High-resolution Continuum Source Flame Research Articles

Fast sequential multi element analysis of lead and cadmium in canned food samples using effervescent tablet-assisted switchable solvent based liquid phase microextraction (EA-SS-LPME) coupled with high-resolution continuum source flame atomic absorption spectrometry (HR-CS-FAAS)

An effervescent tablet-assisted switchable solvent based liquid phase microextraction (EA-SS-LPME) was developed for multi-element determination of Pb and Cd in various samples using high-resolution continuum source flame atomic absorption spectrometry (HR-CS-FAAS). The effervescent tablets were used for improving the extraction efficiency. Triethylamine as a hydrophobic solvent was switched to protonated triethylamine carbonate by CO2 and used to extract dithizone complexes from samples. Calibration linearities were obtained from 0.06 to 10.0 mg L−1 (Pb) and 0.02 to 1.50 mg L−1 (Cd). LODs of the proposed method were 0.0195 (Pb) and 0.0068 (Cd). LOQs were 0.0649 mg L−1 (Pb) and 0.0228 mg L−1 (Cd) with %RSDs of 1.25%–1.69% (Pb) and 1.07%–1.64% (Cd). The proposed method was applied for the determination of Pb and Cd in water and canned food samples. The spiked recoveries were 82.3–119.0% (Pb) and 81.7–120.0% (Cd). In addition, the PF was 3.3, with EF at 1.4 (Pb) and 2.6 (Cd) obtained after extraction for under 8 min.

Calcium monofluoride as a target molecule for determination of organic fluorine in gasoline and its components using high-resolution continuum source flame molecular absorption spectrometry

High-resolution continuum source molecular absorption spectrometry (HR-CS MAS) is widely applied to determine fluorine in various materials, and its graphite furnace option with calcium monofluoride as a target molecule is popular. However, up to now, the idea of using the molecule in flame molecular absorption spectrometry seemed impossible or impractical due to the expected low sensitivity and detectability. The following paper completely changes this view. The CaF molecule has been proven to be an excellent tool for determining organic fluorine in gasoline using flame molecular absorption spectrometry, giving benefits over previously used gallium monofluoride. The following favourable circumstances decide about it: 1) relatively high population of CaF molecules in preferable air-acetylene flame, 2) possibility of using oil calcium “standard” as a source of calcium, which is well dissoluble in both xylene (solvent) and gasoline, 3) extremely good stability of baseline in the used spectrum range, 4) relatively high freedom from spectral and chemical interferences and 5) possibility of summing of many pixels response. The analysis relies on simple sample dilution in xylene, with the addition of oil calcium “standard” to obtain 1500 mg L−1 Ca in measured solutions. Simplified standard addition calibration is used to overcome the effect of variability of samples (various physical properties and combustion characteristics). The signals of four CaF rotational “lines” are summed. The only undesirable spectral effect is a molecular absorption at the second “line” (606.0368 nm), which is attributed to the absorption by the CaOH molecule formed in the flame. The effect can be easily overcome by using the least square background correction, LSBC. The characteristic concentration and the detection limit for solutions are 6 and 0.6 mg L−1, respectively. The detection limit recalculated for the original sample is 2 mg kg−1 in the case of alkalyte, reformate and gasoline, while it is 6 mg kg−1 in the case of volatile isomerizate, mainly due to necessary higher sample dilution. The calibration curve is linear over at least two orders of magnitude. Heptafluorobutanol has been found a suitable standard. The agreement of the results of the proposed method and standard combustion ion chromatography is satisfactory.

Determination of Cadmium in Water Samples by Automated Flow-Batch Cloud Point Extraction (CPE) Hyphenated to High-Resolution Continuum Source Flame Atomic Spectrometry (HR-CS FAAS)

