Trace Elements In Samples Research Articles

The Potential of Helichsryum splendidum (Thunb.) Less. for the Restoration of Sites Polluted with Coal Fly Ash.

The disposal of coal fly ash (CFA) generated from coal-fired power stations has serious impact on the ecosystem, by converting large pieces of land to barren ash dams with the potential to contaminate groundwater, surface water, air and soil. The aim of this study was to clarify the potential of phytoremediation using Helichrysum splendidum (Thunb.) Less. in areas polluted by CFA through conduction of pot trial experiments for 14 weeks. Plants of the same age were cultivated in CFA to assess their growth, photosynthetic rate and tolerance towards metal toxicity. This study revealed that the CFA was moderately polluted with heavy metals, and a lower photosynthetic rate was recorded for the CFA plants in comparison to the controls (plants grown in soil). Although the CO2 assimilation rate was lower for the CFA plants, increased growth was recorded for all the plants tested. Inductively coupled plasma mass spectrometry (ICP-MS) was used to quantify the amount of trace elements in samples and parameters including translocation factor (TF) and bioconcentration factor (BCF) were used to evaluate the phytoremediation potential of H. splendidum (Thunb.) Less. The results revealed that higher concentrations of Cd, Co, Cr, Cu, Mn and Pb were accumulated in the roots, while As, Ni and Zn were found in the shoots. Elements including As, Cr and Zn reported TF values above 1, indicating the plants' phytoextraction potential. The BCF values for As, Cu and Zn were 1.22, 1.19 and 1.03, indicating effectiveness in the phytostabilization processes. A removal rate efficiency ranging from 18.0 to 56.7% was recorded confirming that, H. splendidum (Thunb.) Less. can be employed for restoration of CFA dams.

Application research of monochromatic micro x‐ray fluorescence in glass physical evidence traceability

AbstractMicro‐x‐ray fluorescence (μ‐XRF) is a commonly used elemental analysis technique for glass physical evidence in forensic cases, which can detect major and trace elements in samples and potentially identify glass fragments according to the differences in elemental composition. However, when a sample is irradiated with polychromatic x‐rays, bremsstrahlung scattering from the source radiation provides noise in the fluorescence spectrum and affects the detection results. To improve the signal‐to‐noise ratio of the fluorescence spectrum, a Mμ‐XRF spectrometer constructed under the low‐power Mo target x‐ray tube condition was used to analyze ten kinds of common glass fragments. The application of laboratory Mμ‐XRF analysis in single‐point detection of tiny glass materials was studied. Experimental results show that the detection limit of Sr element was 51 μg/L, and the spectrometer can distinguish different types of small glass fragments according to the fluorescence spectrum information.

Provenance Analysis in the Nima Basin during Paleogene and Its Implications for the Decline of the Tibetan Central Valley.

It is unclear what caused the Bangong Nujiang suture zone in the central Tibetan plateau to rise from less than 2 km in early Cenozoic to more than 4 km at present. The zircon U-Pb ages and trace elements of samples from the Niubao Formation in the Paleogene of the Nima basin were analyzed and tested. Combined with the isostasy theory, the surface uplift height of the Nima Basin during the Cenozoic period was calculated. The zircon U-Pb age results of the Niubao formation are consistent with the ages of the Lhasa terrane on the south side of the basin, the Qiangtang terrane on the north side, and the uplift in central. The zircon Eu/Eu* results show that the crust in central part of Tibetan plateau thickened by ∼20 km in Paleogene, resulting in ∼3 km surface uplift. Sediments created a total of about 1 km of surface uplift throughout the Paleogene, and the deposition rate began to slow down significantly at ∼40 Ma. Therefore, it is inferred that in the early Cenozoic, the uplift of the valley was mainly caused by sedimentation. With the continuous downward subduction of the Indian plate, at about 40 Ma, factors such as crustal shortening dominated the uplift of the central valley, and the uplift caused by deposition only accounted for a very small part. In general, the uplift of the Central Valley in the Paleogene was mainly affected by crustal shortening, but a quarter of the surface uplift was caused by the accumulation of sediments.

