Search

Simple and inexpensive custom-made CVG and DBD devices were developed and applied to demonstrate methylmercury adsorption on particulate matter.

Nanoparticles such as zinc oxide nanoparticles (ZnO-NP) that are incorporated in consumer and industrial products have caused concern about their potential ecotoxicological impact when released into the environment. Bivalve mollusks are susceptible targets for nanoparticle toxicity since nanomaterials can enter the cells by endocytosis mechanisms. The aim of this study was to evaluate the influence of ZnO-NP on the redox metabolism in Limnoperna fortunei and the DNA damage after exposure to ZnO-NP. Adult bivalves were incubated with 1-, 10-, and 50-μg mL-1 ZnO-NP for 2, 4, and 24 h. Ionic Zn release, enzymatic and non-enzymatic antioxidant activity, oxidative damage, and DNA damage were evaluated. Oxidative damage to proteins and lipids were observed after 4-h exposure and returned to baseline levels after 24 h. Superoxide dismutase levels decreased after 4-h exposure and increased after 24 h. No significant alteration was observed in the catalase activity or even DNA double-strand cleavage. The dissociation of ZnO may occur after 24 h, releasing ionic zinc (Zn2+) by hydrolysis, which was confirmed by the increase in the ionic Zn concentration following 24-h exposure. In conclusion, ZnO-NP were able to induce oxidative stress in exposed golden mussels. The golden mussel can modulate its own antioxidant defenses in response to oxidative stress and seems to be able to hydrolyze the nanoparticles and consequently, release Zn2+ into the cellular compartment.

Palladium nanoparticles were evaluated as a potential chemical modifier for lead determination by high-resolution continuum source graphite furnace atomic absorption spectrometry. Hydrophilic palladium nanocubes and palladium nanospheres were synthesised with sizes varying from 3 to 22 nm. Positive effects in terms of sensitivity and thermal stability upon the use of palladium nanoparticles were observed, especially using the 3 nm spherical-shaped. The mass of modifier influenced the thermal stability and relative signal intensity of the analyte, although the effectiveness of the modifier appeared to be suppressed to an important extent in the presence of matrix components of the leached extracts obtained from petroleum wastes. The optimised pyrolysis and atomisation temperatures were, respectively, 800 °C and 2300 °C, using 200 ng of 3 nm palladium nanoparticles. The limit of detection (4 µg L−1) and the precision (better than 18 %) were considered satisfactory for the proposed analysis. The method accuracy, evaluated by recovery tests and by comparison with the results obtained using inductively coupled plasma mass spectrometry, was proven adequate to enable the determination of Pb in leached extracts from petroleum waste. The method was successfully applied to determine lead in leached extracts obtained from oily sludge and drill cuttings and the obtained concentrations ranged from −1.

This work presents the results from the first investigation of Br and Cl isotopic partitioning in Southern Ocean sea ice. The sea ice samples were collected during the Australian-led Sea Ice Physics and Ecosystem eXperiment-2 (SIPEX-2) marine voyage in austral spring of 2012 (26 Sept – 10 Nov), within the area bounded by 115–125°E and 62–66oS off the East Antarctic coast. Multicollector inductively coupled plasma mass spectrometry was used to provide isotopic data for bromine and chlorine. Bromine concentrations ranged from 710 ± 20 μg L−1 to 31440 ± 570 μg L−1 and chlorine concentrations ranged from 218 ± 12 mg L−1 to 7945 ± 351 mg L−1. Bromine and chlorine concentrations were positively correlated with a slope of 0.0038, consistent with the seawater Br/Cl ratio of 0.0035. Bromine isotopic compositions (denoted δ81Br with respect to SMOB isotopic reference) varied from −0.64 to 0.10‰ with a mean of −0.16‰ and standard deviation of 0.04‰. Chlorine isotopic compositions (denoted δ37Cl with respect to SMOC isotopic reference) varied from −1.10‰ to 0.43‰ with a mean of −0.26‰ and standard deviation of 0.10‰. Despite their strong concentration correlation, there was a much less consistent relation between Br and Cl isotopic compositions and great variability within individual sea ice cores. The samples showing the largest degree of fractionation in their Br and Cl isotopic compositions were found deepest in the sea ice samples. Multiple parameters may influence isotopic fractionation processes in sea ice, including ice texture, age, salt content, and algal biomass content (represented by chlorophyll-a concentrations), although no single factor was found to consistently correlate with the bromine or chlorine isotopic signature. We consider the possibility of isotopic fractionation resulting from brine rejection and desalinization processes.

