化学蒸气发生-四通道原子荧光光谱法同时测定水样中的痕量砷、锑、硒和汞

应用自行设计的化学蒸气发生-四通道无色散原子荧光光谱仪,建立了同时测定水样中As、Sb、Se、Hg的新方法.在实验中优化了四元素同时化学蒸气发生条件和测定的最佳工作参数.在样品预处理阶段用HCl将Se6+还原为Se4+,然后用质量浓度5 g/L硫脲将As5+和Sb5+还原为As3+和Sb3+.在最佳条件下,方法对As、Sb、Se、Hg的检出限分别为0.05、0.03、0.05、0.01 ng/mL(3d);RSD分别为0.42%、0.74%、0.97%、1.0%(对5 ng/mL As、Sb、Se和0.5ng/mL Hg混合标准,n=7).用所建立的方法对不同类型水样中的As、Sb、Se、Hg进行了同时测定,测定结果与用标准方法测定所得结果之间无明显差异,各元素的加标回收率在93%～105%.     

Simultaneous determination of arsenic, selenium, tin and mercury by non-dispersive atomic fluorescence spectrometry

A procedure is described for simultaneous determination of arsenic, selenium, tin and mercury in aqueous solution by non-dispersive atomic-fluorescence spectrometry. Radiofrequency-excited EDLs, 100% modulated in the kHz region, were used for atom excitation. Sodium tetrahydroborate was used as reductant and a hydrogen-argon miniflame as atomizer. In the optimized procedure, which uses 1 ml of sample, the limits of detection (three times the standard deviation of the blank) were 0.04, 0.08, 0.1 and 0.1 ng ml for arsenic, selenium, tin and mercury respectively. The linear dynamic range was greater than three decades for all analytes and the precision was better than 7% (typically 3%) for concentrations 1 ng ml . Results for mutual interference effects are reported. Copper, nickel, lead and cobalt interfered only with selenium (5 ng ml ), when present in at least 200-fold weight ratio to it. Using 5 ml of sample improved the limits of detection for selenium and arsenic (0.01 and 0.02 ng ml respectively), but at the expense of greater interference. Recovery from spiked natural water samples was better than 95% at the ng ml level, except for selenium in sea-water, when the recovery was only 85%. Determination of the four elements, including standard-addition and background measurements, requires about 10 min.     

氢化物发生-原子荧光光谱法同时测定中药材中砷和汞

采用氢化物发生-原子荧光光谱法同时测定了产于吉林省长白山的中药材杜仲中砷和汞的含量,建立了同时测定砷汞含量的分析方法。讨论了各种对测定有影响的因素,并优化了分析条件。方法的检出限分别为2.9×10-4μg/mL(砷),0.013ng/mL(汞)。该方法简便、快速且灵敏度高,样品测定结果满意。     

Determination of Selenium in Foodstuffs by Cathodic Stripping Voltammetry at a Mercury–Graphite Electrode

A universal procedure was developed for the voltammetric determination of total selenium in various foodstuffs. The procedure involves the mineralization of a test sample with magnesium nitrate followed by the reduction of selenium(VI) to selenium(IV) in 6 M HCl and the determination of selenium by cathodic square-wave voltammetry at a mercury–graphite electrode in an HCl solution in the presence of copper and mercury ions.     

Simultaneous determination of arsenic,mercury, antimony and selenium in biological materials with prior collection of gaseous products followed by neutron activation analysis

A method combining prior collection of gaseous products with subsequent neutron activation analysis has been developed for simultaneous determination of traces of arsenic, mercury, antimony and selenium in biological materials. The generation of hydrides of arsenic, antimony and selenium and cold vapor of mercury in the vapor generaion and collection system was investigated by the use of radiotracers of the respective elements. The result indicates that selenium and mercury can be completely evaporated from the digested sample solution in 5M HCl with the addition of 5% sodium tetrahydroborate solution, while additional reduction proces by potassium iodide and ascorbic acid is needed for complete evaporation of arsenic and antimony. The gaseous products were collected in a quartz tube for neutron irradiation. The detection limits of these elements were fount to be in the range of 10^–7 to 10^–8 g under the present experimental conditions. The reliability was checked with NBS standard reference materials.     

Difficulties with the Determination of Mercury in Foodstuffs by Stripping Voltammetry

The main problems with the determination of mercury in foodstuffs by stripping voltammetry were analyzed. The conditions for obtaining the analytical signal from mercury(II) at a gold–graphite electrode and for reducing the effect of interfering substances were refined. A simplified procedure for the preparation of foodstuff samples by the chemical (HNO₃ + H₂O₂) and photochemical oxidation of samples was proposed. The determination conditions were optimized by the fractional factorial design of the experiments. It was shown that a gas-discharge XeBr excilamp can be used as an alternative to a mercury quartz lamp in the sample preparation of foodstuffs. The conditions for reducing the blank experiment and its contribution to the results of determination were considered.     

