Continuum Source Flame Atomic Absorption 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.

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.

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.

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 ...

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.

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.

Application of high-resolution continuum source flame atomic absorption spectrometry to reveal, evaluate and overcome certain spectral effects in Pb determination of unleaded gasoline

High-resolution continuum source and line source flame atomic absorption spectrometry (HR-CS FAAS and LS FAAS, respectively) were applied for Pb determination in unleaded aviation or automotive gasoline that was dissolved in methyl-isobutyl ketone. When using HR-CS FAAS, a structured background (BG) was registered in the vicinity of both the 217.001nm and 283.306nm Pb lines. In the first case, the BG, which could be attributed to absorption by the OH molecule, directly overlaps with the 217nm line, but it is of relatively low intensity. For the 283nm line, the structured BG occurs due to uncompensated absorption by OH molecules present in the flame. BG lines of relatively high intensity are situated at a large distance from the 283nm line, which enables accurate analysis, not only when using simple variants of HR-CS FAAS but also for LS FAAS with a bandpass of 0.1nm. The lines of the structured spectrum at 283nm can have “absorption” (maxima) or “emission” (minima) character. The intensity of the OH spectra can significantly depend on the flame character and composition of the investigated organic solution. The best detection limit for the analytical procedure, which was 0.01mgL−1 for Pb in the investigated solution, could be achieved using HR-CS FAAS with the 283nm Pb line, 5pixels for the analyte line measurement and iterative background correction (IBC). In this case, least squares background correction (LSBC) is not recommended. However, LSBC (available as the “permanent structures” option) would be recommended when using the 217nm Pb line. In LS FAAS, an additional phenomenon related to the nature of the organic matrix (for example, isooctane or toluene) can play an important role. The effect is of continuous character and probably due to the simultaneous efficient correction of the continuous background (IBC) it is not observed in HR-CS FAAS. The fact that the effect does not depend on the flame character indicates that it is not radiation scattering. For LS FAAS, the determination of Pb using the 283nm line, a 0.1nm bandpass and a fuel lean flame is strongly recommended. The analysis of certified reference materials, recovery studies and the analysis of real samples with low Pb content supported the satisfactory accuracy of Pb determination in automotive or aviation gasoline when the recommended analytical variants are applied.The studies in this work shed new light on spectral phenomena in air-acetylene flames. The structured background due to absorption by the OH molecules must be taken into account during Pb determination in other materials as well as in some other elemental determinations, especially at low absorbance levels. The usefulness of HR-CS FAAS for revealing and investigating a structured background was demonstrated. HR-CS FAAS does not reveal fully corrected spectral effects with a continuous character, which can be found in LS FAAS.

Determination of total sulfur concentrations in different types of vinegars using high resolution flame molecular absorption spectrometry

Total sulfur concentrations in vinegars were determined using molecular absorption of carbon monosulfide (CS) determined with a high-resolution continuum source flame atomic absorption spectrometer. The molecular absorption of CS was measured at 258.056nm in an air–acetylene flame. Due to non-spectral interference, as well as the different sensitivities to some sulfur compounds, all sulfur species were oxidized to sulfate using a HNO3 and H2O2 mixture and the analyte addition technique was applied for quantification. The limit of detection (LOD) and limit of quantification (LOQ) were 11.6 and 38.6mgL−1, respectively. The concentrations of sulfur in various vinegars ranged from ⩽LOD to 163.6mgL−1.

Preconcentration and Determination of Copper(II) by Novel Solid-Phase Extraction and High-Resolution Continuum Source Flame Atomic Absorption Spectrometry

ABSTRACTAmberlite XAD-4 modified with N-para-anisidine-3,5-di-tert-butylsalicylaldimine was investigated as a new chealting sorbent for the selective separation and preconcentration of Cu(II). The metal ion was retained by chemical sorption on the modified resin, eluted by hydrochloric acid, and determined by high-resolution continuum source flame atomic absorption spectrometry. The prepared resin was characterized for the solid-phase extraction of Cd2+, Co2+, Cr3+, Cu2+, Fe3+, Mn2+, Ni2+, Pb2+, and Zn2+ in a column. The influence of the pH, the mass of solid phase, eluent, flow rate, and sample volume was optimized. Using the optimum conditions, only Cu(II) showed quantitative sorption at the 95% confidence level, and the recoveries of the other metal ions were below 80%. A preconcentration factor 125 was obtained for Cu(II) with a limit of detection of 0.56 µg L−1. The method was used for the determination of Cu(II) in tap water, river water, tomato leaves, and fish. The relative standard deviation and the relative error were lower than 7%.

Spectral aspects of the determination of Si in organic and aqueous solutions using high-resolution continuum source or line source flame atomic absorption spectrometry

High-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS) was applied to reveal and investigate spectral interference in the determination of Si. An intensive structured background was observed in the analysis of both aqueous and xylene solutions containing S compounds. This background was attributed to absorption by the CS molecule formed in the N2O–C2H2 flame. The lines of the CS spectrum at least partially overlap all five of the most sensitive Si lines investigated. The 251.611nm Si line was demonstrated to be the most advantageous. The intensity of the structured background caused by the CS molecule significantly depends on the chemical form of S in the solution and is the highest for the most-volatile CS2. The presence of O atoms in an initial S molecule can diminish the formation of CS. To overcome this S effect, various modes of baseline fitting and background correction were evaluated, including iterative background correction (IBC) and utilization of correction pixels (WRC). These modes were used either independently or in conjunction with least squares background correction (LSBC). The IBC+LSBC mode can correct the extremely strong interference caused by CS2 at an S concentration of 5% w:w in the investigated solution. However, the efficiency of this mode depends on the similarity of the processed spectra and the correction spectra in terms of intensity and in additional effects, such as a sloping baseline. In the vicinity of the Si line, three lines of V were recorded. These lines are well-separated in the HR-CS FAAS spectrum, but they could be a potential source of overcorrection when using line source flame atomic absorption spectrometry (LS FAAS). The expected signal for the 251.625nm Fe line was not registered at 200mgL−1 Fe concentration in the solution, probably due to the diminished population of Fe atoms in the high-temperature flame used. The observations made using HR-CS FAAS helped to establish a “safe” level of the matrix components S, V, and Fe in the determination of Si using both HR-CS FAAS and LS FAAS. Under the best conditions, the instrumental detection limits for LS FAAS and for HR-CS FAAS, as well as the characteristic concentration values, were similar. Unusual calibration curves were observed in HR-CS FAAS. The curves showed an inflexion point that divided them into two linear parts with distinctly different slopes.

Separation and Preconcentration of Aluminum by Candida albicans Immobilized on Cellulose Acetate Biomass

In the present study, separation parameters of aluminum ions from aqueous solutions by Candida albicans immobilized on the cellulose acetate biomass (CAICAB) were investigated. The optimum experimental conditions for the preconcentration of aluminum were investigated. Amount of CAICAB, effect of common matrix ions and capacity of CAICAB were also obtained. 5 mL of 2 mol L−1 HCl were used for elution of adsorbed aluminum ions on CAICAB. After elution, analyte ions were determined by high resolution continuum source flame atomic absorption spectrometry. Under the optimized conditions, limit of detections for aluminum and adsorption capacity of CAICAB were 0.12 and 327.5 µg g−1, respectively. The method developed was applied to the separation and determination of aluminum in water samples.