Determination of heavy metal ions by microchip capillary electrophoresis coupled with contactless conductivity detection

An integrated detection circuitry based on a lock-in amplifier was designed for contactless conductivity determination of heavy metals. Combined with a simple-structure electrophoresis microchip, the detection system is successfully utilized for the separation and determination of various heavy metals. The influences of the running buffer and detection conditions on the response of the detector have been investigated. Six millimole 2-morpholinoethanesulfonic acid + histidine were selected as buffer for its stable baseline and high sensitivity. The best signals were recorded with a frequency of 38 kHz and 20 V(pp). The results showed that Mn(2+), Cd(2+), Co(2+), and Cu(2+) can be successfully separated and detected within 100 s by our system. The detection limits for five heavy metals (Mn(2+), Pb(2+), Cd(2+), Co(2+), and Cu(2+)) were determined to range from about 0.7 to 5.4 μM. This microchip system performs a crucial step toward the realization of a simple, inexpensive, and portable analytical device for metal analysis.     

Determination of trace metallic impurities in high-purity quartz by ion chromatography

A method has been developed for the determination of relevant trace impurities (alkali, alkaline and transition metals) in high purity quartz by ion-chromatography. In situ reagent (HF) purification and simultaneous sample dissolution was achieved in a multichannel vapour phase digestion assembly. Twenty-one samples can be digested at a time in this vapour phase system. Significant decrease in the process blank levels for all the analytes was observed. Drastic reduction (250 times) of NH4+ blank was achieved in the described vapour phase digestion, which enables the determination of trace concentration of sodium in high purity quartz. After volatilisation of the matrix and unreacted HF, the clear water leached solutions were injected into an ion-chromatograph equipped with conductivity detector for the determination of alkali and alkaline earth metals. In the case of transition metals, the trace residues were leached with 10 mM HCl and after separation on a mixed bed analytical column (IonPac CS5) were detected by spectrophotometry after post column derivatisation using 4-(2-pyridylazo)resorcinol (PAR). The accuracy of the result was checked by their comparison with those obtained by independent methods like inductively coupled plasma (ICP) MS and ICP atomic emission spectrometry. The achievable detection limits are between 0.4 ng/g (Li) and 22 ng/g (Mn). The application of the method to the determination of the above trace metals in two high-purity-grade quartz samples is demonstrated.     

流动注射-原子吸收分光光度法测定彩电荧光屏壁玻璃中钾钠钙镁铁

本文应用流动注射分析-原子吸收分光光度法(FLA-AAS)测定彩电荧光屏壁玻璃中的钾、钠、钙、镁、铁的含量、对方法中可能存在的各种影响因素、干扰情况及其消除等进行了较为详细的研究.应用所建立的方法对样品测定取得了满意结果.本文对所建立的FIA-AAS法与常规AAS法进行了比较及讨论     

Determination of trace heavy metals in waters by atomic-absorption spectrometry after preconcentration by liquid-phase polymer-based retention

A new method for the determination of metals in waters by flame atomic-absorption spectrometry is described. The metals are retained by water-soluble polymers in a membrane filtration cell and the factors which influence their determination are discussed. The method has been applied to the determination of Ni, Cu, Zn, Hg and Cd in drinking and river water with poly(ethyleneimine) and its thiourea derivative as complexing polymers. The metals were determined in the aqueous concentrate after a 250-fold preconcentration by 2% polymer solution at pH 7. The metal recoveries were at least 92%, and the limits of detection (ng/mg) were 0.012 for Cu, 0.006 for Zn, 0.03 for Ni, 0.004 for Cd and 0.0001 for Hg (cold vapour method). When a new type of membrane filtration cell is used even higher preconcentration factors can be achieved and lower concentrations can be determined.     

Analysis of leachable and total trace metals in air particulate matters by capillary electrophoresis

A new analytical procedure was developed for simultaneous determination of ammonium, leachable and total metals in fine and coarse air particulate matters using a new capillary electrophoresis (CE) procedure, with a new buffer system containing 10 mM histidine, 2 mM 18-crown-6 and 8 mM lactic acids with pH adjusted to 4.0. A two complexes system, 18-crown-6 ether and lactic acid, was developed to solve the co-migration problem of NH(4)(+) and K(+) and to give satisfactory separation of transition metals. Satisfactory separation and quantitation of NH(4)(+), K(+), Ca(2+), Na(+) , Mg(2+) and Zn(2+) were obtained using the CE procedure developed for both leachable and total metals in coarse (10-3 mum) and fine (<3 mum) air particulate matters. Wide working ranges (ppb to ppm range) and sensitive detection limits (ppb) were obtained for the cations investigated. The reliability was established by parallel method comparison with the ICP-AES method. The analytical procedure developed is shown to provide a quick, sensitive, precise and economic method for simultaneous determination of ammonium, leachable and total metals in air particulate matters.     

