045 µg · L?1), and recovery (80–100%, 74–89%). Both methods were employed for the determination of Mn in urine and the results were compared statistically.  相似文献   

7.
ALI Moghimi 《中国化学》2007,25(5):640-644
A fast and simple method for preconcentration of Ni^2+, Cd^2+, Pb^2+, Zn^2+, Cu^2+ and Co^2+ from natural water samples was developed. The metal ions were complexed with sodium diethyldithiocarbamate (Na-DDTC), then adsorbed onto octadecyl silica membrane disk, recovered and determined by FAAS. Extraction efficiency, influence of sample volume and eluent flow rates, effects of pH, amount of Na-DDTC, nature and amount of eluent for elution of metal ions from membrane disk, break through volume and limit of detection have been evaluated. The effect of foreign ions on the percent recovery of heavy metal ions has also been studied. The limit of detection of the proposed method for Ni^2+, Cd^2+, Pb^2+, Zn^2+, Cu^2+ and Co^2+was found to be 2.03, 0.47, 3.13, 0.44, 1.24 and 2.05 ng·mL^-1, respectively. The proposed (DDTC) method has been successfully applied to the recovery and determination of heavy metal ions in different water samples.  相似文献   

8.
《Analytical letters》2012,45(14):2772-2782
Abstract

A simple and sensitive flow injection on line separation and preconcentration system coupled to hydride generation atomic fluorescence spectrometry (HG‐AFS) was developed for ultra‐trace bismuth determination in water and urine samples. The preconcentration of bismuth on a nylon fiber‐packed microcolumn was carried out based on the retention of bismuth complex with Bismuthiol I. A 15% (v/v) HCl was introduced to elute the retained analyte complex and merge with KBH4 solution for HG‐AFS detection. Under the optimal experimental conditions, an enhancement factor of 20 was obtained at a sample frequency of 24/h with a sample consumption of 13.0 ml. The limit of detection was 2.8 ng/l and the precision (RSD) for 11 replicate measurements of 0.1 µg/l Bi was 4.4%.  相似文献   

9.
《Analytical letters》2012,45(14):2214-2231
Abstract

A new simple and sensitive method has been proposed for rapid determination of trace levels of silver in environmental water samples, using dispersive liquid–liquid microextraction (DLLME) prior to its microsample introduction-flame atomic absorption spectrometry. Under the optimum conditions, the linear range was 0.1–7 µg L?1 and limit of detection was 0.018 µg L?1. The relative standard deviation for 0.50 and 5.00 µg L?1 of silver in water sample was 4.0 and 1.7%, respectively. The relative recoveries of silver from tap, well, river, and seawater samples at spiking levels of 1.00 and 5.00 µg L?1 were in the range of 86.4–98.6%.  相似文献   

10.
《Analytical letters》2012,45(10):1573-1586
Arsenic (As) speciation in edible seaweed has received a considerable research interest due to its impact on the food safety and human health. In this paper, we developed a simple and cost-effective methodology to extract, separate, and analyze As species in Porphyra samples collected from Jiangsu, Zhejiang, and Shandong provinces of China. Four extraction methods were compared in terms of extraction efficiency and resolution of As species. Microwave-assisted water extraction was chosen due to its short time (5 min) and high efficiency (93% of total As extracted). Total As concentration in the Porphyra samples varied within 14.0–42.1 µg g?1, determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES) after acid digestion. Five As species were determined by high performance liquid chromatography—ultraviolet photo-oxidation—hydride generation—atomic fluorescence spectrometry (HPLC–(UV)–HG–AFS). DMA was found only in one sample with the concentration of 0.67 µg g?1. No As(III), As(V), MMA, and AsB were detected. Taken together, the As speciation results suggest that the risk associated with As in Porphyra to human health may be negligible.  相似文献   