Ecological risk assessment of soil samples from Sudanese gold-mining regions using neutron activation analysis

ABSTRACT This study sought to assess the concentrations of major and trace elements in soil samples taken from gold-mining sites in Sudan, with the ultimate aim being to explore the degree of pollution and risk caused by trace metals in this region. The concentrations of major elements (Al, Fe, Ca, Na, Ti, K, Mn, Ba) and trace elements (Cr, V, Zn, Rb, Co, Sc, Hf, Th, Br, As, U, Cs, Ta, and Au) were established using neutron activation analysis (NAA), while the concentrations of Cu and Ni were determined using atomic absorption spectroscopy (AAS). This revealed the presence of various major and trace elements in the samples, with some elements showing a moderate level of enrichment in certain locations. Overall, the samples were found to be unpolluted to slightly polluted, except for one sample that showed a slight-to-moderate level of contamination for certain elements. The geo-accumulation index, contamination factor, and multi-element indexes were used to assess the degree of contamination, while the potential ecological risk index was used to evaluate an ecological risk assessment. Pollution indicators showed that the soils considered in the study are at most slightly to moderately polluted by major and trace elements. This study therefore contributes to our understanding of the presence of major and trace elements, the degree of contamination, and the ecological risk presented by trace metals in the soil of gold-mining areas.

Identification of Sources and Mobilization of Trace Elements in Shallow Groundwater of the Upper Ganges River Basin

The concentration of trace metals in groundwater is still not within the usual standards established by the national and international monitoring authorities. This study aims to evaluate the sources and distribution of trace metals in the shallow aquifer water of the Ganges River basin in the Bangladesh area. A total of 40 groundwater samples were collected and investigated for 11 trace elements and some selected water parameters followed by sophisticated methods. The results presented that three metals, viz. Fe, Mn, and Pb crossed the limit of WHO standard in most of the samples (70-100%), representing severe human health hazards. Besides, the samples are slightly acidic to basic and highly mineralized by divalent cations and bicarbonate because total hardness was found very high. To assess factors affecting the trace metal loads in groundwater samples and determine their possible sources and mobility, multivariate statistical techniques, including Pearson’s correlation coefficient, principal components analysis, and dendrogram cluster analysis are performed. Results revealed that sources of trace elements were identified to be geologic and little from human activities, i.e., application of agrochemicals, excess water mining, and industrial wastewater. It was recognized that the elevated concentration of trace elements in samples was caused by geogenic factors rather than manmade activities. Groundwater in this area poses a large threat due to high levels of trace metals, without any purification, it is essential to avoid this water for drinking. It advised that the groundwater quality should be constantly monitored for sustainable water quality management in the study zone.

Detection of Y, La, Yb, and Dy elements in rare earth ores by double-pulse laser-induced breakdown spectroscopy

The sensitivity of double-pulse laser-induced breakdown spectroscopy (DP-LIBS) in the detection of trace elements in samples was confirmed to be superior to that of single-pulse laser-induced breakdown spectroscopy (SP-LIBS). However, DP-LIBS is not economical because it requires two lasers. A DP-LIBS system based on beam splitting was proposed in this work, and the experimental equipment was used to analyze Y, La, Yb, and Dy elements in rare earth ores. The comparison of spectral line intensities and sensitivities of rare earth elements in rare earth ore samples between DP-LIBS and SP-LIBS was studied. The results show that the enhancement of the spectral line signal intensity of DP-LIBS is more than two times compared with that of SP-LIBS. The time evolution of signal intensities of four rare earth element characteristic lines (Y II 437.49 nm, La II 433.37 nm, Yb II 328.94 nm, and Dy II 353.17 nm) was given. The enhancements of signal intensities were found to be due to that the plasma temperature of DP-LIBS is increased by more than 500 K. The limits of detection of Y, La, Yb, and Dy were 40.97, 104.09, 47.13, and 56.25 ppm for SP-LIBS and can be reduced to 21.19, 56.93, 28.69, and 36.41 ppm for DP-LIBS. It is showed that DP-LIBS based on a single Nd:YAG laser can better improve the signal intensity and sensitivity of Y, La, Yb, and Dy elements in rare earth ore samples.

Study on Organic Matter Enrichment and Reservoir Characteristics of Permian Longtan Formation Shale in Southeast Sichuan

The study of reservoir space development characteristics and the geochemical parameters of the Permian Longtan Formation in the southeast of the Sichuan Basin at Well X1 was analyzed by using core observations, optical thin-section observations, Ar-ion polishing, scanning electron microscopy, and nitrogen adsorption tests. Major and trace elements of samples, the V/Cr, U/T, enrichment coefficients EF (Mo) and EF (U), chemical alteration indexes CIA and Sr/Cu, and Mo, P, and other index values of different samples were calculated based on the test of organic geochemical parameters. The depositional environment of the Longtan Formation in the study area was systematically analyzed. The Longtan Formation was in a warm and humid climate during the deposition period. The main body of the sedimentary water was in an oxygen-depleted state, and a portion of it was in an oxidized state with high biological productivity. Therefore, it had a small deposition rate. The clay mineral content and organic matter content in the sample played a major role in controlling the development of reservoir space. The content of clay minerals in the sample was high, and it was mainly chlorite and a mixed layer of illite/smectite. Under a microscope, it was observed that the mixed layer of flake illite/smectite and chlorite aggregate mostly developed interlayer pores or microfractures, which played a positive role in the specific surface area and pore volume of the sample.

