Comparative determination of Ba, Cu, Fe, Pb and Zn in tea leaves by slurry sampling electrothermal atomic absorption and liquid sampling inductively coupled plasma atomic emission spectrometry

The comparative determination of barium, copper, iron, lead and zinc in tea leaf samples by two atomic spectrometric techniques is reported. At first, slurry sampling electrothermal atomization atomic absorption spectrometry (ETAAS) was applied. The results of Ba and Pb determination were calculated using the method of standard additions, and results of Cu, Fe and Zn from the calibration graphs based on aqueous standards. These results were compared with the results obtained after microwave-assisted wet (nitric+hydrochloric+hydrofluoric acids) digestion in closed vessels followed by inductively coupled plasma-atomic emission spectrometric (ICP-AES) determination with the calibration by means of aqueous standards. The exception was lead determined after a wet digestion procedure by ETAAS. The accuracy of the studied methods was checked by the use of the certified reference material Tea GBW-07605. The recoveries of the analytes varied in the range from 91 to 99% for slurry sampling ETAAS, and from 92.5 to 102% for liquid sampling ICP-AES. The advantages of slurry sampling ETAAS method are simplicity of sample preparation and very good sensitivity. Slurry sampling ETAAS method is relatively fast but if several elements must be determined in one sample, the time of the whole microwave-assisted digestion procedure and ICP-AES determination will be shorter. However, worse detection limits of ICP-AES must also be taken into the consideration in a case of some analytes.     

Determination of copper, lead, cadmium, zinc, and iron in calcium fluoride and other fluoride-containing samples by means of direct solid sampling GF-AAS

Direct solid sampling graphite furnace AAS (SS-GF-AAS) provides an advantageous alternative to the conventional AAS which requires wet digestion of the samples. This method is suitable for trace element determination in calcium fluoride and other fluoride-containing samples. Matrix effects were studied by using calibration standards, certified reference materials with different matrices and by means of three-dimensional calibration. 3D calibration is suitable for selection of calibration samples for more reliable analyses. Cu, Pb, Cd, Zn, and Fe were determined by means of calibration with variation of sample weight using certified reference materials and suitable fluoride-containing calibration samples. Received: 25 July 1997 / Revised: 15 December 1997 / Accepted: 20 December 1997     

Determination of bioavailable fractions of Zn, Cu, Ni, Pb and Cd in soils and sludges by atomic absorption spectrometry

The single extraction procedures validated by the standards, measurement and testing programme (formerly BCR), extraction with 0.05 mol l⁻¹ EDTA and 0.43 mol l⁻¹ acetic acid, have been applied to reference materials of soils and sludges with certified total values of elements, in order to determine bioavailable contents of Cd, Cu, Ni, Pb and Zn. These soils, which represent uncontaminated pedologically different types of soils from Slovakia and sludges from city water treatment are characterized for the bioavailable fraction of the metals using the procedures followed by SM&T Programme. Concentrations of the elements under the study in the extracts were determined by flame (FAAS) using calibration curves in appropriate extractants and by electrothermal (ETAAS) atomic absorption spectrometry, using technique of standard additions for the evaluation of the results. The accuracy of the extraction procedures and determinations of the elements in the extracts was controlled using CRM 483 certified for EDTA- and acetic acid-extractable contents of Cd, Cu, Ni, Pb and Zn in sewage sludge amended soil.     

Determination of copper, lead, cadmium, zinc, and iron in calcium fluoride and other fluoride-containing samples by means of direct solid sampling GF-AAS

Direct solid sampling graphite furnace AAS (SS-GF-AAS) provides an advantageous alternative to the conventional AAS which requires wet digestion of the samples. This method is suitable for trace element determination in calcium fluoride and other fluoride-containing samples. Matrix effects were studied by using calibration standards, certified reference materials with different matrices and by means of three-dimensional calibration. 3D calibration is suitable for selection of calibration samples for more reliable analyses. Cu, Pb, Cd, Zn, and Fe were determined by means of calibration with variation of sample weight using certified reference materials and suitable fluoride-containing calibration samples. Received: 25 July 1997 / Revised: 15 December 1997 / Accepted: 20 December 1997     