11.
《Analytical letters》2012,45(16):2563-2571
Dispersive liquid–liquid microextraction (DLLME) technique combined with electrothermal atomic absorption spectrometry (ET-AAS) was proposed for determination of antimony(III) and total antimony at very low concentrations in water samples. The N-benzoyl-N-phenylhydroxylamine (BPHA) was used as a chelating agent, and chloroform and ethanol were used as extraction and disperser solvents, respectively. The effect of various experimental parameters on the extraction and determination was investigated. The detection limits (3σ) were 0.005 μg L?1 for Sb(III) and 0.008 μg L?1 for total Sb. The developed method was applied successfully to the determination of Sb(III) and total Sb in natural water samples.  相似文献   

12.
lntroductionIngenera1,microwaveplasmaatomicemissionspectrometry(MWP-AES)isanexcel1enttechniqueforthedeterminationofnonmetalelements.AlthoughtheMWP-AEShasbeenextensivelyappliedtothedeterminationofnonmetals,suchasS,P,Cl,BrandI[1],therehavebeenonlyafewreportsonthedeterminationforcarbon.Mitchelletal.[2Jreportedafurnace-microwaveplasmasystemtode-termineorganicandinorganiccarbon.Samplesweredispensedintoplatinumboatsandinsertedintoafurnace.TheresultantvaporwasfedtoanArMWPandcarbonemissionatl…  相似文献   

13.
Abstract

Three extraction methods, acidic KBr/CuSO4 isolation-methylene chloride extraction. acidic KBr/CuSo4 isolation-methylene chloride extraction with an alkaline digestion pretreatment, and an extration method at a milder condition with citrate buffer and dithizone in chloroform, were studied for methylmercury and ethylmercury determination in soils, sediments and fish samples by the recently developed capillary gas chromatography—atomic fluorescence spectrometry system (GC-AFS). The acidic KBr/CuSO4-methylene chloride extraction and the acidic KBr/CuSO4-methylene chloride extraction with an alkaline digestion pretreatment were shown to be the effective methods for soils/sediments and fish samples analysis, respectively. The presence of ethylmercury species in soils of the Florida Everglades, observed with the acidic KBr/CuSO4 isolation and methylene chloride extraction procedure, was further confirmed with the dithizone complexation/extraction procedure. The GC-AFS analytical method offers high senstivity and selectivity for the determination of organomercury halides. The GC column maintenance, a critical step for organomercury halides analysis using GC, is also discussed.  相似文献   

14.
《Analytical letters》2012,45(13):2195-2208
A sensitive and simple method for the determination of trace nickel was developed by the combination of dispersive liquid–liquid microextraction (DLLME) and microsample injection system–flame atomic absorption spectrometry (MIS–FAAS). Trace nickel was preconcentrated as the 8-hydroxyquinoline chelate by DLLME, and the conditions were optimized by a Plackett-Burman design. Quantitative recovery of nickel (98 ± 1%) was obtained by a sample volume of 7.5 mL at a pH of 6.0. The enrichment factor was 52.5, and the limits of detection and quantitation were 0.1 µ g L?1 and 3.0 µ g L?1, respectively. The method was validated by the analysis of a wastewater standard reference material, water samples, and a wire sample. The reported method has superior analytical figures of merit compared with similar methods reported in the literature.  相似文献   

15.
《Analytical letters》2012,45(15):2601-2612
Arsenic speciation in paddy rice is of considerable interest due to its impact on the food safety and human health. In this study, a simple methodology was developed to simultaneously extract and analyze As species in rice from China. Arsenic species, including arsenite (As(III)), arsenate (As(V)), dimethylarsinic acid (DMA), and monomethylarsonic acid (MMA), were extracted by methanol-water (50:50, v/v) containing 0.02 mol L?1 nitric acid with a microwave-assisted procedure, and then determined by high performance liquid chromatography–hydride generation-atomic fluorescence spectrometry (HPLC–HG-AFS). The results showed that the method has good efficiency (>90%) for rice, indicating that there were no significant losses or transformations of arsenic during sample treatment and analysis. The limits of quantification (LOQ) of the method were 8.0, 20, 12, and 12 ng g?1 for As(III), As(V), DMA, and MMA, respectively. When this method was applied to the analysis of rice, As(III) had the highest concentration, followed by DMA, As(V), and MMA. The estimated weekly intake of inorganic As from rice by Chinese people accounted for 11.83% of the provisional tolerable weekly intake. The As speciation results in this study suggest that the risk associated with As in rice to human health may be negligible.  相似文献   