This work focused on the evaluation of extraction protocols using convective heating and HNO3 or HCl solutions regarding their performance towards fractionation analysis of mercury (inorganic and organic fractions) in oily sludge samples using cold vapor atomic fluorescence spectrometry (CV-AFS). Sample mass, volume of extraction, temperature, type and concentration of the extractant solution (HNO3 or HCl) and time of extraction were evaluated. Doehlert and Box–Behnken designs were employed to generate response surfaces that would allow multivariate evaluation of experimental conditions to be carried out. After statistical treatment and response surface evaluation, the conditions 100 mg of sample, 90 °C, 10 mL of 8.0 mol L−1 HNO3 and 10 minutes of extraction were selected and applied in a desirability function to combine the maximum extraction efficiency of Hg species and the least acceptable CH3Hg+ conversion rate, as well as the highest recovery of Hg2+ and CH3Hg+. Three different oily sludge samples were analyzed, resulting in 45–66% of Hg2+ fraction, negligible CH3Hg+ to Hg2+ conversion and recoveries of 49–102% for Hg2+ and 89–106% for CH3Hg+. The analytical results were compared to those obtained by high-performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS) and no statistical differences were observed at a 95% confidence level. Limits of detection (LOD) and quantification (LOQ) achieved for CV-AFS were 0.07 and 0.2 ng g−1, respectively, whereas the LOD and LOQ achieved using HPLC-ICP-MS were 0.01 and 0.03 μg g−1. The concentration of organic species of Hg in oily sludge samples was below the LOD of both techniques.

The feasibility of photochemical vapor generation for the production of volatile Ni species was evaluated and applied to the analysis of acetic acid leachates obtained from oily sludge samples. Sludge samples originating from a petrochemical plant were submitted to extraction using standardized procedures with solutions adjusted to pH 2.88 or 4.93, with acetic acid. The leachate solutions were subsequently treated with a mixture of acetic and formic acid and exposed to UV radiation from a Hg discharge lamp; the irradiated solution was pumped to a gas-liquid separator and the volatile species were transported by a stream of argon for detection using inductively coupled plasma mass spectrometry. Experimental variables, including the nature and concentration of low molecular weight acids, irradiation interval, carrier gas flow rate and the effect of concomitant species on the efficiency of photochemical production of volatile Ni species were systematically evaluated. Oxygenated anions, particularly nitrate, were found to suppress the analytical signal, whereas the effect of cationic species depended on the nature of the cation. Lead was found to induce substantial signal suppression even at ppb levels. Considering the significant influence of concomitant species on the overall efficacy of the photochemical process, isotope dilution calibration was adopted as a strategy to overcome non-spectral interferences. Under optimized conditions, relative standard deviations better than 8.5% were achieved, along with detection limits better than 40 μg L−1. The accuracy was statistically attested upon comparison of the results to those obtained from the analysis of leachates using sample introduction via pneumatic nebulization. The proposed photochemical vapor generation setup was proven efficient to carry out the determination of Ni in the leachates, although the technique is highly sensitive to the presence of concomitants.

The results originated from the application of a simple and straightforward photochemical reactor to generate volatile species from noble metals (Au, Ir, Pd, Pt and Rh) are presented. Seawater samples were spiked with known amounts of the analytes and mixed with formic acid, followed by irradiation of the solution at 253.7 nm. The irradiated solution was driven to a gas–liquid separator and the volatile species were carried by an argon stream for detection using inductively coupled plasma mass spectrometry. Parameters such as formic acid concentration, carrier gas flow rate, UV irradiation period and RF power were evaluated. The optimum conditions were determined as 20% (v/v) formic acid, 1.0 L min−1 Ar, 45 s of UV exposure for Au, Pd, Pt and Rh or 120 s for Ir and 1300 W ICP RF power. Evaluation of potential interferences has shown that the addition of Cu2+ at ppm levels improved the overall efficiency of the photochemical process for Ir and Rh. Hence, Cu2+ was added as a modifier prior to the quantitation of Ir and Rh. Three seawater samples collected locally were used to evaluate the ability to carry out quantitative analysis of the investigated elements. The concentration of noble metals was, as expected, below the quantification limit, but recovery tests were successfully performed. Detection limits ranged from 0.02 to 0.1 μg L−1. Typical relative standard deviations were lower than 13% and the method was proven successful as an alternative to carry out the analysis of mildly diluted seawater samples.

High-resolution graphite furnace molecular absorption spectrometry combined with samples prepared as suspensions were used for the quantification of Si in geological samples and in spent catalysts used for petrochemical processing. Measurements at the main Si resonance line at 251.6110 nm were proven unfeasible due to the formation of a quasi-continuous signal, which resulted in significant memory effect. An alternative was to monitor the fine rotational spectrum of SiO, which allowed memory effect-free measurements. A SiO rotational line centered at 231.9373 nm was selected to carry out quantitative analysis of Si at high percent concentrations in a variety of solid samples. Pyrolysis and vaporization temperatures were evaluated and optimized as 800 °C and 2400 °C, respectively, without the need to use a chemical modifier. Attempts to produce SiO molecules from acidified aqueous standards containing Si were unsuccessful, as the molecule could only be produced from solid samples, likely due to the formation mechanism that involves thermal decomposition of silicates. Hence, solid samples were prepared as suspensions in 0.14 mol L−1 HNO3. Calibration was performed using a series of suspensions prepared from a gabbro rock certified reference material (CRM), resulting in a limit of detection of 0.5% (m/m). The accuracy of the method was attested by the analysis of several CRM, including rocks, soils and sediments. Solid spent petrochemical catalyst samples were also analyzed and 97–114% recovery was obtained by spiking the catalyst suspensions with a CRM. The good accuracy demonstrated that the formation of SiO is free from matrix effects and highly efficient under the adopted conditions. Overall, the method was proven accurate and consists on a simple and fast alternative to determine Si in silicate-rich samples.

