Fractionation of metals and metalloids by chemical bonding from particles accumulated by electrostatic precipitation in an Argentine thermal power plant

A study was undertaken to evaluate the distribution of Al, As, Cr, Cu, Fe, Mn, Ni, Pb, Ti, V and Zn in fly ashes collected in the electrostatic precipitator of a thermal power plant in San Nicolás (Argentina). Five samples were collected during one week of operation. For the fractionation, the scheme applied consisted in extracting the elements in four fractions namely (i) soluble and exchangeable elements; (ii) carbonates, oxides and reducible elements; (iii) bound to sulfidic metals; and (iv) residual elements. Metals and metalloids at μg g^− 1 level were determined in each fraction by inductively coupled plasma optical emission spectrometry (ICP OES). For validation, a standard reference material (SRM 1633 coal fly ash) from NIST was subjected to the same chemical sequential extraction procedure that the samples. X-ray diffraction powder (XRD) analysis and scanning electron microscopy (SEM) were used to characterize the major minerals present in the matrix. Total analyte concentration (in μg g^− 1) varied from 10.6 for Pb to 17,622 for Al. Minimum and maximum concentrations (in μg g^− 1) found in individual samples in the four fractions were: Al, 92.7–9668; As, < 0.3–143; Cr, 2.0–10.4; Cu, < 0.2–35.6; Fe, < 0.3–4992; Mn, < 0.1–128; Ni, < 0.3–139; Pb, < 0.5–9.1; Ti, < 0.3–2243; V, 17.0–112.9; and Zn, < 0.1–68.2. The leachability of the 11 elements under study proved to be different. Low percentages of Al (1%), V (7%) and Cr (8%) were detected in the most bioavailable fraction. Arsenic was found to be most abundant in the non-silicate phase, represented by the second and third fractions, while Cr, Fe, Ni, Pb and Zn were mostly associated to the residual fraction.     

Occurrence and distribution of metals and porphyrins in Nigerian coal minerals

The metal contents of Nigerian coal minerals were analyzed using an atomic absorption spectrophotometer. Calcium, Na, and Fe occurred as the major elements with concentrations ranging from 9 782 μg/g for Ca to 432 μg/g for Na whereas K, Mg, Mn, Ni, Cr, Zn, Pb, and Cu, which occurred at trace levels ranged from 673.73 μg/g for Mg to 2.97 μg/g for Mn. The results of the quantitative analysis of porphyrins extracted from the coal minerals showed that Onyeama coal has the highest amount of porphyrins (ca～0.96 μg/g) while Okpara has the lowest (ca～0.30 μg/g). The porphyrins were qualitatively characterized by a combination of thin layer chromatography (TLC), infrared, and ultraviolet-visible spectrophotometers. The results of the mid infrared analysis (MIR) showed the presence of absorption bands at 3 440 cm～1～3 450 cm-1 and 1 640 cm-1～1 680 cm-1 , which are owing to the stretching vibrations of N - H and C = C of aromatics, with C- H out of plane (oop) bending vibrations at wavenumbers less than 900 cm-1, all of which are characteristic absorptions of porphyrin free base. The ultraviolet-visible data showed prominent peaks at ～400 nm(Soret band) and at wavelength ranges of 535 nm～550 nm(β-band) and 565 nm～ 600 nm (α-band) for the coal porphyrins analyzed. The geochemical significance of the metals and porphyrins in coal minerals are discussed.     

Slurry-based procedures to determine chromium, nickel and vanadium in complex matrices by ETAAS

Two slurry-based ETAAS methodologies are compared to determine directly Cr, Ni and V in coal fly ash, soils and sediments: current slurry analysis (USS) and ‘slurry extraction’ (SE). Slurries for USS-ETAAS were prepared in 0.5% HNO₃. HF and HNO₃ were evaluated as chemical modifiers. HF was the extractant for the SE-ETAAS approach.A unique slurry-based procedure to measure Cr, Ni and V could not be established. Cr concentrations up to 100 μg g^{− 1} were accurately determined by USS (0.5% HNO₃; λ = 429.0 nm; LOD = 0.35 μg g^{− 1}) whereas higher contents required the SE procedure (sample grinding, 30% HF; LOD = 0.02 μg g^{− 1}). Both methods were appropriate to determine Ni (LOD = 0.11 and 0.08 μg g^{− 1}, for USS and SE, respectively). V was satisfactorily quantified only with the USS approach (LOD = 0.80 μg g^{− 1}).     