16.
A new method based on the cloud point extraction(CPE) for separation and preconcentration of nickel(Ⅱ) and its subsequent determination by graphite furnace atomic absorption spectrometry(GFAAS) was proposed, 8-hydroxyquinoline and Triton X-100 were used as the ligand and surfactant respectively. Nickel(Ⅱ) can form a hy-drophobic complex with 8-hydroxyquinoline, the complex can be extracted into the small volume surfactant rich phase at the cloud point temperature(CPT) for GFAAS determination. The factors af...  相似文献   

17.
A new method for determining the kinetic order and activation energy for atom formation in electrothermal atomic absorption spec-trometry is proposed. The assumption of first order kinetics for atom formation and the steady-state approximation which appeared in the previous models is avoided in the proposed method. The kinetic parameters for atom formation of Li have been obtained, and the effect of the amount of analysed sample, ashing temperature, atomization temperature, heating rate, gas flow and tube surface on the atomization of Li has also been investigated.  相似文献   

18.
Orthogonal array design was used to optimize arsenic speciation in drinking water in contact with materials by dispersive liquid–liquid microextraction followed by graphite furnace atomic absorption spectrometry. Arsenic speciation was achieved by the formation of an arsenic(III) hydrophobic complex with a new chelating agent, 1,2,6-hexanetriol trithioglycolate, at neutral pH. The complex was extracted into the organic phase, while arsenic(V) remained in aqueous solution. The concentration of As(V) was determined by subtracting As(III) from the total arsenic following the reduction of As(V) to As(III) by L-cysteine. Orthogonal array design with OA16 (44) and OA9 (33) matrices was used to optimize the efficiency of dispersive liquid–liquid microextraction and the reduction of As(V) to As(III), respectively. Under the optimal conditions, the detection limit was 0.03?µg?L?1 for As(III) and the relative standard deviation was 5.9% with an enhancement factor of 87. The calibration curve was linear from 0.19 to 3.0?µg?L?1 with a correlation coefficient of 0.9996. The developed method was used for arsenic speciation in solutions of drinking water that contacted materials. The recoveries of fortified samples were in an acceptable range from 92.0 to 113.3%.  相似文献   

19.
A simple and reliable method for the extraction and determination of trace amounts of copper(Ⅱ) ions using activated carbon (AC) impregnated by a new Schiff base 5-[(4-heptyloxyphenyl)azo]-N-(4-propyloxyphenyl)-salicylaldimine (HPPS) and atomic absorption spectrometry is presented. Recovery efficiency and the influence of pH value, volume of sample solution, effect of different eluents, and interfering ions were evaluated. The limit of detection (3σ) was 2.62 ng.mL^-1 and the relative standard deviation (n=10) was 1.5%. Under optimum conditions, the copper ions were concentrated 25 fold using 250 mL of sample solution and 10 mL of eluent. This procedure has been successfully applied to the determination of copper in different water samples.  相似文献   

20.
Fish are an important human food with increasing consumption in recent decades. Diet is the main route of exposure to heavy metals for human health. For this reason, many studies have been performed on the pollution by heavy metals in different species of fish. Our main objective was to evaluate the pollution by trace metals (Zn, Cu, Pb, and Cd) in sardine muscles collected from the bay of Boumerdés (Algeria). Flame atomic absorption spectroscopy (AAS) was used for the quantification of Cu and Zn. The quantification of Cd and Pb was achieved by graphite furnace (GF) AAS. The analysis revealed the presence of metal trace elements in the muscles of species at concentrations below the thresholds established by national and international regulations.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号