Determination of metal ions by ion chromatography with precolumn electrochemical preconcentration

The determination of heavy metals in concentrations less than 10(-6) mol/L by ion chromatography with conductivity detection requires a preconcentration step. Therefore, a special electrochemical equipment and method was developed for the on-line preconcentration of the divalent metals Ni, Co, Zn and Cd and their subsequent ion chromatographic determination. The loop of the injection valve of an ion chromatograph was replaced by an electrochemical flow-through-cell with a gold working electrode, a platinum auxiliary electrode and a silver/silver sulphate reference electrode. The preconcentration step consists of the deposition of the reduced metals on the electrode surface during a continuous pumping of the sample solution through the cell. After switching of the mobile phase through the cell, the analytes are injected after their reoxidation directly into the mobile phase. A new preconcentration step is simultaneously possible during the actual chromatographic run. An effective separation of the analytes from the matrix is also possible with the proposed system. A maximum of metal ion accumulation was obtained after 120 min in the galvanostatic mode on a gold tube electrode. The detection limits for Co(II), Ni(II), Zn(II) and Cd(II) were improved by a factor of 7.7, 10.4, 11.2, 14.0, respectively, and were in the 0.1 micromol/L concentration range with a RSD of 2-6%. The accumulation of metal ions was disturbed in the presence of Cr(III).     

The determination of dissolved manganese and cadmium in sea water at low nmol 1−1 concentrations by chelation and extraction followed by electrothermal atomic absorption spectrometry

The development and application of a method suitable for the determination of dissolved manganese and cadmium in sea water at the low concentrations typical of the open ocean is described. A mixed dithiocarbamate/Freon TF extraction system is used to separate trace metals from major constituents, prior to back extraction into a final dilute nitric acid solution and subsequent determination of the metals by graphite-furnace atomic absorption spectrometry. The procedure also separates dissolved Co, Cu, Fe, Ni, Pb and Zn from a sea-water matrix. A mechanized system for the extraction step and measures to control contamination are described. The detection limits (3 σ) for manganese and cadmium are 0.10 and 0.04 nmol l^?1, respectively.     

海水重金属电化学传感器检测系统

研制了一种新型的海水重金属电化学传感器流动分析系统.通过在线过滤、紫外线消解、电化学富集以及离子选择性电极电位测定等过程,实现对海水重金属的高灵敏、高选择性的快速检测.在海水基体条件下,对于镉、铅和铜的测定线性范围分别为1.0×10-9～1.0×10-7 mol/L,3.0×10-9～1.0×10-7 mol/L和1.0×10-9～1.0× 10-7 mol/L,相应检出限为2.8×10-10,6.6×10-10和5.1×10-10 mol/L,连续6次测定的RSD均小于5％,全程分析在25 min内完成.应用于实际海水样品分析,其测定结果与溶出伏安法一致.此传感器性能可靠、成本低廉,在海水重金属现场快速监测方面具有良好的应用前景.     

电感耦合等离子体原子发射光谱法(ICP-OES)与石墨炉原子吸收光谱法测定饮用水中重金属元素的比较

通过对比电感耦合等离子体原子发射光谱法(ICP-OES)与石墨炉原子吸收光谱法(AAS)测定水中重金属的检出限、重复性、加标回收率等实验,验证两种方法的准确性,从而为饮用水中重金属的测定提供可靠的方法。结果表明,石墨炉原子吸收光谱法测定饮用水中砷、镉、铬、铅、汞、硒的检出限均低于ICP-OES法,但ICP-OES法测定线性范围宽,重复性和加标回收率均优于石墨炉原子吸收光谱法,分析速度快,操作便捷,结果满意,是目前饮用水中重金属测定非常可靠的方法。     

Determination of Hg,As, Pb,and Cd in Orchard Soils by Sequential Injection Vapor Generation Atomic Fluorescence Spectrometry

An analytical procedure was developed for determination of Hg, As, Pb, and Cd in soil samples using sequential injection vapor generation atomic fluorescence spectrometry (SI-VG-AFS) with sample preparation by microwave digestion system. The effects of analytical conditions on the fluorescence intensity were investigated and optimized. Under the optimized condition, the detection limits of the method were 5, 68, 40, and 3 ng L^?1 for Hg, As, Pb, and Cd, respectively. The accuracy of method was verified by the determination of the certified reference soil, and the recoveries for Hg, As, Pb, and Cd were in the range of 98.7–106.1%. The proposed method has been successfully applied to determine the heavy metals in navel orange orchard soils in Ganzhou, and the environmental quality of the orchard soils was assessed based on the content of the heavy metals. According to the second criterion of environmental quality standard for soils, Pb content in all soil samples collected from the orchards of 18 districts were within safe limits, but a few orchards were slightly contaminated with Hg, As, and Cd. Comparison of heavy metal mean concentrations with the safe limits of environmental quality standard for soils, the quality of Ganzhou navel orange orchard soils were in line with the request of the green food production base.     