Indirect atomic absorption spectrometry (IAAS) as a tool for the determination of iodide in infant formulas by precipitation of AgI and redissolution with cyanide

A method to determine iodide in infant formula samples by indirect atomic absorption spectrometry (IAAS) was developed. The iodide in solution resulting from an alkaline digestion (Na₂CO₃–NaOH) of the sample is precipitated with silver; the precipitate is redissolved by adding cyanide solution, and this solution is subjected to GF-AAS. Temperatures of 1000 and 2100°C were selected for the ashing and atomization steps, respectively, using a mixture of Pd and Mg(NO₃)₂ as a matrix modifier (at concentrations of 36 and 16 μg ml⁻¹, respectively). The sensitivity, LOD, LOQ and characteristic mass obtained were, respectively, 1.12×10⁻² l μg⁻¹, 3.1 μg g⁻¹ and 10.4 μg g⁻¹ and 7.3 pg, referred to sample. The linear interval of concentrations extends up to 10 μg l⁻¹ of iodide, with no need to use the standard addition method; the mean R.S.D. of data within this range is 3.4%, with 2.9% over the whole procedure. No interfering effects were observed among the foreign ions studied, and 100.0% was the mean analytical recovery achieved within the linear range of concentrations. The application of the method to seven real samples gave a mean content of 12.8 μg g⁻¹ of iodide, as well as less than 3.1 μg g⁻¹ in eight other samples.     

Analysis of BTEX, PAHs and metals in the oilfield produced water in the State of Sergipe, Brazil

During oil and gas exploitation, large amounts of produced water are generated. This water has to be analyzed with relation to the chemical composition to deduce the environmental impact of its discharge after a treatment process. Therefore, a study was carried out to evaluate preliminarily the BTEX (benzene, toluene, ethylbenzene and xylenes), polycyclic aromatic hydrocarbons (PAHs) and metals contents in produced water samples taken from effluents of the Bonsucesso treatment plant located in the city of Carmópolis, the most important oil and gas producer in the State of Sergipe, North-east of Brazil. Three methods were optimized to determine the target compounds. Polycyclic aromatic hydrocarbons were determined by gas chromatography with mass spectrometric detection (GC/MS), volatile aromatic hydrocarbons (BTEX) by gas chromatography with photoionization detector (GC/PID) and metals were analyzed by flame atomic absorption spectrometry (FAAS). The results showed that concentrations of the target compounds in these samples ranged from 96.7 to 1397 μg L^− 1 for BTEX, from 0.9 to 10.3 μg L^− 1 for PAHs and from 0.003 to 4540 mg L^− 1 for metals.     

Chitosan–magnetite nanocomposites (CMNs) as magnetic carrier particles for removal of Fe(III) from aqueous solutions

This research focuses on removal of Fe(III) from aqueous solution using chitosan–magnetite nanocomposites as potential sorbent. The presence of nanosized magnetic particles within the nanocomposites was confirmed by TEM and SAED analysis. The particles with diameter 508 μm and 84 μm, follow Frendlich sorption isotherm at 30 °C, and the Frendlich constants (K_F, 1/n) have been found to be 5.974 mg g⁻¹, 2.66 and 35.98 mg g⁻¹, 1.385, respectively. Out of various kinetic models, the experimental data for dynamic uptake of Fe(III) is best fitted on ‘pseudo-second order’ kinetic model. The linear nature of plots between log (% sorption) and log (time) is indicative of intra-particle diffusion. For the particles with diameters 508 μm and 84 μm, the value of k_id was found to be 1.78 mg l⁻¹ min^−0.5 and 2.13 mg l⁻¹ min^−0.5. The sorption mean free energy from the Dubinin–Radushkevic isotherm was found to be 7.04 kJ mol⁻¹ indicating chemical nature of sorption. The increase in chitosan content in sorbent particles is found to enhance the Fe(III) uptake. The various thermodynamic parameters have also been evaluated. Finally, the presence of Cu²⁺ ions in the sorbate is found to decrease the uptake of Fe(III).     