The phenolic composition, antioxidant capacity and bioaccessibility of the minerals of thirteen honey samples from nine different species of stingless bees ( Meliponinae ) were determined in this study. Twenty-six phenolic compounds were found. The major phenolic compounds were salicylic acid (8.02–94.8 μg 100 g 1 ), p- coumaric acid (4.54–64.3 μg 100 g 1 ), naringin (4.00–32.0 μg 100 g 1 ) and taxifolin (12.0–1920 μg 100 g 1 ). Moreover, the presence of mandelic acid, caffeic acid, chlorogenic acid, rosmarinic acid, aromadendrin, isoquercetrin, eriodictyol, vanillin, umbelliferone, syringaldehyde, sinapaldehyde and carnosol in stingless bee honeys was reported for the first time. The study also states that the abundant minerals in the samples were potassium (263–4980 μg g 1 ), followed by calcium (88.7–138 μg g 1 ), sodium (12.7–261 μg g 1 ) and magnesium (25.9–231 μg g 1 ). The estimation of the minerals bioaccessibility demonstrated high fractions (73.62–107.6% of the total concentrations). Stingless bee honey has considerable concentrations of phenolic compounds and macro minerals (K, Ca, Na and Mg) as well as a related antioxidant capacity, suggesting a source of natural antioxidants.

This paper describes an evaluation of current test methods for total sulfur determination in biodiesel, according to international specifications requirements, which was carried out using isotope dilution and inductively coupled plasma mass spectrometry (ID-ICP-MS) as a metrological tool. Closed vessel microwave-assisted digestion was employed using nitric acid and hydrogen peroxide as the decomposition medium, followed by isotope spike with 34 S dissolved in n-propanol. In order to overcome the spectral interference due to the presence of diatomic oxygen molecules in the ion beam, a reaction cell was used. Under optimized operating conditions, the determination of sulfur could be carried out at m / z +16, i.e., monitoring SO + signal for both sulfur isotopes. The ID-ICP-MS method was able to provide reference values for a series of commercial samples, which resulted in the evaluation of an extended concentration range. Sample sets including commercial biodiesel and inorganic sulfur-enriched biodiesel were employed as a means to evaluate the accuracy of routine methods for possible different sulfur species. No statistically significant difference was observed among the values measured with the proposed method and with the standard methods by UV fluorescence spectrometry and inductively coupled plasma optical emission spectrometry.

An in vitro method involving simulated gastrointestinal digestion was used to assess the bioaccessibility of fifteen minerals, twenty-two phenolic compounds and the antioxidant capacity in jucara fruit during seven ripening stages. For minerals and phenolics, respectively, initial contents were up to 1325.9 and 22.9mg100g-1, whereas after in vitro digestion, the maximum values were 556.7 and 14.43mg100g-1 (dry matter). Antioxidant capacity, determined by 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH) and ferric reducing antioxidant power (FRAP), after in vitro digestion decreased 51-78% when compared to the crude extract. Bioaccessible fractions of quercetin, protocatechuic and p-coumaric acids presented positive and significant correlation with results of DPPH and FRAP. Furthermore, our study demonstrated that the ripening stages of jucara fruit influenced the bioaccessibility of compounds and antioxidant capacity, which presented higher levels in purple fruits collected 42-69days after the appearance of the red berries on bunches.

The aim of this study was to characterize the inorganic chemical composition of fine inhalable atmospheric particulate matter (PM_(2.5)) in medium-sized cities in Brazil. These cities account for a significant proportion of the population and are growing at rates above the national average, thereby demonstrating the importance of carefully analysing the possible impact of such growth on air quality over the coming decades. In 2013 and 2014, this study collected PM_(2.5) samples from sites in the cities of Londrina and Maringa in two seasons: winter and summer. The mean concentration of PM_(2.5) ranged from 4.4 μg m^(-3) and 3.7 μg m^(-3) during the summer to 10.3 μg m^(-3) and 8.0 μg m^(-3) in winter in Londrina and Maringa, respectively. The analysis of the major water-soluble ions, nitrate, sulphate and chloride, showed that they accounted for between 16.5% and 35.1% from the mass of PM_(2.5), with sulphate providing the greatest contribution in all the campaigns. The nitrate/sulphate ratios ranged from 0.2 and 0.6, which are similar to the figures cited in the literature for other regions of the world. Although the PM_(2.5) concentrations are much lower than those observed in Asia and in Sao Paulo the participation of ions (%) is very close to that observed in Asian cities and significantly higher than the values recorded in other areas of Brazil, possibly as a result of the increased influence of burning of biomass and waste. The metals Zn, Pb, Cu and Mn found in the samples from all campaigns indicate that, in general, mobile sources are the main contributor to PM_(2.5). The winter campaigns showed the highest concentrations of black carbon equivalent (BCe). Absolute principal component analysis and enrichment factor analysis indicate the contribution of vehicular emission sources and biomass and waste burning to the inorganic chemical composition of PM_(2.5).