Determination of trace elements in liquid samples with organic matrix by arc atomic emission spectrometry

Conditions for the analysis of liquid samples on a MFS-8 spectrometer upgraded with a MAES photodiode array by arc atomic emission spectrometry with dry residue technique are specified. It is shown that optimization of the electrode shape along with the method of calculating the intensity of the spectral line and time of the base exposure leads to the expansion of the operating range of calibration curves. The arc plasma parameters (temperature and electron density) are similar when the spectra of dry residues of aqueous solutions, saliva, blood serum, and dry wine are excited. This provides direct (without digestion) determination of trace elements in these samples with the detection limits at a level of μg/liter. When a sample of vegetable oil is deposited on the electrode, it is likely to be absorbed in depth and does not enter the arc plasma in full, which makes the direct analysis impossible. Nevertheless, the determination of trace elements in oils by the dry residue technique is possible after acid digestion of the sample.

Estimating the Level of Some Trace Elements in Samples of Canned Foods Spread in the Markets of Ramadi City - Western Iraq

Canned food is becoming increasingly popular in the market. In order to assess the level of concentrationof some important elements in samples of these foods, ten different types of canned food were studied. Theconcentration level of nine elements (potassium, magnesium, calcium, iron, manganese, copper, zinc, leadand cadmium) was measured using atomic absorption spectroscopy. The results showed that the highestconcentrations of potassium, magnesium, zinc and lead were in the chickpeas sample. While the highestconcentration of calcium and manganese appeared in the fish sample. As for the elements of iron andcopper, the highest concentration of them was in the olive sample. In the mushroom sample, the highestconcentration of cadmium was shown.

Ice sheets mobilize trace elements

Earth’s two remaining ice sheets, also called continental glaciers, are more active geochemists than we previously knew, according to a new study. Researchers led by Jon Hawkings, a biogeochemist at Florida State University and the German Research Center for Geosciences, measured the abundance of 17 trace elements in samples of meltwater from the Greenland Ice Sheet and a lake beneath the Antarctic Ice Sheet. They found that these water samples are more enriched in important micronutrients such as iron compared with rivers and the surrounding ocean ( Proc. Natl. Acad. Sci. U.S.A. 2020, DOI: 10.1073/pnas.2014378117 ). The trace elements can be found fully dissolved or suspended as nanoparticles, and they likely come from the bedrock beneath the frozen giants. That’s because ice sheets are “natural bulldozers” that pulverize landscapes as they move, and water trapped in subglacial lakes can liberate minerals from the surrounding rock, Hawkings says. “We didn’t have

Improving the Detection Sensitivity for Laser-Induced Breakdown Spectroscopy: A Review

Laser-induced breakdown spectroscopy (LIBS) is fast, on-line, causes little sample damage, and can be applied in remote field locations. In recent years, LIBS has been widely used in many fields of scientific research for element detection. Further application of LIBS is limited by the strong matrix effect, poor repeatability, and relatively weak detection sensitivity. The detection sensitivity is an important factor and needs to be improved for LIBS detection of minor or trace elements in samples. A variety of methods have been developed for this. In this invited review paper, we discusse improvements in the LIBS detection sensitivity achieved with physical enhancement methods, chemical enhancement methods, mathematical methods, and combinations of multiple methods. We discuss the enhancement mechanisms, sensitivity improvements, configurations, and effects of key factors for various methods. The advantages, disadvantages, and real-time capabilities of these methods are reviewed. Finally, new trends and future perspectives for LIBS as an efficient analytical tool are highlighted.