Determination of manganese and zinc in powdered chocolate samples by slurry sampling using sequential multi-element flame atomic absorption spectrometry

In the present work, a slurry sampling flame atomic absorption spectrometric method to determine directly manganese and zinc in powdered chocolate samples is proposed. The optimization step was performed using univariate methodology involving the following factors: nature and concentration of the acid solution, sonication time, and particle size. The established conditions led to the use of a sample mass of 150 mg, 2.0 mol L^− 1 nitric acid solution, sonication time of 15 min, and a slurry volume of 50 mL. This method allows the determination of manganese and zinc with detection limit of 52 and 61 ng g^− 1, respectively, and a precision expressed as relative standard deviation (RSD) of 2.6% and 3.2% (both, n = 10) for contents of manganese and zinc of 52.4 and 100.0 μg g^− 1, respectively. The proposed method was applied for determination of manganese and zinc in five powdered chocolate samples. In these, the manganese content varied from 42.8 to 52.7 and from 88.6 to 102.4 μg g^− 1 of zinc. The analytical results were compared with the results obtained by analysis of these samples after digestion using open vessel and acid bomb digestion procedures and determination using FS-FAAS. The statistical comparison by t-test (95% confidence level) showed no significant difference between these results.     

Levels of cadmium and lead in blood: an application of validated methods in a group of patients with endocrine/metabolic disorders from the Rome area

Lead (Pb) and cadmium (Cd) are environmental pollutants, known to cause adverse health effects in humans even following long-term exposure to low doses. These metals, individually or in combination with other persistent environmental contaminants, have been claimed to have the potential to cause alterations in the function of the endocrine system. Human exposure to Pb and Cd is generally assessed by monitoring their concentrations in blood, taking into account the influence of various factors, such as age, gender, smoking habit, occupation, alcohol consumption, diet and air pollution. Following the phase-out of leaded gasoline in the European Union and improvements in food-packaging and contamination control, a decrease in blood Pb levels of the general population has been observed in several European countries and the USA. We report the preliminary results of a study, performed within the framework of the project “Human Exposure to Xenobiotics with potential Endocrine Activities: Evaluation of Reproductive and Developmental risks”. We measured the concentrations of Cd and Pb in the blood of a group of patients with endocrine/metabolic disorders. The analytical procedures, based on atomic absorption spectrometry, were validated according to the EURACHEM guidelines. The median values and ranges were 0.48 μg l⁻¹ (0.20–1.73 μg l⁻¹) and 21.8 μg l⁻¹ (12.0–65.7 μg l⁻¹) for Cd and Pb, respectively; the Cd levels were significantly higher in smokers. Overall, the concentrations of Cd and Pb found in our series of patients were comparable to levels currently expected in the general population.     

Spectrophotometric determination of zinc, cadmium, and lead after extraction of their morpholine-4-carbodithioates into molten naphthalene and replacement by copper

Zinc, cadmium, and lead react quantitatively in the pH ranges of 3.9–9.2, 3.5–11.2, and 5.5–10.5, respectively, to form water insoluble and thermally stable complexes which are easily extracted into molten naphthalene. The solid naphthalene containing the colorless complex is dissolved in chloroform and then replaced by copper to develop a yellow color in the chloroform layer. The absorbance in each case is measured at 435 nm against reagent blank. Beer's law holds over the concentration ranges of 3.5–95.0, 3.0–105.0, and 8.5–125. 0 μg for zinc, cadmium, and lead, respectively, into 10 ml of the chloroform solution. The molar absorptivities are calculated to be Zn, 1.048 × 10⁴ liters mol⁻¹ cm⁻¹; Cd, 1.054 × 10⁴ liters mol⁻¹ cm⁻¹, and Pb, 1.014 × 10⁴ liters mol⁻¹ cm⁻¹ with sensitivities in terms of Sandell's definition of 0.0062 μg Zn/cm², 0.010 μg Cd/cm², and 0.020 μg Pb/cm², respectively. Ten replicate determinations of sample solutions containing 30 μg of zinc, 18.7 μg of cadmium, and 42.5 μg of lead give mean absorbances 0.480, 0.175, and 0.208 with standard deviations of 0.0017, 0.0013, and 0.0015 or relative standard deviations of 0.35, 0.74, and 0.72%, respectively. The interference of various ions has been studied and the method has been applied to the determination of cadmium in various synthetic mixtures and zinc and lead in some standard reference materials.     