A computer-controlled multicommuted flow-batch system is reported that allows for the online cloud point extraction of metal ions followed by high-resolution continuum source flame atomic absorption spectrometric (HR-CS GFAAS) detection. This approach combines reduced sample and reagent consumption and a short analysis time with the increased precision and sensitivity characteristic of flow-batch analysis and modern extraction techniques. As proof of concept, cadmium in aqueous solutions was determined by the formation of a hydrophobic complex [Cd(PAN)2]. Parameters related to complex formation (pH, pyridyl-azo-naphthol-PAN concentration, complexation time), cloud point extraction (Triton X-114 concentration, electrolyte composition, rich phase trapping), and the multicommuted flow-batch system (flow rates, timing control) were optimized. A small column packed with hydrophobic cotton was used as the interface between the extraction and detection stages to stack the cadmium-containing rich phase in a short plug. Optimized parameters led to a 5.0 to 75.0 µg L−1 linear range, 1.3 µg L−1 limit of detection, 4.3 µg L−1 limit of quantification and 1.8% coefficient of variation (n = 12). Accuracy was evaluated by analyzing a certified reference material EP-H (drinking water) and by recovery tests employing tap water, groundwater, mineral water, and reuse water samples.

Method development for determination of organic fluorine in gasoline and its components using high-resolution continuum source flame molecular absorption spectrometry with gallium fluoride as a target molecule

High-resolution continuum source molecular absorption spectrometry (HR-CS MAS) has been developing fast for fluorine determination, but neither flame nor graphite furnace technique have ever been applied for the analysis of petroleum or its products. Hydrogen fluoride can be applied in technologies of gasoline components production, unfortunately, arising organic fluorides can contaminate final product. The aim of this work was development of fast and simple HR-CS MAS method, with an ordinary air-acetylene flame, for determination of organic F in gasoline and its components. Gallium fluoride as a target molecule was the imposing choice, because Ga undergoes atomization at relatively low temperature, and the GaF molecule is known to provide good sensitivity in F determination. Severe difficulties have arisen to get higher concentration of gallium (as Ga(III)acetylacetonate) in the measured (xylene) solution. Furthermore, depending on the flame character, the spectrum of the GaF molecule at the most sensitive 211.248 nm rotational “line”could have been disturbed by intensive noise (a case of too rich flame) or overlapped by the OH molecule spectrum (a case of too lean flame). The effects, as well as sensitivity of F determination, depended on the sample volatility and its dilution ratio. The difficulties have been overcome by adjusting the solution aspiration rate and the additional air flow rate to get not-disturbed baseline. The least square background correction (LSBC) with the OH molecule spectrum as the correction spectrum (the OH molecule spectrum intentionally generated for the first time) and the standard addition calibration have been also applied. Huge difference in sensitivity, up to one order of magnitude, depending on the F compound volatility and its chemical character was stated. A standard giving the best sensitivity (heptafluorobutanol) turned out to be the most suitable for calibration in analysis of real samples (satisfactory agreement with results of combustion ion chromatography). It was found that HF introduced into the solution of the investigated sample does not contribute to the increase of F signal. Using 5000 mg L−1 of Ga in a solution, the best characteristic concentration and detection limit are 3.2 mg L−1 and 0.93 mg L−1, respectively. The developed method enabled to identify high contamination of some gasoline components with organic F species, which constituted significant corrosion and environmental threat.

Multi-Element Determination of Trace Elements in B7-diesel Oil by High-Resolution Continuum Source Flame Atomic Absorption Spectrometry

In this work, a method for sequential multi-element determination of Cu, Fe, Ni, Pb, Zn, Al, Cr and Sn in B7-diesel oil samples by high-resolution continuum source flame atomic absorption spectrometry (HR-CS F AAS) was proposed. The sample preparation was based on formation of microemulsion (ME), which was investigated through a three-phase diagram. The ME composition adopted was B7-diesel oil (3.3 g), aqueous phase containing nitric acid (1.4 mol L-1, 300 μL) and n-propanol (up to 10 mL). The use of surfactant Triton X-100 in the formation of ME was also evaluated. Limits of detection in the range of 0.01 – 0.4 mg kg-1 were obtained. Spike-recovery tests were accomplished and the results varied between 93 and 124%. The accuracy of the proposed method was confirmed by the analysis of certified reference material (CRM) NIST SRM 1084a (Wear-Metals in Lubricating Oil); there was no statistical difference between the obtained results and the certified values (at 95% confidence level). Twelve B7-diesel oil samples were analyzed and Cu, Fe and Cr were found in three samples. The proposed method was simple, fast and accurate. The sequential multi-element determination of trace elements presented advantages as low costs and reduction in analysis time, being appropriate for routine analysis.