The determination of Gd, La, Tb, Tm, Yb and Y in a variety of digested geological and catalyst samples was carried out using electrothermal vaporization inductively coupled plasma mass spectrometry. The analytes were extracted into CHCl3 using dispersive liquid–liquid microextraction (DLLME) with 8-hydroxyquinoline as the chelating agent and ethanol as the dispersing solvent. Multivariate optimization of the experimental parameters associated with DLLME was employed to reduce the number of experiments and to evaluate the interaction between variables. Aerosol carrier effects associated with Pd, Zr or a poly(tetrafluoroethylene) (PTFE) slurry, as well as their combinations, were evaluated as to their ability to increase the transportation efficiency of the analytes from the graphite tube to the inductively coupled plasma. Palladium (1.0 μg) was efficient in equalizing the transportation efficiency of the analytes vaporized from aqueous standards and digested samples, both submitted to DLLME, which allowed calibration against aqueous standards to be carried out. Detection limits as low as 0.08 ng g−1 and enhancement factors of up to 323 were obtained. Two spent catalyst samples from the petrochemical industry and three certified reference materials (CRMs) of geological origin (granite, gabbro rock and diabase rock) were analyzed. Three distinct microwave-assisted digestion procedures were evaluated, consisting of mixtures of HNO3, HCl, H2O2, HF and H3BO3, and the joint use of the first three reagents was found to be sufficient to provide accurate results for the investigated rare earth elements. Good agreement between determined and certified values, at a 95% statistical confidence level, was achieved for the CRMs, whereas the concentrations of REEs obtained for the catalyst samples were compared to the results obtained from the direct analysis of digested samples using pneumatic nebulization, also with adequate statistical agreement.

Grape and grape derivatives contain a variety of antioxidants that have gain increasing interest for functional foods applications. The chemical composition of grapes is mainly related to grape variety and cultivation factors, and each grape constituent exhib its unique characteristics regarding its bioactive properties. This study investigated the chemical composition and the effect of drying on the bioactive content of the non-pomace constituent obtained in the processing of organic and conventional grape juices from V. labrusca L. The non-pomace samples were analyzed for polyphenols, monosaccharides, antioxidant activity and elemental composition and the effect of drying on the bioactive composition was evaluated in samples subjected to lyophilization and drying with air circulation. The analyses revealed high concentrations of proanthocyanidins, flavanols and anthocyanins, and high antioxidant capacity of the organic and conventional samples. The drying processes reduced significantly (P

This work presents a direct and straightforward approach for the determination of trace elements in fish muscle, oyster, and bovine liver via direct solid sample analysis (SS) using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). The preliminary studies revealed the presence of spectral interferences at the analytical line of Ni at 231.096 nm, which could be corrected subtracting the spectrum of SiO and PO from the sample spectra using least-squares background correction. Moreover, all meat samples were proven homogeneous according to the homogeneity factor (H e) (all values were

Titanium dioxide nanoparticles (TiO2 NP) are present in several daily use products, and the risks associated with their bioaccumulation must be stablished. Thus, an evaluation of several toxicological-related effects was conducted after intraperitoneal injection of TiO2 NPs in mice. Mice were divided into two groups, which received 2 mg kg−1 day−1 of TiO2 NPs or vehicle saline. Assessments of body and organ weight as well as biochemical, hematological, and histopathological analyses were performed in order to evaluate adverse effects. The results showed that treatment resulted in an increased visceral and abdominal fat deposition, as well as a mononuclear inflammatory infiltrates in the abdominal fat tissue. The TiO2 NPs induced significant decrease in the weight gain and splenomegaly. Additionally, TiO2 NP-treated mice showed altered hematological parameters and significant liver injuries, which were characterized by histopathological and biochemical changes. Our results also indicated that TiO2 NPs were absorbed and significantly accumulated in the spleen, liver, and kidney. These results showed the ability of TiO2 NPs to infiltrate different organs and to induce inflammation and liver and spleen damage with visceral fat accumulation. The data obtained are useful for the governmental authorities to legislate and implement regulations concerning the use and the production of this kind of material that might be hazardous to the living beings, as well as to the environment.

This study evaluates the nutritional potential of Sarcocornia ambigua as new a source of minerals. The mineral concentrations of two different growing populations (natural occurrence and irrigated) of S. ambigua were evaluated using inductively coupled plasma mass spectrometry. In all samples, the mineral present in highest amounts was potassium (K) (19–24 μg g−1), followed by magnesium (Mg) (8.6–14 μg g−1) and then calcium (Ca) (2.6–4.0 μg g−1). In addition, in vitro bioacessibility assay demonstrated that very high fraction (65–80%) of these K and Mg (80 and 65%) of total concentration of these elements is bioacessible from S. ambigua analyzed. The trace elements vanadium (V), chromium (Cr), cobalt (Co), copper (Cu) and lithium (Li) have more than above 50% of total concentration was found bioaccessible. In all cases, mass balance was verified by carrying out the total digestion of the remaining residue and the relationship between total concentration and bioaccessibility. The data related to the concentrations and the bioaccessible fractions of the minerals provide a starting point for more complex and in-depth evaluations from the nutritional point of view, including the establishment of a recommended daily dietary intake for this plant.