Heavy metal inputs in Northern Patagonia lakes from short sediment core analysis

Summary Heavy metal profiles of short sediment cores sampled from lakes located in Nahuel Huapi National Park, Northern Patagonia, Argentina, were determined by INAA. Core dating was performed by measuring natural ²¹⁰Pb and anthropogenic ¹³⁷Cs, and by identification of tephra layers. No evidence was found for the input increase of the trace elements Sb, Ba, Cs, Zn, Co, Hf, Ni, Se, Sr, Ti, U, and V in the lake environment. High As concentrations (up to 250 μg ^. g^-1) were found in relation with the diffusion processes of Mn and Fe oxides. Strong correlation was observed between the Br concentration and organic matter content, but no evidence was found for the relevant increase of Br inputs in recent years. Ag concentrations were found to be enriched in the upper core layers over the baseline values determined for deep layers ranging from 0.1 to 0.2 μg ^. g^-1. Hg concentration profiles were also enriched in the upper core layers over the baseline (from less than 0.07 to 0.2 μg ^. g^-1 for pre-industrial time, to 0.1 to 0.3 μg ^. g^-1 for modern times) but in relation with the increased organic matter content of the sediment.     

Determination of metals in marine species by microwave digestion and inductively coupled plasma mass spectrometry analysis

A microwave digestion method suitable for determination of multiple elements in marine species was developed, with the use of cold vapor atomic spectrometry for the detection of Hg, and inductively coupled plasma mass spectrometry for all of the other elements. An optimized reagent mixture composed of 2 ml of HNO₃, 2 ml of H₂O₂ and 0.3 ml of HF used in microwave digestion of about 0.15 g (dry weight) of sample was found to give the best overall recoveries of metals in two standard reference materials. In the oyster tissue standard reference material (SRM 1566b), recoveries of Na, Al, K, V, Co, Zn, Se, Sr, Ag, Cd, Ni, and Pb were between 90% and 110%; Mg, Mn, Fe, Cu, As, and Ba recoveries were between 85% and 90%; Hg recovery was 81%; and Ca recovery was 64%. In a dogfish certified reference material (DORM-2), the recoveries of Al, Cr, Mn, Se, and Hg were between 90% and 110%; Ni, Cu, Zn, and As recoveries were about 85%; and Fe recovery was 112%. Method detection limits of the elements were established. Metal concentrations in flounder, scup, and blue crab samples collected from coastal locations around Long Island and in the Hudson River estuary were determined.     

A biomonitoring study: 210Po and heavy metals in marine organisms from the Adriatic Sea (Italy)

In various samples of marine organisms from the central Adriatic Sea ²¹⁰Po was determined by alpha spectrometry and thirteen heavy metals (Mn, Fe, Co, Cr, V, Ni, Cu, Zn, Cd, As, Sn, Hg and Pb) by energy dispersive, polarised X ray fluorescence spectrometry (EDPXRF). ²¹⁰Po activity concentration ranged between 0.3 and 44.6 Bq kg⁻¹ fresh weight. The data obtained depend upon the type of the marine organism; among the pelagic species, anchovy displayed the highest polonium concentration. Typical concentration ( \upmu \textg·\textg_(\textfresh) ^{- 1} ) \left( {\upmu {\text{g}}\cdot{\text{g}}_{{({\text{fresh}})}}^{ - 1} } \right) ranges were as follows: Mn: <1.32–1.73; Fe: 4.11–94.27; Co < 0.13–0.23; Ni: <0.13–0.52; Cu: 0.37–145.31; Zn: 0.46–16.46; Cd: <0.10–0.25; As: 0.36–60.52; Hg: <0.13–0.70; Pb: <0.13–0.35, Sn: <0.20–12.67; V and Cr were always <1.32. The data obtained are also compared with those obtained by other authors for the same organism coming from other Italian seas.     