Method for organic fluorine determination in gasoline and its components using high-resolution continuum source flame molecular absorption spectrometry with gallium fluoride as a target molecule

Organic fluorides can arise due to the usage of HF in technologies of gasoline production, therefore, it is necessary to identify contamination of gasoline or its components with organic fluorine. For this aim, simple and fast method is proposed. The method relies on sample dilution in xylene, followed by the solution aspiration to a high-resolution continuous source spectrometer for measurement of absorption of radiation by GaF molecule, arisen in air-acetylene flame. Gallium(III) acetylacetonate is carefully dissolved and introduced to all measured solutions at Ga concentration 5000 mg L−1. For standard addition calibration three types of samples solutions are prepared to contain: none, 50 mg L−1 and 100 mg L−1 of added fluorine. As fluorine standard 2, 2, 3, 3, 4, 4, 4-heptafluoro-1-pentanol is applied. The lowest possible flow rate of acetylene is recommended. The solution flow rate and the additional air flow rate should be adjusted to obtain not-disturbed baseline. The overlap of the GaF signal with residual signal of the OH molecule can be overcome using least square background correction. Five pixels are recommended for signal evaluation at the most sensitive 211.248 nm rotational “line”. Using such conditions characteristic concentration was 3.2 mg L−1. Detection limit recalculated for initial sample was 4-10 mg L−1.•High-resolution continuum source flame molecular absorption spectrometry turned out to be an excellent tool for determination of pollution of gasoline with organic fluorine.•Due to application of GaF as a target molecule, it is possible to use a low-temperature and easy for operation air-acetylene flame.•The proposed method can be applied for analysis of alkylate, reformate, isomerizate, ethanol as well as commercial automotive and aviation gasoline.

Simultaneous determination of Fe and Zn in dried blood spot by HR-CS GF AAS using solid sampling

Dried Blood Spot (DBS) was evaluated as a solid sampling (SS) strategy for the simultaneous determination of Fe and Zn in blood samples by Solid Sampling High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry (SS HR-CS GF AAS). The alternative lines of Fe and Zn at 307.572 and 307.589 nm, respectively, were evaluated. A good correlation between the area of DBS (in mm2) and volume of blood (in µL) was observed up to 200 µL of blood. A 3.4 mm diameter paper disk, equivalent 3.86 ± 0.13 µL, was punched from the DBS and employed for blood analysis. Random sampling through the area of the paper circle produced by 50 μL blood samples showed no chromatographic effects. The upside of the solid sampling 'boat type' graphite platform was coated with a W-based film. This coating allowed around 350 firings. The use of 3 µL of 15% v/v H2O2 solution as chemical modifier improved both the thermal stability and peak profile of Zn for aqueous medium (standard solution deposited onto Whatman paper), possibly because of the weakening of Zn-paper interactions or even by the formation of thermally more stable Zn oxides. Solid standards used for calibration in the 0.1–3.0 µg Fe and 5.0–50.0 ng Zn ranges were prepared with Whatman 903® paper discs impregnated with standard solutions of the analytes. Results for Fe and Zn determined by the proposed SS HR-CS GF AAS method were in agreement at a 95% confidence level (paired t-test) with those obtained by the comparative method (except for one sample) based on microwave-assisted acid digestion of blood and High-Resolution Continuum Source Flame Atomic Absorption Spectrometry (HR-CS F AAS). The limits of quantification were 10.2 mg/L (0.04 µg) for Fe and 1.2 mg/L (4.6 ng) for Zn. The relative standard deviation was < 10% (n = 12) for a sample containing 516 mg/L Fe and 8.7 mg/L Zn, and the sample throughput was equivalent to ca. 90 s per measurement.

Development of New Canned Chub Mackerel Products Incorporating Edible Seaweeds-Influence on the Minerals and Trace Elements Composition.