A novel method using photochemical vapour generation (PVG) for the determination of iodine in alcoholic beverages by inductively coupled plasma mass spectrometry (ICP-MS) is presented. The procedure consisted in simply diluting 1.0 mL of an alcoholic beverage (cachaca, vodka, whisky, brandy and gin were analyzed) to a final volume of 15 mL with deionized water prior to introduction in the PVG reactor for the generation of volatile iodine species. The native ethanol content in the samples (approximately 40 % v/v, before dilution) was proven sufficient to produce radicals upon UV irradiation, which ultimately resulted in the release of volatile iodine compounds to the gas phase. The process was systematically evaluated to reach the optimum operating conditions of 1.0 L min-1 Ar as the carrier gas, 1400 W ICP RF power, sample flow rate of 8.08 mL min-1 and 49 s of sample solution exposition to UV photons in the PVG reactor. Two distinct gas-liquid separators (GLS) with internal volumes of 3.1 and 6.5 mL were evaluated. The GLS with an internal volume of 6.5 mL was selected, as it resulted in higher sensitivity for the analyte. Matrix effects required standard addition calibration to be employed to determine the iodine concentrations, which ranged from ca. 21 to 386 μg L-1. Detection and quantification limits were determined as 0.1 and 0.3 μg L-1, respectively. The trueness was verified by comparing the results with those obtained by ICP-MS with pneumatic nebulization, following sample digestion in closed vessels. No significant statistical difference was observed when a paired t-test was applied and the sensitivity achieved from analyte introduction using PVG was 64 % higher when compared to the use of a pneumatic nebulizer. The samples were also spiked with known amounts of the analyte and recoveries ranged from 95 to 105 %, with relative standard deviations better than 9 %.

Atmospheric particulate matter (APM) monitoring is a fundamental tool for air pollution management and control. However, the limited amount of an APM sample that is typically available upon collection using specific devices may be a limiting factor to promote reliable chemical analysis. Direct solid analysis is thus a cost-effective alternative to be applied for this purpose, since it simplifies the handling of samples, combining faster analysis to maximum detectability with minimum sample consumption. This study presents the development of methods for the determination of beryllium, cadmium and lead in inhalable particulate matter (PM10) using direct solid analysis and high-resolution continuum source electrothermal atomic absorption spectrometry. The temperature program and the use of chemical modifiers were optimized for each individual analyte. Zirconium was used as a permanent modifier for the determination of Be, whereas Pd and Mg were co-injected as chemical modifiers for the determination of Cd and Pb. The potential interferences and calibration strategies were also evaluated. Under optimized conditions, calibration against aqueous standards was proven feasible and detection limits of 0.001, 0.001 and 0.004 ng m−3 for Be, Cd and Pb, respectively, were achieved. The methods were applied to the determination of the referred analytes in 28 samples of PM10 collected at an urban site in the city of Florianopolis, in the State of Santa Catarina, Brazil. Chemometric treatment of data considering analyte content in addition to meteorological parameters (accumulated rainfall, sunlight incidence and wind speed) showed a detectable correlation between these parameters. Samples could be statistically differentiated based on separate loadings for Cd and Pb, which was opposite to Be, for instance. Hence, there is the possibility to correlate these parameters in order to establish a relationship between the origin of the elements in the PM10 samples and the impact of meteorological conditions on their distribution in solid atmospheric particles.

Gadolinium-based contrast agents (GBCA) are widely used to enhance tissue contrast during magnetic resonance imaging (MRI) procedures. However, free Gadolinium (Gd) is undesirable as a drug substance, due to its high toxicity. Consequently, a coordinating ligand is required to keep it in solution and to increase tolerance. In order to achieve an adequate performance, GBCA must be administered in relatively large amounts. Chelate amounts are around 13–20 g and for Gd alone, this may amount to 3.3 g. Taking into account the route of administration, impurities in GBCA may be significant. Gadolinium occurs in nature along with 16 other elements known collectively as rare earth metals (RE), which are found throughout the earth's crust in minerals such as monazite. Gadolinium oxide corresponds to 0.7–4.0% of the RE present in minerals, and the sum concentration of RE in minerals is around 4%. Rare earth metals are difficult to separate, as the chemical and physical properties of one RE are significantly similar to those of others. In this study, the presence of other RE in GBCA formulations was investigated. Different lots of Magnevist®, Viewgam®, OptiMARK®, Omniscan®, Dotarem®, and Gadovist® were analyzed. Inductively-coupled plasma mass spectrometry and atomic absorption spectrometry were used for RE determination. Procedure optimization included sample decomposition and method validation for element determination. The results showed that Sc, Y, La, Ce, Pr, Nd, Eu, Tb, Tm, Dy, Ho, and Er were present in the 22 samples analyzed. Terbium, Thulium, Europium, and Lanthanum were, on average, found in the highest amounts, which were 0.42 mg/L, 0.17 mg/L, 0.17 mg/L, and 0.16 mg/L, respectively. These results could be attributed to the similarity among Europium, Gadolinium, and Terbium. They are in sequence in the periodic table and therefore present very close ionic radii, restricting their separation. Considering the sum of all RE, Viewgam® was the most contaminated formulation (mean of 2.16 mg/L) and Magnevist® the least (mean of 0.64 mg/L). Although the RE are chemically similar, the other RE do not perform as Gd as a contrast agent; therefore, their presence in formulations may be a matter of concern.