Direct determination of Cd, Cu and Pb in wines and grape juices by thermospray flame furnace atomic absorption spectrometry

The applicability of thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) was evaluated for direct determination of Cu, Cd and Pb in wines and grape juices. The developed procedure does not require preliminary acid digestion of the samples. The optimum conditions for determination of Cu, Cd and Pb in wines were studied and the performance was compared to those typically obtained by flame atomic absorption spectrometry (FAAS). A sample volume of 150 microL was introduced into a heated nickel tube at a flow rate of 0.54 mLmin(-1) and 0.14 molL(-1) HNO(3) was used as sample carrier flowing at 2.5 mLmin(-1) for determining all analytes. The effect of ethanol concentrations on Cu, Cd and Pb absorbance signals were studied. All determinations were carried out by adopting optimized conditions and quantification was based on the standard additions method. Limits of detection (LOD) of 12.9, 1.8 and 5.3 microgL(-1) (n=14) for Cu, Cd and Pb, respectively, were obtained for wine samples (3sigma(blank)/slope, n=14). Relative standard deviations (R.S.D., %) of 2.7, 2.1 and 2.6 for Cu, Cd and Pb, were obtained (n=6) for wine samples. The values determined for grape juice samples were similar to these ones. The analytical throughput was 45 determinations h(-1) and accuracy was checked by addition-recovery experiments.     

Using dried-droplet laser ablation inductively coupled plasma mass spectrometry to quantify multiple elements in whole blood

This paper describes a simple procedure for the direct analysis and determination of multiple elements in dried blood samples on a filter membrane using laser ablation coupled with inductively coupled plasma mass spectrometry (LA-ICP-MS). With this technique, we simultaneously quantified 13 elements in whole blood: Be, Mn, Co, Ni, Tl, Bi, Sb, Pb, Cu, Zn, Ba, Mg, and Cd. The measured accuracies was in agreement with the Seronorm CRM certified values, except for Mn, Zn, Ba and Cd, which presented absolute differences higher than the expanded uncertainty for these elements. The within-run precision was less than 5.7% (relative standard deviation, RSD), except for the analyses of Be, and Mn (8.6% and 11.1%, respectively). The reproducibility (between-run precision) was calculated in terms of the RSD obtained for 12 analyses (i.e., four replicates of each sample in three analytical runs). Apart from Be, Mn, and Zn, the reproducibilities of all the elements listed above ranged between 4.0% and 8.5%. In contrast, for Cd, the concentration obtained was significantly different from the certified value; analyses of this element exhibited low reproducibility. Applying the matrix-matched calibration method, the accuracy for Cd measured was in agreement with both SRM966 and BCR 635; thus, matrix-matched calibration is a practical means of overcoming matrix-enhancement effects for the quantification of Cd. Sample throughput (ca. 5 min per sample) made it possible to rapidly screen a larger number of samples relative to other techniques that require time-consuming sample preparation steps (e.g., removal of a portion of the solid sample or digestion).     

微波消解-ICP-MS法同时测定木薯淀粉中铅、铜、镉、砷、汞的含量

用硝酸-过氧化氢溶液(3+3)作为消解剂,微波消解法处理木薯淀粉等样品,采用电感耦合等离子体质谱法,选择适合的同位素元素,运用碰撞池技术(CCT)降低元素Cu、As的多原子离子干扰,测定样品溶液中Pb、Cu、Cd、As、Hg等元素的含量,各元素线性相关系数为0.9997 ～0.9999,元素的检出限(3sd)分别为pb...     