The decomposition of oils and fats in a stream of oxygen for the determination of trace elements

For the determination of Al, Cr, Mn, Fe, Cu, Zn, Se, Cd, Hg and Pb at μg g^-1 and ng g^-1 levels in oils and fats by electrothermal atomic absorption spectrometry (a.a.s.), the sample is burnt in a stream of pure oxygen in a special combustion apparatus (Trace-O-Mat). Volatile elements are condensed on a cold finger cooled with liquid nitrogen. After combustion the trace elements are dissolved off the cooled areas and from the sample holder by refluxing with 2 ml of high-purity nitric acid (65%). Recoveries were tested on reference materials by electrothermal a.a.s. and were found to be ? 95%.     

Use of high resolution continuum source atomic absorption spectrometry as a detector for chemically generated noble and transition metal vapors

Vapor generation and atomization conditions in a heated quartz tube to detect Ag, Cd, Co, Cu, Ni and Zn using High Resolution Continuum Source AAS (HRCSAAS), were optimized. Vapors were generated after mixing acidified solutions containing 8-hydroxiquinoline (oxine) with sodium tetrahydroborate. Afterwards, they were swept to the heated quartz cell by an argon flow.Reaction loop size and temperature of the quartz cell were optimized for each element. A temperature of 960 °C was selected as a compromise value to detect most of the metals. Afterwards, a Plackett–Burmann design was proposed to select which parameters were most important. Type of acid and its concentration were the most statistical significant variables. Optimum conditions for sequential detection of Cd, Cu, Ni and Zn were: 1 mg L^− 1 Co as catalyst, 250 mg L^− 1 oxine, 0.6 M nitric acid, 1.75% (w/w) sodium tetrahydroborate (prepared in 0.4 (w/v)% NaOH), a reaction loop of 250 µL, and a 25 L h^− 1 carrier Ar flow. Ag and Co were each detected in their own optimized conditions. Analytical performance of the system was evaluated in connection with a selected pixel number, and spectral correction was used to eliminate NO absorption bands interference in Zn detection. Detection limits were in the range of 1.5–18 μg L^− 1 for Ag, Cu, Cd and Zn, whereas sensitivity was worst for Co (169 μg L^− 1) and Ni (586 μg L^− 1). Atomization in a quartz cell of Co and Ni volatile species, generated by an addition of sodium tetrahydroborate to an acidified solution of the analytes, was reported for the first time in this paper. Precision expressed as RSD(%) had values lower than 10% except for Ni.     

Determination of zinc and copper in human hair by slurry sampling employing sequential multi-element flame atomic absorption spectrometry

The present work proposes a direct method based on slurry sampling for the determination of zinc and copper in human hair samples by multi-element sequential flame atomic absorption spectrometry. The slurries were prepared by cryogenic grinding and sonication of the samples. The optimization step was performed using univariate methodology and the factors studied were: nature and concentration of the acid solution, amount sample/slurry volume, sonication time, and particle size. The established experimental conditions are the use of a sample mass of 50 mg, 2 mol L^− 1 nitric acid solution, sonication time of 20 min and slurry volume of 10 mL. Adopting the optimized conditions, this method allows the determination of zinc and copper with detection limits of 88.3 and 53.3 ng g^− 1, respectively, and precision expressed as relative standard deviation (RSD) of 1.7% and 1.6% (both, n = 10) for contents of zinc and copper of 100.0 and 33.3 μg g^− 1, respectively. The accuracy was checked and confirmed by analysis of two certified reference materials of human hair. The procedure was applied for the determination of zinc and copper in two human hair samples. The zinc and copper contents varied from 100.0 to 175.6 and from 3.2 to 32.8 μg g^− 1, respectively. These samples were also analyzed after complete digestion in a closed system and determination by FAAS. The statistical comparison by t-test (95% confidence level) showed no significant difference between these results.     