This study aimed to develop new canned chub mackerel products incorporating edible seaweeds (Ascophyllum nodosum, Fucus spiralis, Saccorhiza polyschides, Chondrus crispus, Porphyra sp. and Ulva sp.) harvested in the Portuguese North-Central coast, with simultaneous sensory improvement and minerals enrichment. Two processes were compared, namely the addition of seaweeds in i) the canning step and ii) in the brining step (as the replacement for salt). The concentrations of four macrominerals (Na, K, Ca and Mg), chloride, and twelve trace elements (Co, Cu, Fe, I, Li, Mn, Mo, Rb, Se, Sr, V and Zn) were determined by high-resolution continuum source flame atomic absorption spectrometry (HR-CS-FAAS) and inductively coupled plasma mass spectrometry (ICP-MS), respectively. Results showed that canned chub mackerel incorporating C. crispus and F. spiralis was found to be the preferred sensory option, also exhibiting contents enriched with Cl, Co, Cu, Fe, I, Li, Mg, Mn, Mo, Na, Rb, Se, and Sr. This effect was more pronounced when both seaweed species were added to replace the salt added in the brining step.

SEQUENTIAL MULTI-ELEMENT DETERMINATION OF TRACE-METALS IN BIODIESEL SAMPLES USING HR-CS FAAS

In this work the feasibility of sequential multi-element determination of Zn, Fe, Mg, Cu, Na, K, Cr, Al and Ca in biodiesel samples by high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS) was investigated. Biodiesel samples obtained from different sources and different chemical processes were analysed. The samples were diluted with n-propanol and water (1.4 mol L-1 HNO3) to form a microemulsion (ME) before its introduction in the HR-CS FAAS using a flow injection mode. The sample B-01 (obtained from soybean oil) was used for optimisation of the instrumental parameters. The accuracy of the proposed method was checked by analysis of certified reference material (CRM) Conostan BDM2A (for K and Na) and BDM2B (for Ca and Mg) and by comparison with acid digestion and recovery tests (for Zn, Fe, Cu, Cr and Al). The obtained results for CRM analysis showed good agreement with certified values within 95% of confidence (Student’s t-test). Recovery tests values ranged from 87-114%. The method developed for the analysis of biodiesel samples is accurate, simple, fast, and suitable for routine application.

Determination of Rare Earth Elements in Natural Water Samples by Rapid Sequential High-Resolution Continuum Source Flame Atomic Absorption Spectrometry (HR CS FAAS) and inductively Coupled Plasma-Mass Spectrometry (ICP-MS)

A method was developed to sequentially assay ten rare earth elements by high-resolution continuum source flame atomic absorption spectrometry. The rare earth elements Nd, Sm, Eu, Tb, Ho, Er, Tm, Yb, Y, and Sc were assayed in environmental water samples which were also analyzed by a reference inductively coupled plasma-mass spectrometry protocol. The samples did not require pretreatment or preconcentration. Interferences for the method were evaluated. Experimental parameters, including the flame composition, burner height, ionization buffers and number of pixels, were optimized. The volume necessary to run measurements in triplicate was only 15 mL per sample. The accuracy, precision and linear range were evaluated. The limits of detection ranged from 0.003 to 0.473 µg mL−1 for the most sensitive (Yb) to the least sensitive (Tb) element.

Fast Sequential Determination of Zn, Fe, Mg, Ca, Na, and K in Infant Formulas by High-Resolution Continuum Source Flame Atomic Absorption Spectrometry Using Ultrasound-Assisted Extraction

In this work, an analytical procedure based on ultrasound-assisted extraction (UAE) was developed for the fast sequential determination of six elements (Zn, Fe, Mg, Ca, Na, and K) in infant formulas using high-resolution continuum source flame atomic absorption spectrometry (HR-CS F AAS). The analytes extraction was performed using HNO3 2.1 mol L−1 and 10 min of sonication time at 80 °C. The limits of detection obtained were 12, 13, 0.48, 96, 137, and 14 mg kg−1 for Zn, Fe, Mg, Ca, Na, and K, respectively. The analysis of a certified reference material of non-fat milk powder (SRM 1549) and infant formula samples after microwave digestion confirmed the trueness of the developed method. Thus, the UAE procedure was employed in order to determine these six elements and their concentration in six infant formulas and their content (in mg kg−1) ranged between 64 and 431 for Zn, 64–370 for Fe, 420–2421 for Mg, 1145–8547 for Na, 750–14,491 for K, and 2827–11,340 for Ca.