Multi-element analysis of compost by laser ablation-inductively coupled plasma mass spectrometry

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been applied to multi-element determination in compost samples. Since compost is a heterogeneous mixture of organic and inorganic materials, the influence of sample heterogeneity on the accuracy and precision of analysis was investigated. Several parameters related to the following were studied: laser (energy, laser-beam diameter, preablation. rastering speed, carrier-gas flow rate), sample preparation (use of compacted pellets, grinding time, particle size, sample amount, length of hydraulic press treatment, position of line scan), and the ICP-MS system (quantitative versus semiquantitative analysis, matrix-matched standards and liquid standards calibration). The main causes of imprecision in sample preparation were determined to be particle size and grinding time. The effect of sample heterogeneity on precision was also evaluated by using different test samples (pellets). For Ni, Zn and Pb, the greatest contribution to the total relative standard deviation (R.S.D.) was related to analyte determination. For Mn and Cu, sample heterogeneity and analyte determination contributed equally to the total R.S.D., whereas for Cr, Co, Cd and Hg sample heterogeneity accounted for most of the total R.S.D. A comparison of semiquantitative and quantitative analysis modes showed that better precision and very good agreement with certified reference material was obtained with the latter, but semiquantitative analysis could be a practical alternative. Although accuracy of results was improved with matrix-matched standards calibration the use of standard addition calibration with aqueous standards could be another possibility.     

Determination of Ba, Cd, Cu, Pb and Zn in saliva by isotope dilution direct injection inductively coupled plasma mass spectrometry

Trace elements in small sample volumes of saliva were determined by coupling a high efficiency direct injection nebulizer to inductively coupled plasma mass spectrometry and employing quantification by isotope dilution. Aliquots of 0.4 ml of human saliva were mixed with 0.1 ml of concentrated nitric acid and diluted to 2 ml with water. Sample solutions were spiked with an isotopic solution enriched in 135Ba, 112Cd, 65Cu, 206Pb and 66Zn. The amount of each isotope added to the samples and the measurement procedure were adjusted to attain precise analytical results calculated from the isotope ratios 135Ba/138Ba, 112Cd/114Cd, 65Cu/63Cu, 206Pb/208Pb and 66Zn/68Zn. Data acquisition for Ba, Cu and Zn isotopes was performed for a single sample injection of 50 microl and in another sample injection the Cd and Pb isotopes were measured. Concentrations ranging from 5.0 to 16 microg l(-1) for Ba, from 0.50 to 1.1 microg l(-1) for Cd, from 6.0 to 50 microg l(-1) for Cu, from 0.8 to 18.8 microg l(-1) for Pb and from 46.0 to 230 microg l(-1) for Zn were found in saliva samples. Detection limits of 0.11, 0.03, 0.40, 0.05 and 0.59 microg l(-1) were determined for Ba, Cd, Cu, Pb and Zn, respectively. The concentrations found by isotope dilution were in agreement with those of the completely digested samples quantified by external calibration. The direct analysis of 30 samples per hour was attained with the proposed procedure, avoiding time-consuming digestion steps, contamination risks and matrix effects.     

Ti in dilute slurries of TiO2 nanoparticles by in-torch vaporization sector field inductively coupled plasma-mass spectrometry☆

A Re coil-filament in-torch vaporization (ITV) sample introduction system was interfaced to a sector field inductively coupled plasma-mass spectrometry (SFICP-MS) system. In this first report on an un-optimized ITV-SF-ICP-MS system, detection limits were established using 5 μL volumes of 100 pg mL^− 1 standard solutions, translating to 0.5 pg absolute. Such absolute amounts of a dried solution are near or below the detection limit of many ICP-based techniques. The absolute detection limits for Cd, Eu, Pb, Ti, U and Zn were in the 0.2–2 fg range (or, in the 10's of millions to millions of atoms for Pb, Cd, Zn and Ti, about one million atoms for U and about 800 thousand for Eu). These absolute detection limits along with the ability of ITV to handle minute amounts of discrete samples (thus eliminating memory effects from nanoparticles adhering to the walls of pneumatic nebulization sample introduction systems and from clogging of the mass spectrometer orifice), use of sonicated water-based slurries (that eliminated contamination from acid digestion reagents or from slurry stabilization reagents), and elimination of oxygen containing molecular ion interferences due to use of dry samples enabled concentration determinations of Ti (and consequently of TiO₂) in pg mL^− 1 concentrations of slurries of manufactured, 20 nm diameter TiO₂ nanoparticles.     