Level of trace elements in serum and toenail samples of patients with onychocryptosis (ingrown toenail) and onychomycosis

BackgroundOnychocryptosis (ingrown toenail) and onychomycosis are common pathologies of the toenail and affecting many people. Since levels of trace elements have been shown to vary in certain diseases, in the presented work, chromium (Cr), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), selenium (Se), and zinc (Zn) levels of toenail and serum samples of healthy individuals and patients with onychocryptosis and onychomycosis were compared. MethodsSerum and toenail samples of 88 voluntary subjects (healthy n = 24; onychomycosis n = 24; onychocryptosis n = 40) aged between 19–80 years were collected. Levels of trace elements in the samples were analyzed by using an inductively coupled plasma-optical emission spectrophotometer (ICP-OES Thermo iCAP - 6000). The differences in medians between the groups for elements were evaluated with Kruskal -Wallis H test with post hoc for pairwise comparisons in SPSS 18. ResultsMg (p < 0.001) and Mn (p = 0.002) levels were significantly increased whereas Zn (p = 0.011) level was decreased in toenails of patients with onychomycosis compared to healthy subjects. Although Mg and Mn levels were higher in female subjects with onychomycosis (p = 0.001; p = 0.019), Mn was only increased in male subjects (p = 0.015). Mg was the only trace element found to be independent of sex, age, and smoking status in patients with onychomycosis. However, no significant difference has been found in serum trace element levels neither between any groups nor toenail trace element levels of patients with onychocryptosis and healthy subjects. ConclusionAs a response of the human body to pathogens like fungi in toenails, Mg, Mn and Zn levels vary. Especially the role of Mg ions in onychomycosis needs to be investigated more specifically.

Determination of trace elements in high-purity quartz samples by ICP-OES and ICP-MS: A normal-pressure digestion pretreatment method for eliminating unfavorable substrate Si

The analysis of siliceous matrix samples may adopt a two-step pretreatment, which includes melting with ammonium hydrogen fluoride and redissolving with nitric acid. However, the residual of substrate silicon unfavorable to the determination of trace elements in the samples due to serious matrix effects. Here, a new digestion method using simultaneously both ammonium bifluoride and nitric acid under normal pressure was developed for high-purity quartz sand sample. The digestion pretreatment is a two step process: melting/dissolving with both ammonium bifluoride and nitric acid at 200 °C for 2 h, and evaporating the solution at 250 °C to dryness. As confirmed by XRD analysis, silicates in the sample were converted to (NH4)3SiF6NO3 in the melting/dissolving step. TGA analysis shows that the generated (NH4)3SiF6NO3 could be decomposed and evaporated completely at 250 °C, which ensured a complete removal of silicon by the followed evaporation of the solution at 250 °C. As a result, the followed ICP-OES and ICP-MS analysis needed a solution dilution of only 100 times for the determination of Ca, Mg, Al, Rb, Ba, REE and other trace elements. The new method was applied to the analysis of three certified reference materials, and the results were well consistent with the standard value with RSD% values between 0.62% and 9.73%. Therefore, this method can be applied to the analysis of trace elements in high purity silica-based samples, with the advantages of time-saving, small dilution factor (only 100 times) and low detection limit.

Determination of trace elements in samples with high salt content by inductively coupled plasma mass spectrometry after solid-phase preconcentration

A method for solid-phase extraction (SPE) using nanometer-sized silica modified with N-[2-aminoethyl]-3-aminopropyltrimethoxysilane (AAPTS) coupled with inductively coupled plasma mass spectrometry (ICP-MS) was proposed in this work for analysis of Ni(II), Cu(II), Ga(III), Cd(II), Pb(II), and Bi(III). It was noted from zeta potentials that the absorptivity of the modified nanoparticles could be partially attributed to the electrostatic interactions of amino groups in alkaline conditions. Elemental ions were adsorbed at a pH of 9.0 and then eluted with 1 mol/L nitric acid and 0.5% citric acid. Effects of enrichment time, sample flow rate, and coexisting ions were also investigated. Using the same instrument conditions, higher recovery of elements in synthetic seawater after solid-phase extraction was achieved compared to directly diluting 50 times with 1% nitric acid. This method was successfully applied for the determination of trace metal ions (Ni, Cu, Ga, Cd, Pb, and Bi) in milk powder samples.