Acquiring Information on the Total Content and Speciation of Silicon in Petroleum Products/Fuels Using High-Resolution Continuum Source Flame Atomic Absorption Spectrometry and Wavelength-Dispersive X-ray Fluorescence

Various chemical forms of silicon (Si) possibly present in petroleum products/fuels were investigated in this work: low-molecular-mass species with different compositions, structures, and volatilities, as well as a Conostan oil standard, polysiloxanes, and silicon dioxide. Analysis in xylene solutions was accomplished using wavelength-dispersive X-ray fluorescence (WD XRF) or high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS). Samples were also analyzed using HR-CS FAAS in aqueous solutions after mineralization in a closed microwave-heated system, mineralization in an open system, or mineralization combined with fusion using lithium metaborate. It was found that none of the applied procedures was suitable for the accurate determination of Si in all the tested forms. The total content of Si can only be determined if various methodological variants are applied. Using WD XRF, similar signals are obtained for all the investigated organic Si forms. The procedure is also helpful ...

Molecular interactions and physico-chemical characterization of quercetin-loaded magnetoliposomes.

The bioflavonoid quercetin may prevent magnetoliposomes oxidation, preserving their stability. In this work, the interaction between quercetin and asolectin-based magnetoliposomes was investigated by monitoring the hydration degree, vibrational, rotational and translational mobility parameters of the system as well as its thermodynamic properties. The efficiency of the encapsulation of maghemite magnetic nanoparticles was detected by high resolution-continuum source flame atomic absorption spectrometry (HR-CS FAAS). The magnetic behavior of the system was studied by vibrating sample magnetometry (VSM) technique. The size and surface charge of magnetoliposomes were detected by dynamic light scattering (DLS) and zeta potential (ζ-potential) measurements. The influence of quercetin on the physico-chemical parameters of the magnetoliposomes was evaluated by Fourier transform infrared spectroscopy (FTIR), 31P and 1H nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC) techniques. In vitro antioxidant and antitumoral assays were also performed for the magnetoliposomes. An insertion of quercetin into magnetoliposomes reduced the efficiency of the encapsulation of maghemite nanoparticles by 11%, suggesting a significant interaction between flavonoid and nanoparticles in a specific region of the system. Quercetin discreetly decreased the saturation magnetization of magnetoliposomes, but did not affect the superparamagnetic behavior of the system. 31P and 1H NMR results showed that quercetin did not alter the inverted hexagonal system phase state but decreased lipid polar head mobility. The flavonoid also seems to reorient the choline group above the bilayer phosphate membrane plane, as indicated by ζ-potential system values. FTIR, NMR and DSC responses showed that quercetin disordered the carbonyl and the methylene regions of the magnetoliposomes. Quercetin, as the nanoparticles, seems to be located in the polar head regions of magnetoliposomes, ordering it and diminishing the lipid intermolecular communication in the membrane carbonyl and non-polar regions. The lipid peroxidation of the magnetoliposomes was prevented 8-fold by the presence of quercetin in the system. Also, the flavonoid was responsible for a 45% reduction in the viability of glioma cells. Location and interactions between quercetin and magnetoliposomes components were discussed in order to be correlated with the results of biological activity, contributing to the design of more stable and efficient magnetoliposomes to be applied as contrast and antitumoral agents.

Straightforward silicon determination in water-in-oil-in-water emulsions used for silicon supplementations in food by high-resolution continuum source flame atomic absorption spectrometry

Water-in-oil-in-water (W1/O/W2) double emulsions are complex liquid dispersions employed to entrap, protect and control the release of different substances such as minerals in cosmetics, pharmaceuticals, and food. The present paper proposes a simple and fast analytical procedure for silicon determination in double emulsion samples formulated for the supplementation of silicon in different food products. Silicon determination was performed by flame atomic absorption spectrometry (FAAS) at the main analytical line (251.611 nm) using a high-resolution continuum source instrument. The introduction of the sample in the spectrometer in a continuous or discontinuous mode and the influence of double emulsion matrix on silicon absorbance signals were investigated. At the optimized conditions, the double emulsion samples were analysed using silicon standards in ultrapure water for calibration. The limits of detection (LODs) were 0.04 and 0.11 mg L−1 and the upper limits of silicon linear working ranges were up to 23 and 70 mg L−1 for continuous and discontinuous sample introduction modes, respectively. Silicon spiked double emulsion samples were analysed for validation purposes. The good recoveries (within 95–105%) demonstrated the suitability of the proposed method.