Solid-phase extraction and preconcentration of cadmium(II) in aqueous solution with Cd(II)-imprinted resin (poly-Cd(II)-DAAB-VP) packed columns

A novel chelating resin (poly-Cd(II)-DAAB-VP) was prepared by metal ion imprinted polymer (MIIP) technique. The resin was obtained by one pot reaction of Cd(II)-diazoaminobenzene-vinylpyridine with cross-linker ethyleneglycoldimethacrylate (EGDMA). Comparing with non-imprinted resin, the poly-Cd(II)-DAAB-VP has higher adsorption capacity and selectivity for Cd(II). The distribution ratio (D) values for the Cd(II)-imprinted resin show increase for Cd(II) with respect to both D values of Zn(II), Cu(II), Hg(II) and non-imprinted resin. The relatively selective factor (α_r) values of Cd(II)/Cu(II), Cd(II)/Zn(II) and Cd(II)/Hg(II), are 51.2, 45.6, and 85.4, which are greater than 1. poly-Cd(II)-DAAB-VP can be used at least 20 times without considerable loss of adsorption capacity. Based on poly-Cd(II)-DAAB-VP packed columns, a highly selective solid-phase extraction (SPE) and preconcentration method for Cd(II) from aqueous solution was developed. The MIIP-SPE preconcentration procedure showed a linear calibration curve within concentration range from 0.093 to 30 μg l⁻¹. The detection limit and quantification limit were 0.093 and 0.21 μg l⁻¹ (3σ) for flame atomic absorption spectrometry (FAAS). The relative standard deviation of the eleven replicate determinations was 3.7% for the determination of 10 μg of Cd(II) in 100 ml water sample. Determination of Cd(II) in certified river sediment sample (GBW 08301) demonstrated that the interfering matrix had been almost removed during preconcentration. The column was good enough for Cd(II) determination in matrixes containing components with similar chemical property such as Cu(II), Zn(II) and Hg(II).     

Controlling Contamination for Determination of Ultra-Trace Levels of Cr and Ni in Biological Materials in a Conventional Laboratory

The determination of ultra-trace levels of chromium and nickel in biological samples had previously been very difficult due to serious contamination problems in conventional laboratories. Contamination control in a conventional laboratory was studied and contamination due to various sources was minimized systematically. In addition to chromium and nickel, zinc was also determined as an indicator element prone to contamination. Measurements were carried out using electrothermal atomic absorption spectrometry (ETAAS). Contamination from the sample handling steps, digestion vessels, atmospheric fallout, and the effect of the liquid contact area were studied. In the sample handling steps, even simple procedures, such as transferring the sample solution from the volumetric flask by pouring, led to significant contamination due to the large area of liquid contact. This contamination source was eliminated by transferring the sample solution using an automatic pipette. The most suitable method for decontamination of the digestion vessels was steaming with boiling nitric acid as opposed to leaching with nitric acid at room temperature. Quartz was found to be a more suitable digestion vessel material than Teflon-PFA when Cr and Ni were determined. For Zn determination, Teflon-PFA was more suitable. Contamination from atmospheric fallout was highest in the fume hood and was reduced by simply closing the labware into Minigrip® bags before use. The surface area of the labware in contact with the handled liquid volume should be kept at a minimum because even a simple procedure, such as preparing standard solutions in volumetric flasks, can lead to significant contamination if the vessel surface area is too large. Finally, low enough contamination was achieved so that the total procedure blanks were below the instrumental detection limits for Cr and Ni.     

Determination of cadmium, zinc, nickel and cobalt in tobacco by reversed-phase high-performance liquid chromatography with 2-(8-quinolylazo)-4,5-diphenylimidazole as a chelating reagent.