水为载流-原子荧光光谱法同时测定土壤中痕量砷、汞

改变原子荧光光谱法以稀酸为载流的进样方式,以水为载流在新型双道原子荧光光谱仪上同时测定了土壤中的痕量砷(As)、汞(Hg)。方法采用王水水浴加热溶解样品,用50 g/L硫脲-抗坏血酸混合溶液预先将砷还原为+3价,保持10%(体积分数)以上盐酸浓度,不转移直接定容静置后测定。优化了仪器工作条件,详细考察了以水为载流测定的可行性,选择了同时测定As、Hg所需的硼氢化钾浓度和盐酸浓度。方法节省了酸试剂用量,操作快速,单个样品测定仅需20s左右。方法检出限As为0.005 mg/kg,Hg为0.0008 mg/kg,相对标准偏差(RSD%,n=7)在1.0%～7.4%,经土壤国家标准物质和实际样品验证,适合土壤中痕量As、Hg的同时快速测定。     

水载流-原子荧光光谱法同时测定土壤中痕量砷、汞

改变原子荧光光谱法以稀酸为载流的进样方式,以水为载流在新型双道原子荧光光谱仪上同时测定了土壤中的痕量砷(As)、汞(Hg).采用王水水浴加热溶解样品,用50 g/L硫脲-抗坏血酸混合溶液预先将砷还原为As(Ⅲ),保持10％(体积分数)以上盐酸浓度,不转移直接定容静置后测定.优化了仪器工作条件,详细考察了以水为载流测定的...     

The Simultaneous Arsenic,Antimony, and Selenium Determination in Water Samples by Batch Hydride Generation Atomic Absorption Spectrometry

The purpose of this paper is to present a procedure for the simultaneous determination of metalloids: arsenic, antimony, and selenium. Hydride generation was provided in a reaction vessel connected with the atomic absorption spectrometer (AAS) in a fast sequential mode. Two different types of water samples were used while developing the application: seawater and groundwater. The methodology of liquid samples analysis was developed with detection limits of 0.05, 0.03, and 0.06 ng · mL^?1 for arsenic, antimony, and selenium, respectively, in 10 mL samples. This methodology was used to determine arsenic, antimony, and selenium in natural water samples.     

Method for Determination of Selenium and Arsenic in Human Urine by Atomic Fluorescence Spectrometry

Abstract

The study presents the method for simultaneous determination of selenium and arsenic in human urine by atomic fluorescence spectrometry (AFS). According to the procedure developed, a sample is first digested in the microwave system, then chemically treated in the flow through a hydride generation system, and finally exposed to measurements in a double‐channel atomic fluorescence spectrometer. It has been revealed that selenium and arsenic can be accurately determined with detection limit of 0.13 and 0.16 µg/L and repeatability (RSD) of 1.0 and 1.2%, respectively. The urine samples taken from a control group and from persons subjected to a special diet were analyzed. The obtained results proved that the method developed was capable of controlling reliably even slight changes of both elements in a wide range of their concentrations, and, as such, that it can be recommended to be used for clinical and toxicological purposes.     

Determination of arsenic, antimony and selenium in biological samples by hydride evolution and X-ray fluorescence spectrometry

Summary A method for the simultaneous determination of arsenic, selenium and antimony in biological samples by means of wavelength dispersive X-ray fluorescence spectrometry (XRFS) is described. The method entails a procedure for the destruction of the biological material, followed by the simultaneous generation and accumulation of the hydrides of the elements of interest onto an impregnated cellulose filter, and measurement by XRFS.     

Simultaneous determination of arsenic, antimony, bismuth and mercury in geological materials by vapor generation-four-channel non-dispersive atomic fluorescence spectrometry