Direct determination of copper and zinc in alcoholic and non-alcoholic drinks using high-resolution continuum source flame atomic absorption spectrometry and internal standardization

A simple, rapid, direct and multi-element method based on high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS) was developed to analyse a large variety of beverages with successful results. The use of the internal standard (IS) calibration method was explored to carry out the direct analysis of drinks with different sugar and/or alcohol content using only one calibration curve. The main absorption lines for the analytes (Cu, Zn and Pb) and the possible ISs (Ag, Co, Ni and Bi) were chosen to perform the analysis. In addition, the possibility of introducing the sample in the spectrometer in a continuous or discontinuous mode was investigated. The limits of quantification (LOQs) obtained using Ag as IS and the continuous sample introduction mode were 0.040 mg L−1 for Zn, 0.016 mg L−1 for Cu, and 0.099 mg L−1 for Pb. In addition, the precision, expressed as the relative standard deviation (RSD), was lower than 4% for the three elements. The developed IS method was applied to analyse different commercial beverages: an apple juice, a ready-to-drink beverage containing fruit juices, an isotonic drink, a lemon and lime flavoured soft drink, a beer, a wine, a gin, a whisky, a rum, and an apple liqueur. For comparison, these beverages were also analysed using a conventional external calibration procedure. The Cu concentration was lower than 1.28 mg L−1 and 0.15 mg L−1 in alcoholic and non-alcoholic drinks, respectively, and Zn concentration was lower than 0.37 mg L−1 in alcoholic and 12.3 mg L−1 in non-alcoholic drinks. The Pb concentration in all the analysed samples was below the limit of detection (LOD). The recoveries in the validation studies were within 92–109% for Cu, 93–111% for Zn and 94–110% for Pb.

HR-CS FAAS based method for direct determination of total concentrations of Ca, Fe, Mg and Mn in functional apple beverages and evaluation of contributions of the bioaccessible fraction of these elements by in vitro gastrointestinal digestion and chemical fractionation

Functional apple beverages, including organic apple juices and apple juices with added species, were studied on the content of total concentrations of Ca, Fe, Mg and Mn as well as bioaccessibility of these elements and their chemical fractionation patterns. A new simplified sample preparation procedure was developed and validated for determination of Ca, Fe, Mg and Mn by high resolution-continuum source flame atomic absorption spectrometry (HR-CS FAAS). Bioaccessibility of Ca, Fe, Mg and Mn from analyzed apple beverages was assessed using in vitro simulated gastrointestinal digestion while chemical partitioning of elements species was carried out with the aid of tandem-column solid phase extraction (SPE). It was established that Ca, Mg and Mn are highly bioaccessible from functional apple beverages (>94% of total concentrations), significantly contributing to recommended daily intakes (RDIs) of these elements, i.e. up to 11%, 19% and 21% per 1 L, respectively, for Ca, Mg and Mn.

Determinations of phosphorus in fertilizers by spark discharge-assisted laser-induced breakdown spectroscopy

A spark discharge system was coupled to laser-induced breakdown spectroscopy (SD-LIBS) to improve sensitivity in the determination of P in fertilizers. A LIBS system consisting of a Q-switched Nd:YAG laser operating at 1064nm and emitting pulses at 50mJ with a fluence of 70Jcm−2 at the focal point was used. Results of preliminary experiments suggested that the most appropriate wavelength to measure P was the P (I) line at 214.9nm, which did not show interferences by Fe, Cu and Zn. The electrical discharge was provided by a homemade high-voltage electronic circuit consisting of two cylindrical tungsten electrodes at the optimized output voltage of 4.5kV, with tips arranged at the optimal distances of 4mm between them and 2mm above the sample surface. To minimize the expected matrix effects calibration standards of P2O5 in the range of 4.8 and 33.3% were prepared by mixing various amounts of a phosphate rock reference material (SRM-120c) with a mixture of CaCO3, CaSO4, (NH2)2CO and KCl at a 1:1:1:1 mass ratio. The calibration curves obtained at a 4.5kV SD-LIBS output voltage showed correlation coefficients ≥0.993, RSD ≤8% and LOQ 5.3% (m/m) P2O5. Data obtained by analyzing commercial samples by the proposed system were in good agreement, at 95% confidence level, with those obtained by using high-resolution continuum-source flame atomic absorption spectroscopy.