A sensitive and selective method has been developed for the simultaneous determination of cadmium, zinc, nickel and cobalt. The method is based on the chelation of metal ions with 2-(8-quinolylazo)-4,5-diphenylimidazole (QAI) and the subsequent reversed-phase (RP) high-performance liquid chromatographic separation and spectrophotometric detection of the metal chelates. The chelates were separated on an RP column with acetonitrile-water containing ethylenediamine tetraacetic acid and sodium acetate (pH 7.5). Though Zn(II) and Cd(II) chelates with azo compounds were generally labile in the RP column, these chelates with QAI were successfully detected. When analyses were carried out at 575 nm and at 0.001 absorbance unit full scale, the peak height calibration curves were linear up to 2.0 ng for Cd(II), 2.4 ng for Zn(II), 0.14 ng for Ni(II) and 0.72 ng for Co(II) in 100-microL injections, respectively; the detection limits (3sigma, three times of the standard deviation for the blank signal) for Cd(II), Zn(II), Ni(II) and Co(II) were 4.8, 24, 2.4 and 7.2 pg in 100 microL of injected solution, respectively. The proposed method was successfully applied to the analysis of tobacco without any preliminary concentration or separation.     

Vapor phase matrix extraction of high purity di-boron trioxide and trace analysis using electrothermal AAS

A method has been developed for the determination of Al, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Sb, Sn and Zn at trace levels in high purity di-boron trioxide using ETAAS. The boron trioxide matrix was eliminated as trimethyl borate ester in a multiplex vapor phase matrix extraction (MVPME) device using a mixture of glycerol and methanol. In this MVPME device, in situ reagent purification, sample digestion and simultaneous matrix elimination were achieved by a single step in closed condition, which in combined effect reduce the process blanks. The matrix extraction procedure allows determination of trace elemental impurities by electrothermal atomic absorption spectrometry (ETAAS) with fast furnace analysis (without an ashing step and modifier) and calibration against aqueous standards. The performance and accuracy of the vapor phase matrix elimination technique are compared to those of suprapur grade hydrofluoric acid solution in two ways; (i) matrix separation as BF₃ over hot plate and (ii) in situ matrix elimination inside graphite furnaces. The method detection limits calculated from blank samples are in the range of 0.5 (Ni) and 2.9 (Al) ng g⁻¹. Thus the MVPME-based sample preparation approach is well suited for the trace analysis of high purity di-boron trioxide used in microelectronics applications.     

Direct determination of iron in urine and serum using graphite furnace atomic absorption spectrometry

A simple, rapid and low-cost method for the routine determination of iron in urine and serum using graphite furnace atomic absorption spectrometry is described which may provide an alternative to the more widespread automated spectrophotometric methods. The urine and serum samples were simply diluted with water prior to analysis. Matrix modification was found to be redundant. The standard additions technique or the use of matrix matched standards (addition calibration) was found to be unnecessary and, therefore, the calibration was performed using aqueous standards. For serum analysis the degree of dilution could be reduced by using the less sensitive 302.0-nm resonance line, yielding more precise determinations, and for urine analysis, interferences were eliminated by means of a L'vov platform. The interferences that exist in the presence of nitric acid are also discussed. Finally, the presence of background absorption was investigated by means of Zeeman effect atomic absorption.     

Application of laser ablation inductively coupled mass spectrometry (LA-ICP-MS) for the determination of major, minor, and trace elements in bark samples

The large surface area of barks from many tree species enables the effective accumulation of pollutants. Therefore, the analysis of bark material will provide useful information about the degree of pollution of a certain region. The determination of main, minor, and trace elements (Al, Ca, Cd, Ce, Cr, Cu, Fe, Mn, P, Pb, S, Ti and Zn) in bark was performed with an Nd:YAG laser coupled to an ICP-MS system. Bark standards for the calibration by laser ablation ICP-MS were prepared from different bark layers which differ for some relevant elements in concentrations. Four digestion procedures for the decomposition of the standard pellets, the numbers of laser shots per sample and of samples per region necessary have been investigated. Representative results were obtained for 5 or more samples taken from different individuals of one species of a sampling area and the averaged element concentrations of 10 separately placed laser shots for each sample. Laser ablation ICP-MS was applied for the characterization of real bark samples from different regions with high and low pollution burden. It was shown that the method is well suited to characterize different degrees of environmental impact. Anthropogenic sources were responsible for the higher concentrations of most of the elements under investigation.     