Determination of trace metals in waters and compost by on-line precipitation coupled to flame atomic absorption spectrophotometry or ion chromatography

A general rapid on-line preconcentration method for the determination of trace metals coupled to flame atomic absorption spectrophotometry (FAAS) or ion chromatography (IC) with spectrophotometric detection is described. The method is based on the on-line precipitation of metal hydroxides with sodium hydroxide and their dissolution in a small volume of nitric acid solution. All the chemical and physical variables that affect the efficiency of metal precipitation and elution in the flow injection system have been studied. The detection limits obtained by FAAS are 0.1, 0.3, 0.5 and 0.5 mug l(-1) for Zn, Cu, Ni and Pb, respectively. When the on-line precipitation is coupled to IC with post-column derivatization with the spectrophotometric reagent 4-(2-pyridylazo) resorcinol (PAR), the detection limits are 3, 1, 5, 3, and 3 mug l(-1) for Cu, Zn, Ni, Co and Mn, respectively. The proposed general method was successfully applied to determine independently the above mentioned metals in compost and tap and river water samples.     

Simultaneous determination of copper and lead in ethanol fuel by anodic stripping voltammetry

The presence of trace metals in car fuels plays an important role in the engine maintenance. In addition, these metals contribute for the environmental contamination in big cities and their control is necessary. Square Wave Stripping Voltammetry (SWSV) is a very sensitive technique for elemental trace determination and was applied for ethanol fuel analysis. The first studies were done searching for the best conditions for copper determination in alcoholic medium, utilizing gold electrodes. During these studies, the possibility of the simultaneous determination of copper and lead in the same experiment was observed. Two procedures for the analysis of these metals were adopted: The direct quantification of metals in alcohol–water mixtures and a second way that involves the evaporation of the organic solvent and re-suspension of the ions with water+electrolyte. Good recovery values were obtained for synthetic samples spiked with known amounts of metals. The results obtained for the two methods were in good agreement. The detection limits for copper and lead in 75% ethanol–water ratio solution were calculated as 120 and 235 ng l⁻¹, respectively, for 15-min deposition time.     

Individual catalytic determination of iridium and rhodium using the oxidation of sulfarsazene by potassium periodate as an indicator reaction in a flow-injection system

A catalytic method has been developed for the individual determination of trace iridium and rhodium using the oxidation of sulfarsazene by potassium periodate as an indicator reaction in a flow-injection system. The analytical range is from 0.10 to 2.0 μg/mL iridium and from 0.0010 to 0.027 μg/mL rhodium. The detection limits are 0.0074 μg/mL iridium and 0.00095 μg/mL rhodium; the determination error does not exceed RSD = 4% in model solutions. The method is selective in the presence of the majority of colored and platinum-group metals. The accuracy of the results has been confirmed by the standard addition method.     

Determination of Ni,Co, and Cu in seawater by total external reflection X-ray fluorescence spectrometry

Total external reflection X-ray fluorescence spectrometry is a promising method for the highly sensitive determination of heavy metals in seawater, offering such advantages as the mobility of the used equipment and the low cost of analysis. Various methods of sample preparation to the analysis of seawater aimed at the elimination of interferences with the salt matrix were compared. It was shown that the method based on the preliminary extraction of metals as diehyldithiocarbamate complexes followed by back extraction is characterized by the highest efficiency. A procedure was developed for the determination of Ni, Cu, and Co in seawater with limits of detection at a level of 0.16–0.26 μg/L.     

Determination of trace metals in the River Ye?il?rmak sediments in Tokat, Turkey using sequential extraction procedure

Sequential extraction procedure (acid extractable, reducible, oxidizable, and residual) proposed by BCR was applied for the determination of trace metals in the River Yesilirmak sediments, Tokat, Turkey. The determination of trace metals in sediment samples was performed by flame atomic absorption spectrometry. The proposed method showed satisfactory recovery, detection limits and standard deviation for trace metals determination in sediment samples. Generally, most of the elements were found in the oxidizable and residual fractions. The total concentrations of trace metals analyzed were found to be (mg/kg) Cu: 37.9, Mn: 392.2, Zn: 126.2, Fe: 3726, and Pb: 29.6, respectively. Results obtained are in agreement with data reported in the literature.     