Sediment matrix characterization as a tool for evaluating the environmental impact of heavy metals in metal mining, smelting, and ore processing areas

In this work, the matrix characterization (mineralogy, total and local chemical composition, and total organic (TOC) and inorganic carbon (TIC) contents) of different types of sediments from mining- and metallurgy-influenced areas and the assessment of the impact of the matrix on the association of potentially hazardous metals with the mineral phases of these samples, which affect their mobility in the environment, are presented. For these purposes, sediment samples with different origins and from different locations in the environment were analyzed. Anthropogenic sediments from metal-rich post-flotation tailings (Lintich, Slovakia) represent waste from ore processing, natural river sediments from the Hornád River (Košice, Slovakia) represent areas influenced predominantly by the metallurgical industry, and lake sediments from a water reservoir Ružín (inflow from the Hornád and Hnilec Rivers, Slovakia) represent the impact of the metallurgical and/or mining industries. The total metal contents were determined by X-ray fluorescence (XRF) analysis, the local chemical and morphological microanalysis by scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), and the TOC and TIC contents by infrared (IR) spectrometry. The mobility/bioavailability of Cu, Pb, and Zn in/from sediments at the studied areas was assessed by ethylenediaminetetraacetic acid (EDTA) and acetic acid (AA) extraction and is discussed in the context of the matrix composition. The contents of selected potentially hazardous elements in the extracts were determined by the high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS).

Extraction method based on emulsion breaking for the determination of Cu, Fe and Pb in Brazilian automotive gasoline samples by high-resolution continuum source flame atomic absorption spectrometry

This work reports a new method for extraction of Cu, Fe and Pb from Brazilian automotive gasoline and their determination by high-resolution continuous source flame atomic absorption spectrometry (HR-CS FAAS). The method was based on the formation of water-in-oil emulsion by mixing 2.0mL of extraction solution constituted by 12% (w/v) Triton X-100 and 5% (v/v) HNO3 with 10mL of sample. After heating at 90°C for 10min, two well-defined phases were formed. The bottom phase (approximately 3.5mL), composed of acidified water and part of the ethanol originally present in the gasoline sample, containing the extracted analytes was analyzed. The surfactant and HNO3 concentrations and the heating temperature employed in the process were optimized by Doehlert design, using a Brazilian gasoline sample spiked with Cu, Fe and Pb (organometallic compounds). The efficiency of extraction was investigated and it ranged from 80 to 89%. The calibration was accomplished by using matrix matching method. For this, the standards were obtained performing the same extraction procedure used for the sample, using emulsions obtained with a gasoline sample free of analytes and the addition of inorganic standards. Limits of detection obtained were 3.0, 5.0 and 14.0μgL−1 for Cu, Fe and Pb, respectively. These limits were estimated for the original sample taking into account the preconcentration factor obtained. The accuracy of the proposed method was assured by recovery tests spiking the samples with organometallic standards and the obtained values ranged from 98 to 105%. Ten gasoline samples were analyzed and Fe was found in four samples (0.04–0.35mgL−1) while Cu (0.28mgL−1) and Pb (0.60mgL−1) was found in just one sample.

Graphene oxide modified expanded perlite as a new sorbent for Cu(II) and Pb(II) prior to determination by high-resolution continuum source flame atomic absorption spectrometry

ABSTRACTGraphene oxide (GO) modified expanded perlite (EP) was prepared as a new sorbent for solid phase extraction of Cu(II) and Pb(II) prior to determination by high-resolution continuum source flame atomic absorption spectrometry (HR-CS-FAAS). Characterization of the synthesized sorbent was proved by Fourier transform infrared spectroscopy (FT-IR); X-ray diffraction (XRD); Brunaer, Emmet, and Teller (BET); specific surface area; and scanning electron microscopy (SEM) techniques. Several parameters such as pH, eluent type and concentration, flow rate, sample volume, interfering ions, adsorption capacity of sorbent were investigated and optimized. The proposed method was successfully applied for spiked analysis of Cu(II) and Pb(II) ions in tap water and fruity sodas sample, and fine recoveries (relative error <10%) were obtained.