In this work, a simple, fast and sensitive method for the determination of Mn, Ni, Rb and Sr in powdered samples of guarana ( Paullinia cupana ), catuaba ( Anemopaegmaglaucum ), ginseng ( Panax ginseng ), ginger ( Zingiber officinalis ), mate ( Ilex paraguariensis ) and coffee ( Coffea arabica ) was developed using direct solid sample analysis and high-resolution continuum source electrothermal atomic absorption spectrometry. The temperature program of the graphite furnace was optimized and the determination was carried out without the use of chemical modifiers. Calibration against a solid reference material was compared to calibration against aqueous standards and no significant differences were observed for Mn, Rb and Sr determination, whereas for Ni the difference in sensitivity was as high as 20%, indicating that calibration using a solid reference material should be adopted. Sixteen samples of stimulant plants from a local market were analyzed for trace elements, total phenolic compounds and antioxidant activity. Trace elemental content ranged from 0.08 μg g − 1 (Ni) to 135 μg g − 1 (Mn), total phenolics ranged from 3.37 ± 0.02 to 34.28 ± 0.04 mg GAE g − 1 , and antioxidant activity ranged from 1.15 ± 0.65 to 10.32 ± 0.21 TE mmol g − 1 . In order to carry out chemometric classification of the plant species, PCA was employed using data from elemental and phenolics contents of the plants, as well as their antioxidant activities. The joint use of these parameters allowed successful distinction between species, showing that these data can be used to discriminate between different stimulant plants.

Chlorine isotope ratio measurement using multi-collector ICP-mass spectrometry (MC-ICP-MS) with sample introduction using traditional pneumatic nebulization suffers from spectral interference in addition to low sensitivity. Pronounced memory effects may jeopardize the accuracy of the results and/or the sample throughput. In this work, these limitations were overcome by using (i) high mass resolution (mass resolving power of about 10 000) to resolve spectral interference, (ii) 5 mmol L−1 NH4OH as wash solution to avoid memory effects and (iii) a Cl concentration of ≥70 mg L−1. The major cation load of seawater and chloride salts (NaCl, KCl) sample solutions was efficiently removed without affecting the original isotopic composition of Cl via cation exchange chromatography with Dowex® 50WX8 resin. The method developed was demonstrated to be accurate and precise, as attested by the measurement result for the 37Cl/35Cl isotope ratio in NIST SRM 975a (experimental value of 0.319765 ± 0.000022, compared to a reference value of 0.319768 ± 0.000187 and a precision of ∼0.007% RSD, n = 3), additionally, the δ37Cl value (vs. standard mean ocean chlorine, SMOC) was determined for five different standards; the values ranged from −0.54 to +0.89‰.

The aim of this study was to evaluate the effect of ripening on the individual phenolic compounds, total anthocyanins and antioxidant capacity of jucara fruit. The color, moisture, total protein, total lipids, fatty acids and mineral contents were also evaluated. A total of eleven phenolic compounds were identified during the ripening of jucara fruit by HPLC–ESI-MS/MS. Rutin and quercetin showed highest levels at stages 6 and 7, with 0.27 to 0.28 mg 100 g− 1 and 1.25 to 1.48 mg 100 g− 1, respectively. The skin color of the fruit during ripening changed from red to black, favored by the accumulation of anthocyanins (507.57–634.26 mg cyanidin 3-glucoside 100 g− 1 fresh matter). In addition, these compounds (quercetin, rutin and anthocyanins) showed positive correlation with the antioxidant capacity, which explains the high antioxidant potential of jucara fruit observed in DPPH and FRAP assays. The results revealed that the pulp of the jucara fruit collected at the end of ripening (stages 5 to 7) also presents adequate nutritional potential for consumption, providing higher levels of protein, lipids, oleic and linoleic acids, potassium, calcium, iron and manganese.

Cabernet Sauvignon and Merlot wines produced with grapes dried under controlled conditions (7 °C, 35% relative humidity and airflow of 12 m 3 /s) were chemical and sensory characterized. Cabernet Sauvignon and Merlot grapes were vinified at the time of harvest (control wines) and after 30 and 40 g/100 g dehydration to wines produced with dried grapes. The Merlot wine produced with 40 g/100 g dried grapes, and the Cabernet Sauvignon wine produced with 30 g/100 g dried grapes, showed the highest levels of total polyphenols and total antioxidant activity. The elemental content was highest in wines produced with dried grapes. Sensory characterization showed that wines produced with dehydrated grapes exhibited typical descriptors of liqueur wines such as red-orange colour and high viscosity and alcoholic sensation. Principal component analysis confirmed that the grape dehydration process under controlled conditions influenced the chemical composition and sensory characteristics of the wines produced, mainly from 40 g/100 g dried grape, yielding differentiated and high value-added products.