电感耦合等离子体质谱(ICP-MS)法测定谷类产品中8种重金属元素

为建立大批量谷类产品中重金属元素的快速检测方法,采用快速消解法,样品于聚丙烯刻度离心管中经硝酸消解,用电感耦合等离子体质谱仪同时检测Pb、Cd、Cr、Cu、Zn、Ni、As、Hg等8种重金属元素含量.研究了消解酸用量及消解时间对结果的影响,并优化了仪器工作参数.研究结果表明,样品在120℃消解1 h后直接定容测定,各元...     

Determination of heavy metal complexes with humic substances by HPLC/ICP-MS coupling using on-line isotope dilution technique

An isotope dilution mass spectrometric (IDMS) method has been developed for the simultaneous determination of the complexes of 11 heavy metals (Ag, Cd, Cu, Mo, Ni, Pb, Tl, U, W, Zn and Zr) with humic substances (HS) by coupling HPLC with ICP-MS and applying the on-line isotope dilution technique. The HPLC separation was carried out with size exclusion chromatography. This HPLC/ICP-IDMS method was applied to samples from a brown water, ground water, sewage and seepage water as well as for a sample containing isolated fulvic acids. The total contents of heavy metals and of their complexes were analyzed in these samples with detection limits in the range of 5–110 ng/L. The analysis of heavy metal/HS complexes from the different waters resulted in characteristic fingerprints of the distribution pattern of heavy metals in the separated HS fractions. A comparison between the total heavy metal concentrations and their portions bound to humic substances showed distinct differences for the various metals. Simultaneous ¹²C detection was used for the characterization of HS complexes not identified by UV detection and for the determination of relative DOC concentrations of chromatographic peaks. Received: 21 February 1997 / Revised: 27 May 1997 / Accepted: 28 May 1997     

Determination of Copper,Nickel and Cadmium by Faas After Preconcentration with Zinc-Piperazinedithiocarbamate Loaded on Activated Carbon by Solid-Phase Extraction

ABSTRACT

A method was developed for the preconcentration of copper, nickel and cadmium in water samples, prior to their determination by FAAS, using the Zn-piperazinedithiocarbamate complex (ZnPDC) loaded on activated carbon. In this method, Cu, Ni and Cd in liquid phase quantitatively replaced zinc on a ZnPDC-activated carbon solid phase. Afterwards, the metals on the solid phase were easily eluted by Hg (II) solution into aqueous phase, and were measured by FAAS. The optimum experimental parameters such as pH, sample volume, and effect of matrix ions for the preconcentration of the metals were investigated. The range of linearity 0-6, 0-5, 0-3 μgml^?1, correlation coefficient 0.998, 0.996, 0.999, detection limits 15.7, 23.5, 11.8 ngml^?1 and determination limits 136, 179, 98 ngml^?1 in final Hg(II) solution were obtained for Cu, Ni and Cd, respectively. The proposed method has been employed for the determination of Cu, Ni and Cd in various standard metal alloys and natural water samples.     

自动回流萃取-MPT全谱仪测定航空润滑油中磨损金属的含量

将萃取与回流相结合, 建立了一种处理航空润滑油中磨损金属的新方法, 并用MPT全谱仪对磨损金属含量进行了同时检测. 该方法基本上实现了样品处理的全自动化,克服了常用方法的部分缺点, 对Zn, Cd, Cu, Fe和Pb的检出限(3σ)分别为0.084, 0.043, 0.022, 0.052和0.064 μg/g; 相对标准偏差均小于5%(n=5); 回收率为94.5%~107.4%. 对3个润滑油样品的检测结果令人满意.     

Determination of trace amounts of cobalt in water by solid-phase spectrophotometry after preconcentration on a nitroso R salt chelating resin

A sensitive method for the determination of microamounts of cobalt by ion-exchanger spectrophotometry has been developed. The chromogenic agent, Nitroso-R-Salt (NRS), was loaded on an anionic-exchange resin (Amberlite CG-400). The absorbance of the NRS-cobalt complex on the chelating resin was measured at 508 nm. The best conditions for the preconcentration of cobalt on the resin before the spectrophotometric determination were a pH value of 6, temperature of 80 °C, and heating times of 45 or 90 min for 50 and 400 ml of sample, respectively. The detection limits were 27 ng/ml (50-ml samples) and 1.8 ng/ml (400-ml samples). Interference by other metals was investigated. The method is useful for determination of cobalt in natural waters.