Uncertainties in measuring trace amounts of cobalt and europium with low-flux neutron activation analysis

Neutron activation analysis is widely used for identification of elements and their quantities even in trace amounts in the samples of almost any type. The challenges in detecting trace amounts of particular elements are often associated with the neutron flux produced at the research reactors. Low-flux neutron activation analysis usually presents the biggest challenge when analyzing trace quantities of elements with lower magnitude of radiative capture cross-sections. In this paper, we present the methodology and the quantified uncertainties associated with the detection of trace amounts of cobalt and europium, using as an example concrete aggregates. Recent growing interest is in improving structural concrete (increasing its strength but reducing its activation in nuclear power plant environments). Aside from buildings, structural concrete is also used as a biological shield in nuclear power plant that become radioactive after exposure to neutron flux. Due to radiative capture interactions, artificial radionuclides are generated to high enough concentrations that classify concrete as low-level radioactive waste at the time of the plant's decommissioning. Disposal of this concrete adds to the expense of nuclear power plant financing and its construction. Three radionuclides, 60Co, 152Eu, and 154Eu, account for 99 % of total residual radioactivity of nuclear power plant decommissioned concrete. IAEA document RS-G-1.7, Application of the Concepts of Exclusion, Exemption, and Clearance, specifies clearance levels of radionuclides specific activities: a specific activity lower than 0.1 Bqg-1 for 60Co and 152Eu, and 154Eu allows for a concrete to be recycled after decommissioning of the nuclear power plant. Therefore, low-flux neutron activation analysis is used to test the detection limits of trace elements in samples of cement, coarse, and fine concrete aggregates. These samples are irradiated at the University of Utah's 100 kW TRIGA Reactor at power levels of 10 kW, 30 kW, and 90 kW, with the corresponding thermal neutron flux values of 1.5?108, 7.3?109, and 3.76?1011 cm-2s-1.The samples are irradiated for time periods of 1, 3, 30, 60, and 120 minutes. Different power levels and different irradiation times are used to find if there is a threshold set of neutron activation analysis parameters in detecting trace amounts of these isotopes. Each of the samples is counted on a Canberra BEGe high purity germanium detector. Cement samples are concurrently irradiated with a National Institute of Standards and Technology coal fly ash standard reference material and coarse and fine aggregates with Montana soil standard reference material to accurately quantify the mass concentration of the isotopes in concrete samples. Final results show that reactor power, irradiation, and detector measurement times are heavily correlated to finding the optimum combination for a low-flux neutron activation analysis approach in detecting trace contents of elements, specifically cobalt and europium.

Energy dispersive X-Ray fluorescence spectrometric study of compositional differences in trace elements in dried Moringa oleifera leaves grown in two different agro-ecological locations in Ebonyi State, Nigeria

This study investigated the compositional differences in trace elements in M. oleifera leaves grown in two different agro-ecological locations in Ebonyi State, Nigeria. Fresh samples of dried M. oleifera leaves were collected and analysed for P, S, K, Ca, Mn, Ti, Cu, Mo, Fe, Zn, Ni, Re, Eu and Pb using Energy Dispersive X-ray fluorescence (ED-XRF) spectrometry, following standard procedures. The results showed varying amounts of the studied elements in the samples from the two locations, with relatively high amounts of Pb. When the mean content of P, K Ca, Mn, Cu, Fe and Zn in the samples where compared to their daily requirements for adults and the expected quantity of M. oleifera leaves an adult will eat to achieve the daily requirements, it was concluded that the leaves could serve as veritable source of these elements to local consumers. Levels of significant differences in the concentrations of the trace elements in samples of M. oleifera leaves grown in both locations were tested at 95% confidence level ( α = 0.05) using F- and student’s t -tests. The outcome showed that although there are compositional differences in the amounts of the elements studied in the samples, these differences are not significant ( t exps < t crits ) at 95% confidence interval. Keywords: trace elements, daily requirements, M. oleifera , ED-XRF spectrometry, Mgbabor, Okposi-Okwu

First results of the application of scanning XRF analysis with synchrotron-radiation beams from the VEPP-3 to study the spatial distribution of trace elements in samples of stratiform chromite ores

A sample from chromite horizon UG1 of the platiniferous Bushveld complex (South Africa) is studied by scanning X-ray fluorescence (XRF) microanalysis using synchrotron-radiation beams from the VEPP-3 storage ring. The sample contains plagioclase and chromite layers 3–5 mm in thickness. The experimental study is conducted at excitation energies of 15 and 30 keV; the spot size of the excitation radiation is 0.1 ± 2 mm; and the scanning step is 100 µm. The distribution profiles of more than 20 trace elements over the surface of the sample are obtained.