Chemical vapor generation (CVG) coupled with non-dispersive atomic fluorescence spectrometry (NDAFS) has been widely used for determination of vapor-forming elements, but most of such works have been focused on single element analysis, and reports dealing with more than three elements simultaneous determination by CVG-NDAFS are rare. In this work, a sensitive and robust analytical procedure for the simultaneous determination of arsenic, antimony, bismuth and mercury in geological materials using vapor generation-four-channel non-dispersive atomic fluorescence spectrometry has been developed. The conditions of instrumentation and vapor generation of arsenic, antimony, bismuth and mercury were optimized. The optimized concentrations of KBH(4) and HCl required for analytes generation were 1.3% (m/v) and 20% (v/v), respectively. The interferences of coexisting ions and mutual hydride interferences were investigated carefully. One thousand milligrams per litre of Fe(3+); 500mgl(-1) of Pb(2+), Zn(2+), Mn(2+); 50mgl(-1) Cu(2+), Ni(2+), Cr(6+), Co(2+); 10mgl(-1) Ag(+) and 5mgl(-1) Au(3+) does not interfere with the determination of As, Sb, Bi and Hg. Associating a dilution of 1:250 (m/v) in the procedure of sample pretreatment, the tolerant concentrations of As, Sb, Bi and Hg in real geological materials are 2500, 1000, 250 and 5000ppm, respectively. Under optimal conditions, the detection limits for As, Sb, Bi and Hg were determined to be 0.068, 0.047, 0.037 and 0.008ngml(-1), respectively. The precisions for seven replicate determinations at the 5ngml(-1) of As, Sb, Bi and 1ngml(-1) of Hg were 0.47, 0.60, 0.97 and 0.93% (R.S.D.), respectively. Sample digestion was carried out on 500mg sample with 3ml HNO(3) and 10ml HCl, followed by addition of thiourea solution for the quantitative reduction of As(V), Sb(V) to As(III), Sb(III). The proposed method was successfully applied to the simultaneous determination of As, Sb, Bi and Hg in a series of certified geological reference materials using simple aqueous standard calibration technique. The results obtained are in good agreement with the certified values.     

一次消解土壤样品测定汞、砷和硒

建立了测定土壤中3种挥发性元素(汞、砷、硒)的一次消解方法,确定以程序控温石墨自动消解仪+王水-氢氟酸-硼酸络合敞开体系为最佳消解体系,采用氢化物发生-原子荧光光谱法(HG-AFS)分别测定同一消解液中汞、砷、硒的含量.采用国家标物中心有证标准物质土壤环境样品GSS-1~GSS-8进行了方法验证,结果均符合标准偏差的允许范围.此消解方法相比于现行标准方法,避免了针对各元素的分次处理,简化了消解步骤,节省了前处理时间,减少了试剂消耗,提高了实验效率,适用性广、灵敏度高、检出限低,尤其适合批量样品的微量/痕量元素分析,可作为一种大规模土壤样品中重金属污染监测和治理的快捷方法.     

Application of multivariate techniques in the optimization of a procedure for the determination of bioavailable concentrations of Se and As in estuarine sediments by ICP OES using a concomitant metals analyzer as a hydride generator

A procedure has been developed for the determination of bioavailable concentrations of selenium and arsenic in estuarine sediments employing inductively coupled plasma optical emission spectrometry (ICP OES) using a concomitant metals analyzer device to perform hydride generation. The optimization of hydride generation was done in two steps: using a two-level factorial design for preliminary evaluation of studied factors and a Doehlert design to assess the optimal experimental conditions for analysis. Interferences of transition metallic ions (Cd²⁺, Co²⁺, Cu²⁺, Fe³⁺ and Ni²⁺) to selenium and arsenic signals were minimized by using higher hydrochloric acid concentrations. In this way, the procedure allowed the determination of selenium and arsenic in sediments with a detection limit of 25 and 30 μg kg⁻¹, respectively, assuming a 50-fold sample dilution (0.5 g sample extraction to 25 mL sample final volume). The precision, expressed as a relative standard deviation (% RSD, n = 10), was 0.2% for both selenium and arsenic in 200 μg L⁻¹ solutions, which corresponds to 10 μg g⁻¹ in sediment samples after acid extraction. Applying the proposed procedure, a linear range of 0.08-10 and 0.10-10 μg g⁻¹ was obtained for selenium and arsenic, respectively. The developed procedure was validated by the analysis of two certified reference materials: industrial sludge (NIST 2782) and river sediment (NIST 8704). The results were in agreement with the certified values. The developed procedure was applied to evaluate the bioavailability of both elements in four sediment certified reference materials, in which there are not certified values for bioavailable fractions, and also in estuarine sediment samples collected in several sites of Guanabara Bay, an impacted environment in Rio de Janeiro, Brazil.     

HG/LT-GC/ICP-MS coupling for identification of metal(loid) species in human urine after fish consumption

Human urine samples after fish consumption have been investigated by low-temperature gas chromatography with inductively coupled plasma mass spectrometric detection after sample derivatization by hydride generation (HG/LT-GC/ICP-MS). This analytical technique enabled the identification of organometal(loid) compounds in human urine; species of the six elements germanium, arsenic, selenium, tin, antimony, and mercury were determined. Three different organic selenium species, two germanium species, seven arsenic species, four tin species, five antimony species, and one species of mercury were found; 18 of the 22 species detected could be identified. The relative detection limits ranged between 2 and 12 pg x L(-1) (x=element). These organometal(loid) compounds probably build up in the human body under the influence of micro-organisms, in the presence of hydrogen sulfide and methane, in the human intestine.     