Organically modified silica gel and flame atomic absorption spectrometry: employment for separation and preconcentration of nine trace heavy metals for their determination in natural aqueous systems

A 5-formyl-3-(1′-carboxyphenylazo) salicylic acid-bonded silica gel (FCPASASG) chelating adsorbent was synthesized according to a very simple and rapid one step reaction between aminopropyl silica gel (APSG) and 5-formyl-3-(1′-carboxyphenylazo) salicylic acid (FCPASA) and its adsorption characteristics were studied in details. Nine trace metals viz.: Cd(II), Zn(II), Fe(III), Cu(II), Pb(II), Mn(II), Cr(III), Co(II) and Ni(II) can be quantitatively adsorbed by the adsorbent from natural aqueous systems at pH 7.0–8.0. The adsorbed metal ions can be readily desorbed with 1 M HNO₃ or 0.05 M Na₂EDTA. The distribution coefficient, K_d and the percentage concentration of the investigated metal ions on the adsorbent at equilibrium, C_M,_eqm % (Recovery, R%) were studied as a function of experimental parameters. The logarithmic values of the distribution coefficient, logK_d, are 3.7–6.4. Some foreign ions caused little interference in the preconcentration and determination of the investigated nine metals by flame atomic absorption spectrometry (AAS).The adsorption capacity of FCPASASG was 0.32–0.43 meq g⁻¹. C and N elemental analyses of the adsorbent (FCPASASG) allowed us to calculate a surface converge of 0.82 mmol g⁻¹. This value compares well with the best values reported for the azo compounds. The adsorbent and its formed metal chelates were characterized by IR (absorbance and/or reflectance) and UV spectrometry, potentiometric titrations and thermogravimetric analysis (TGA and DTG). The mode of chelation between the FCPASASG adsorbent and the investigated metal ions is proposed to be due to reaction of those metal ions with the salicylic and/or the carboxyphenylazo chelation centers of the FCPASASG adsorbent. Nanogram concentrations (0.07–0.14 ng ml⁻¹) of Cd(II), Zn(II), Fe(III), Pb(II), Cr(III), Mn(II), Cu(II), Co(II) and Ni(II) can be determined reliably with a preconcentration factor of 100.     

Acid extraction and cloud point preconcentration as sample preparation strategies for cobalt determination in biological materials by thermospray flame furnace atomic absorption spectrometry

A thermospray flame furnace atomic absorption spectrometer (TS-FF-AAS) was employed for Co determination in biological materials. Cobalt presents a high atomization temperature and consequently poor sensitivity is obtained without changing its thermochemical behavior. The effect of different complexing agents on sensitivity was evaluated based on the formation of Co volatile compounds. A cloud point procedure was optimized for Co preconcentration for further improvement of sensitivity. Samples were treated with 1 mol l^− 1 hydrochloric acid solution for quantitative extraction of Co without simultaneous extraction of Fe, since it is a strong interferent. After the extraction and preconcentration steps, a sample volume of 150 μl was introduced into the hot Ni tube using air as carrier at a flow-rate of 0.4 ml min^− 1. The best sensitivity was attained using ammonium pyrrolidinedithiocarbamate (APDC) and Triton X-114 was employed for implementation of the cloud point procedure. The detection limit obtained for Co was 2.1 μg l^− 1 and the standard deviation was 5.8% for a solution containing 100 μg l^− 1 (n = 10). Accuracy was checked using two certified reference materials (tomato leaves and bovine liver) and results were in agreement with certified values at a 95% confidence level. Employing the developed procedure, Co were quantified in different biological materials (plant and animal tissues). The proposed method presents suitable sensitivity for cobalt determination in the quality control of foods.     

Speciation analysis of selenium enriched green onions (Allium fistulosum) by HPLC-ICP-MS

Green onions (Allium fistulosum) enriched with 10 or 100 μg mL^− 1 Se(IV) or SeMet were analyzed for total selenium and species distribution. Anion and cation exchange chromatographies were applied for the separation of selenium species with mass spectrometric detection. Two different sample preparation methods (NaOH and enzymatic) were compared from the Se extraction efficiency point of view. Total selenium concentration accumulated by the onions reached the 200 μg g^− 1 level expressed for dry weight when applying SeMet at a concentration of 100 μg mL^− 1 as the source of Se. Speciation studies revealed that both in onion bulbs and leaves the predominant form of organic selenium is Se-methyl-selenocysteine (MeSeCys). When Se(IV) was applied for Se-enrichment at a concentration level of 100 μg mL^− 1 both onion leaf and bulb contained a significant amount of inorganic selenium. An unknown compound was also detected.     