Quantitative mapping of trace elements in agate using LA-ICP-MS

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is an optimized technique for the quantitative mapping of trace elements on geological materials. Agate is an aggregate of microcrystalline silica showing a variety of colorful bands due to the species and concentrations of transition metals and is thus an appropriate sample to test the availability, efficiency, and detection limit of LA-ICP-MS trace element mapping. Two fortification agate samples selected for elemental mapping are characterized by the colorful and bluish banding layers, respectively. The colorful agate sample consists mainly of two growth zones varying in color from pale orange-red brown to gray tones, whereas the blue agate sample simply shows alternating blue and white bands. Two different types of mineral inclusions, Fe oxide/hydroxide and hollandite (Ba(Mn4+ 6Mn3+ 2)O16), were identified in the inner and outer halves of the former sample, respectively. The distribution patterns of eight trace elements in these samples, including Al, Co, Cr, Cu, Fe, Mn, Ni, and Ti, were investigated, using both electron microprobe and LA-ICP-MS. Aluminum and Fe are the most abundant trace elements in both agate samples up to 5000 ppm although their concentrations in the colorful agate sample are an order of magnitude higher than those in the blue agate sample. The concentrations of other elements in the agate samples are several parts per million levels. The quantitative maps of the colorful agate sample have shown that Fe was mainly distributed in the inner half, but Al, Cu, and Mn in the outer half. In particular, Fe and Mn were primarily concentrated as small spots. On the other hand, the oscillatory zoning patterns are apparent in the quantitative maps of the blue agate sample, showing a correlative relationship between Al and Ti but an antithetic relationship between Al and Fe. The Al and Fe distribution patterns of the colorful agate sample are reproduced in the Al Kα and Fe Kα X-ray maps, but not clear in blue agate. Quantitative elemental maps using LA-ICP-MS are privileged to visualize trace elements distributions.

Chelating resin immobilizing carboxymethylated polyethyleneimine for selective solid-phase extraction of trace elements: Effect of the molecular weight of polyethyleneimine and its carboxymethylation rate

The effect of the molecular weight of polyethyleneimine (PEI), defined as a compound having two or more ethyleneamine units, and of its carboxymethylation rate (CM/N), represented by the ratio of ion-exchange capacity to the amount of N on the resin, on the selective solid-phase extraction ability of the chelating resin immobilizing carboxymethylated (CM) PEI was investigated. The chelating resins (24 types) were prepared by immobilization of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, PEI300 (MW=ca. 300), and PEI600 (MW=ca. 600) on methacrylate resins, followed by carboxymethylation with various amounts of sodium monochloroacetate. When resins with approximately the same CM/N ratio (0.242−0.271) were used, the recovery of Cd, Co, Cu, Fe, Ni, Pb, Ti, Zn, and alkaline earth elements increased with increasing the molecular weight of PEIs under acidic and weakly acidic conditions; however, the extraction behavior of Mo and V was only slightly affected. This was probably due to the increase in N content of the resin, resulting in an increase in carboxylic acid groups; the difference in the molecular weight of PEIs immobilized on the resin exerts an insignificant influence on the selective extraction ability. The CM/N ratio considerably affected the extraction behavior for various elements. Under acidic and neutral conditions, the recovery of Cd, Co, Cu, Fe, Ni, Pb, Ti, and Zn increased with increasing CM/N values. However, under these conditions, the recovery of alkaline earth elements was considerably low when a resin with low CM/N ratio was used. This is presumably attributed to the different stability constants of the complexes of these elements with aminocarboxylic acids and amines, and to the electrostatic repulsion between the elements and the protonated amino groups in the CM-PEI. The recovery of Mo and V decreased or varied with increasing CM/N values, suggesting that the extraction of these elements occurred mainly by the anion-exchange reaction. For the separation and preconcentration of trace elements in samples containing large amounts of alkali and alkaline earth elements, the CM-PEI600 resin with CM/N=0.131 (Cu(II) extraction capacity, 0.37mmolg−1) was found to be the most suitable because it scarcely extracts alkali and alkaline earth elements under acidic and neutral conditions. This resin proved to be convenient for separating and preconcentrating Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn in the certified reference materials (EnviroMAT EU-L-1 wastewater and ES-L-1 ground water) and commercially available table salt.

Sample preparation in crucible atomizers for determining cadmium and lead in natural water by atomic absorption

In the determination of trace elements in samples of natural water in crucible electrothermal atomizers, it is promising to carry out two consecutive stages of sample preparation, i.e., the dynamic preconcentration of dissolved forms of elements on a solid sorbent with the simultaneous separation of suspended matter and subsequent thermal decomposition of the concentrate with fractional evaporation-condensation of an analyte. This approach allows us to reduce the risks of introducing impurities and losses of elements. The first stage of sample preparation can be executed under field conditions out of the laboratory.