Application of Short Sequential Extraction Procedure（SSEP） for the Determination of Zn, Cu, and Cd Contents in Riverbed Sludge in Hejiagou, Harbin, China

IntroductionThe environment is contaminated by high concen-trations of metals from different sources such as conta-minated soils[1—10], sediments[11—15], and sewage orindustrial sludge[16—20]. However, there has been noreport on the determination of he…     

Determination of Cd and Zn by isotope dilution-thermal ionisation mass spectrometry using a sequential analysis procedure

Isotope dilution-thermal ionisation mass spectrometry (ID-TIMS) was used to examine the certified Cd and Zn content of 4 Certified Reference Materials (CRMs); 2 soils: GBW07401 and GBW07405, 1 plant CRM060 and an animal tissue SRM1566a. The CRMs were chosen to be of contrasting origin and Cd:Zn content. Three digestion procedures were compared: (i) an open tube aqua regia procedure (ii) microwave digestion using Teflon bombs and (iii) hydrofluoric acid (HF) digestion using PTFE bombs. The Cd and Zn levels obtained using ID-TIMS all fell within the published certified range for the CRMs. This was the case regardless of the digestion procedure used, although HF digestion tended to yield marginally higher levels than the other procedures and in one instance, Cd in GBW07401, was significantly different (P<0.05) from the certified range. A filament loading procedure was developed, to allow sequential analysis of Cd and Zn on the same single filament during thermal ionisation mass spectrometry analysis. The sequential analysis technique was evaluated to ensure that Zn did not fractionate during Cd analysis and there was no inter-element interference. No marked difference in the precision and accuracy of the isotope ratio measurements were obtained from sequential element analyses on the same filament when compared to individual element analyses for a range of standard solutions or for sample digests. The most efficient procedure in terms of costs and productivity for future work of this kind would be a combination of microwave digestion and sequential analysis of Cd and Zn on the same filament.     

Application of laser ablation inductively coupled mass spectrometry (LA-ICP-MS) for the determination of major, minor, and trace elements in bark samples

The large surface area of barks from many tree species enables the effective accumulation of pollutants. Therefore, the analysis of bark material will provide useful information about the degree of pollution of a certain region. The determination of main, minor, and trace elements (Al, Ca, Cd, Ce, Cr, Cu, Fe, Mn, P, Pb, S, Ti and Zn) in bark was performed with an Nd:YAG laser coupled to an ICP-MS system. Bark standards for the calibration by laser ablation ICP-MS were prepared from different bark layers which differ for some relevant elements in concentrations. Four digestion procedures for the decomposition of the standard pellets, the numbers of laser shots per sample and of samples per region necessary have been investigated. Representative results were obtained for 5 or more samples taken from different individuals of one species of a sampling area and the averaged element concentrations of 10 separately placed laser shots for each sample. Laser ablation ICP-MS was applied for the characterization of real bark samples from different regions with high and low pollution burden. It was shown that the method is well suited to characterize different degrees of environmental impact. Anthropogenic sources were responsible for the higher concentrations of most of the elements under investigation. Received: 26 April 1999 / Revised: 24 August 1999 / /Accepted: 28 August 1999     

Simultaneous Determination of Cd(II), Cu(II), Pb(II) and Zn(II) in Human Plasma by Potentiometric Stripping Analysis

In this paper, Potentiometric Stripping Analysis (PSA) was simultaneously used to determine the concentrations of trace metals (Zn, Cd, Pb and Cu) in human plasma. The metal ions were concentrated as their amalgams on the glassy carbon surface of a working electrode that was previously coated with a thin mercury film and then stripped by a suitable oxidant. The selection of the experimental conditions was made by using the experimental‐designed methodology. The optimum conditions of the method includes a 0.2 M HAc‐NaAc buffer mixture (pH 4.5) as supporting electrolyte, and an electrolysis potential of‐1220 mV. The limits of detection (LOD) were obtained 1 μg L^?1 for Zn(II) and Pb(II), 0.5 μg L^?1 for Cu(II) and 2 μg L^?1 for Cd(II) in the studied medium. The good recoveries were obtained for the analysis in human plasma. The method was applied to blood samples, using the method of standard additions and the results were compared with Inductively Coupled Plasma‐Atomic Emission Spectrometry (ICP‐AES) as reference method. Furthermore, a simple digestion protocol of samples is investigated compared to the conventional digestion method.