A simple and accurate methodology for Br isotope ratio measurements in seawater by multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS) with pneumatic nebulization for sample introduction was developed. The Br+ signals could be measured interference-free at high mass resolution. Memory effects for Br were counteracted using 5 mmol L-1 of NH4OH in sample, standard, and wash solutions. The major cation load of seawater was removed via cation exchange chromatography using Dowex 50WX8 resin. Subsequent Br preconcentration was accomplished via evaporation of the sample solution at 90 A degrees C, which did not induce Br losses or isotope fractionation. Mass discrimination was corrected for by external correction using a Cl-matched standard measured in a sample-standard bracketing approach, although Sr, Ge, and Se were also tested as potential internal standards for internal correction for mass discrimination. The delta Br-81 (versus standard mean ocean bromide (SMOB)) values thus obtained for the NaBr isotopic reference material NIST SRM 977 and for IRMM BCR-403 seawater certified reference material are in agreement with literature values. For NIST SRM 977, the Br-81/Br-79 ratio (0.97291) was determined with a precision a parts per thousand currency sign0.08aEuro degrees relative standard deviation (RSD).

This work describes a methodology developed to carry out Cl determination in biological materials using electrothermal vaporization inductively coupled plasma mass spectrometry and direct solid sample analysis. The solid samples were directly weighed into graphite ‘cups’ and inserted into the graphite furnace. The RF power and the carrier gas flow rate were optimized at 1300 W and 0.7 L min− 1, respectively. Calibration could be carried out using aqueous standard solutions with pre-dried modifiers (Pd + Nd or Pd + Ca) or using solid certified reference materials with the same pre-dried modifiers or without the use of modifiers. The limit of quantification was determined as 5 μg g− 1 under optimized conditions and the Cl concentration was determined in five certified reference materials with certified concentrations for Cl, in addition to three certified reference materials, for which certified values for Cl were unavailable; in the latter case, the results were compared with those obtained using high-resolution continuum source molecular absorption spectrometry. Good agreement at a 95% statistical confidence level was achieved between determined and certified or reference values.

This study describes a new approach for direct solid sample analysis using thermoplastic starch (TPS) platforms for the determination of Mo and V by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). The TPS platform was prepared from a mixture of commercial corn starch (28% amylase and 72% amylopectin), with sorbitol as the plasticizer in a 70/30 mass-based ratio. Different parameters affecting the film composition, such as the proportion and plasticizer type, were evaluated taking into account the behavior in the graphite tube when the TPS platform was subjected to the heating program. The new sample introduction approach has been shown to increase the lifetime of the graphite tube significantly due to a much less pronounced tailing of the absorbance signals of elements such as Mo or V, which makes it possible to reduce atomization and cleaning times, compared to the use of a conventional graphite platform. Memory effects were significantly reduced using the starch-based platform, resulting in improved precision. The detection limit and characteristic mass were determined to be 25 pg and 7 pg for Mo, and 130 pg and 18 pg for V, respectively. The accuracy was confirmed by the analysis of a series of certified reference materials, including bovine liver, beef liver, rice flour and urban dust for Mo, and coal, urban dust, lichen and particulate matter for V.

A method has been developed for the determination of Al in commercial moisturizing body lotions using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). The most sensitive absorption line at 309.271 nm has been used for all determinations. The samples were prepared via a suspension with 0.3 mol L−1 nitric acid. Comparisons were made with pyrolysis and atomization curves without a modifier and using ruthenium and zirconium as permanent modifiers, to reduce the interaction of Al with the graphite surface and to improve the atomization efficiency of Al. 400 μg Zr was finally chosen as the best permanent modifier. The limits of detection and quantification were 30 ng g−1 and 95 ng g−1 Al, respectively. The proposed method was applied for 15 commercial moisturizing body lotions with results ranging between 0.17 ± 0.05 μg g−1 and 11.8 ± 0.43 μg g−1. Analyte addition tests have been used to evaluate the accuracy of the method and the recovery ranged between 103 and 110%, indicating that there was no serious matrix effect.

A new method for the direct analysis of coal using electrothermal vaporization inductively coupled plasma mass spectrometry and direct solid sample analysis was developed, aiming at the determination of Br and Cl. The procedure does not require any significant sample pretreatment and allows simultaneous determination of both elements to be carried out, requiring small mass aliquots of sample (about 0.5 mg). All operating parameters, including carrier gas flow-rate and RF power, were optimized for maximum sensitivity. The use of modifiers/aerosol carriers (Pd, Pd+Al and Pd+Ca) was evaluated, and the mixture of Pd and Ca was chosen, allowing pyrolysis and vaporization temperatures of 700°C and 1900°C, respectively. Chlorine was accurately determined using calibration against solid standards, whereas Br could also be determined using calibration against aqueous standard solutions. The limits of quantification were 0.03 μg g(-1) for Br and 7 μg g(-1) for Cl, and no spectral interferences were observed.