Simple and sensitive determination of arsenic by volatile arsenic trichloride generation atomic fluorescence spectrometry

A simple, sensitive and interference-free method was proposed for the determination of arsenic, based on the generation of volatile arsenic trichloride coupled with atomic fluorescence spectrometry. Thiourea, together with l-ascorbic acid, was used to reduce As(V) to As(III), and the chloride generation was based on the reaction between As(III) and hydrochloric acid. Under the optimized experimental conditions, the present procedure allows for the quantification of arsenic in the concentration range of 0.01–4.0 mg L⁻¹, with a limit of detection (3σ) of 6.0 μg L⁻¹. The relative standard deviation (R.S.D.) is 4.0% for 0.1 mg L⁻¹ arsenic (n = 7). Finally, the proposed method was successfully applied to the determination of arsenic in several certified reference samples (stainless steel, alloy steel, copper alloy and water sample) and real samples (brass material and spiked cobalt material), with analytical results well-agreed with those by ICP-MS.     

Determination of arsenic and selenium by hydride generation and headspace solid phase microextraction coupled with optical emission spectrometry

A hydride generation headspace solid phase microextraction technique has been developed in combination with optical emission spectrometry for determination of total arsenic and selenium. Hydrides were generated in a 10 mL volume septum-sealed vial and subsequently collected onto a polydimethylsiloxane/Carboxen solid phase microextraction fiber from the headspace of sample solution. After completion of the sorption, the fiber was transferred into a thermal desorption unit and the analytes were vaporized and directly introduced into argon inductively coupled plasma or helium microwave induced plasma radiation source. Experimental conditions of hydride formation reaction as well as sorption and desorption of analytes have been optimized showing the significant effect of the type of the solid phase microextraction fiber coating, the sorption time and hydrochloric acid concentration of the sample solution on analytical characteristics of the method developed. The limits of detection of arsenic and selenium were 0.1 and 0.8 ng mL^− 1, respectively. The limit of detection of selenium could be improved further using biosorption with baker's yeast Saccharomyces cerevisiae for analyte preconcentration. The technique was applied for the determination of total As and Se in real samples.     

Simultaneous determination of arsenic, antimony, selenium and tin by gas phase molecular absorption spectrometry after two step hydride generation and preconcentration in a cold trap system

A cold trap system for the simultaneous determination of arsenic, antimony, selenium and tin by continuous hydride generation and gas phase molecular absorption spectrometry is described. The hydride generation is carried out in two steps; first, tin hydride is generated at low acidity and second, arsenic, antimony and selenium hydrides are formed at higher acidity. All the hydrides are collected in a liquid nitrogen cryogenic trap and transported to the flow cell of a diode array spectrophotometer, where molecular absorption spectra are obtained in the 190-250 nm range. Five calibration solutions containing arsenic, antimony, selenium and tin are solved using multiple linear regression analysis. Tests are performed in order to extend the same manifold to other hydrides but no signals are obtained for bismuth, cadmium, lead, tellurium and germanium. Under the optimum conditions found and using the wavelengths of maximum sensitivity (190, 198, 220 and 194 nm), the analytical characteristics of each element are calculated. The detection limits are 0.050, 0.020, 0.12 and 1.1 mug ml(-1) and the RSD values are 3.7, 3.1, 3.5 and 3.0% for As, Sb, Se and Sn, respectively. The method is applied to As, Sb, Se and Sn determination in natural spiked water samples.     

Routine determination of mercury,arsenic and selenium by radiochemical Neutron Activation Analysis

A method for the determination of mercury, arsenic and selenium by neutron activation analysis is described. Radiochemical separations are performed by selective distillation followed by electrolysis of mercury on gold and precipitation of arsenic and/or selenium by reduction to the elemental form. The chemical yields are 80–90% for mercury and 90–100% for arsenic and selenium. Interference tests have been carried out with reference to those elements most likely to interfere with the analysis. Detection limits for mercury, arsenic and selenium using 0.1 g of sample are 0.2 ng g^–1, 2 ng g^–1 and 3 ng g^–1, resp. Detection limits can be improved using greater sample size and neutron flux density. Results from the analysis of several NBS standard reference materials are given.     

微波消解–原子荧光光谱法测定植物样品中的砷和硒

建立微波消解-原子荧光光谱法测定植物样品中砷和硒的含量。微波消解后残留的有机颗粒和硝酸等会对测定结果造成影响,因此需要将硝酸除尽。在驱除硝酸过程中加入高氯酸,加热至溶液冒白烟,避免硒挥发损失。该方法砷、硒的检出限分别为6.8,4.0 ng/g(稀释因子40),测定结果的相对标准偏差分别为3.65%,3.52%(n=12),加标回收率分别为94.5%~104.6%,92.2%~98.9%。经过国家一级标准物质验证,该方法准确可靠。