A Catalytic Method for Determining Cadmium(II), Nickel(II), and Zinc(II) Inhibitor Metals

The inhibitory effect of Cd(II), Ni(II), and Zn(II) on the oxidation of 3,3′,5,5′ -tetramethylbenzidine with periodate was detected. The optimum reaction conditions were found, and the procedures were developed for determining 1 × 10⁻² to 10 μg/mL Cd(II), Ni(II), and Zn(II) in solution. The indicator reaction was performed on a number of supports. The maximum inhibitory effect was observed on silica gel-based plates for TLC. Procedures for determining 6 × 10⁻³ to 0.4 μg of these metals were developed. Silica gel plates with the immobilized reagent for cadmium (bromobenzothiazo) were used to preconcentrate cadmium. A selective test procedure was developed for determining 1 × 10⁻⁴ −3 × 10⁻³ μg/mL cadmium with the visual detection of the process rate. Upon the introduction of dimethylglyoxime into the indicator reaction, the inhibitory effect of nickel changed to its promoting effect and the detection limit for nickel was lowered. A procedure was developed for determining 3 × 10⁻⁴ −3 × 10⁻³ μg/mL nickel in solution and 7 × 10⁻³−4 × 10⁻¹ μg nickel on the surface of Sorbfil plates. An assumption was made about the reasons for the inhibitory effect of metal ions on the oxidation of aryl diamines with periodate.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 6, 2005, pp. 662–669.Original Russian Text Copyright © 2005 by Beklemishev, Kiryushchenkov, Stoyan, Dolmanova.     

Fast sequential multi-element determination of Ca,Mg, K,Cu, Fe,Mn and Zn for foliar diagnosis using high-resolution continuum source flame atomic absorption spectrometry: Feasibility of secondary lines,side pixel registration and least-squares background correction

The fast sequential multi-element determination of Ca, Mg, K, Cu, Fe, Mn and Zn in plant tissues by high-resolution continuum source flame atomic absorption spectrometry is proposed. For this, the main lines for Cu (324.754 nm), Fe (248.327 nm), Mn (279.482 nm) and Zn (213.857 nm) were selected, and the secondary lines for Ca (239.856 nm), Mg (202.582 nm) and K (404.414 nm) were evaluated. The side pixel registration approach was studied to reduce sensitivity and extend the linear working range for Mg by measuring at wings (202.576 nm; 202.577 nm; 202.578 nm; 202.580 nm; 202.585 nm; 202.586 nm; 202.587 nm; 202.588 nm) of the secondary line. The interference caused by NO bands on Zn at 213.857 nm was removed using the least-squares background correction. Using the main lines for Cu, Fe, Mn and Zn, secondary lines for Ca and K, and line wing at 202.588 nm for Mg, and 5 mL min^− 1 sample flow-rate, calibration curves in the 0.1–0.5 mg L^− 1 Cu, 0.5–4.0 mg L^− 1 Fe, 0.5–4.0 mg L^− 1 Mn, 0.2–1.0 mg L^− 1 Zn, 10.0–100.0 mg L^− 1 Ca, 5.0–40.0 mg L^− 1 Mg and 50.0–250.0 mg L^− 1 K ranges were consistently obtained. Accuracy and precision were evaluated after analysis of five plant standard reference materials. Results were in agreement at a 95% confidence level (paired t-test) with certified values. The proposed method was applied to digests of sugar-cane leaves and results were close to those obtained by line-source flame atomic absorption spectrometry. Recoveries of Ca, Mg, K, Cu, Fe, Mn and Zn in the 89–103%, 84–107%, 87–103%, 85–105%, 92–106%, 91–114%, 96–114% intervals, respectively, were obtained. The limits of detection were 0.6 mg L^− 1 Ca, 0.4 mg L^− 1 Mg, 0.4 mg L^− 1 K, 7.7 µg L^− 1 Cu, 7.7 µg L^− 1 Fe, 1.5 µg L^− 1 Mn and 5.9 µg L^− 1 Zn.