A new method has been developed for the determination of chlorine in biological reference materials using high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS) of the strontium mono-chloride (SrCl) molecule and direct solid sample analysis. The use of the SrCl molecule for high-temperature MAS was not described up to now in the literature. Preliminary time-dependent density functional theory calculations of the SrCl structure were carried out in order to obtain reasonable estimates of the absorption spectrum of the target molecule. The calculations, which were carried out at BHandHLyp/def2-QZVP level of theory, proved a very accurate and inexpensive way to get information about the spectrum of the SrCl molecule, which enabled us to perform the Cl determination with good sensitivity and specificity. The molecular absorption of the SrCl molecule has been measured using the wavelength at 635.862 nm, and zirconium and palladium have been evaluated as the chemical modifiers in order to increase the sensitivity of the gaseous SrCl molecule generated in the graphite furnace. The pyrolysis and vaporization temperatures were 600 °C and 2300 °C, respectively. Accuracy and precision of the method have been evaluated using biological certified reference materials of both animal and plant origins, showing good agreement with the informed and certified values. Limit of detection and characteristic mass were 1.0 and 2.2 ng, respectively. The results found using HR-CS GF MAS were in agreement (95% confidence level) compared to those obtained by electrothermal vaporization-inductively coupled plasma mass spectrometry.

We described the hyphenation of photo-induced chemical vapor generation with high performance liquid chromatography–atomic fluorescence spectrometry (HPLC–AFS) for the quantification of inorganic mercury, methylmercury (MeHg) and ethylmercury (EtHg). In the developed procedure, formic acid in mobile phase was used for the photodecomposition of organomercury compounds and reduction of Hg 2 + to mercury vapor under microwave/ultraviolet (MW/UV) irradiation. We optimized the proposed method studying the influence of several operating parameters, including the type of organic acid and its concentration, MW power, composition of HPLC mobile phase and catalytic action of TiO 2 nanoparticles. Under the optimized conditions, the limits of detection were 0.15, 0.15 and 0.35 μg L − 1 for inorganic mercury, MeHg and EtHg, respectively. The developed method was validated by determination of the main analytical figures of merit and applied to the analysis of three certified reference materials. The online interfacing of liquid chromatography with photochemical-vapor generation–atomic fluorescence for mercury determination is simple, environmentally friendly, and represents an attractive alternative to the conventional tetrahydroborate (THB) system.

The study proposes a simple and fast extraction-based procedure for the determination of trace elements in estuarine sediment samples by inductively coupled plasma mass spectrometry (ICP-MS). The extraction conditions were optimized using a central composite design. Optimum results were obtained when 100 mg of sediment sample was used followed by ultrasound-assisted extraction for 15 min with 7.50 mol L − 1 HF (1 mL HF) and 3.50 mol L − 1 HNO 3 (1 mL HNO 3 65% m/m). Calibration against aqueous standards was carried out with rhodium as an internal standard. The method was successfully applied for the quantitative extraction of As, Cd, Co, Cr, Cu, Ni, Pb, Sn, V and Zn. Detection limits ranging from 0.02 to 0.1 μg g − 1 and relative standard deviation lower than 8% were obtained. The method accuracy was assessed by using three certified reference materials and comparing the results from the extraction procedure with those obtained following microwave-assisted digestion of the samples; no statistical differences, based on t-test at a confidence level of 95%, were detected. The proposed method showed to be simple and fast and can be applied for sediment samples with the elimination of the sample digestion step prior to analysis.

A novel and sensitive method is described for the determination of Co, Ni and Te in alcoholic beverages by photochemical vapor generation combined with inductively coupled plasma mass spectrometry. Volatile species of Co, Ni and Te were liberated from mixed formic acid and acetic acid media following exposure to a UV source. Limits of quantification of 0.5, 0.1, and 0.4 μg L − 1 for Co, Ni and Te, respectively, were obtained, which correspond to improvements 9, 35, and 3 times more over those obtained with conventional pneumatic nebulization. Method accuracy was demonstrated by comparison of the determined Co, Ni and Te concentrations with those obtained following sample digestion and determination using conventional solution nebulization for sample introduction, resulting in good agreement at a 95% confidence level.

This work reports a simple approach for Br determination in coal using direct solid sample analysis in a graphite tube furnace and high-resolution continuum source molecular absorption spectrometry. The molecular absorbance of the calcium mono-bromide (CaBr) molecule has been measured using the rotational line at 625.315 nm. Different chemical modifiers (zirconium, ruthenium, palladium and a mixture of palladium and magnesium nitrates) have been evaluated in order to increase the sensitivity of the CaBr absorption, and Zr showed the best overall performance. The pyrolysis and vaporization temperatures were 800 °C and 2200 °C, respectively. Accuracy and precision of the method have been evaluated using certified coal reference materials (BCR 181, BCR 182, NIST 1630a, and NIST 1632b) with good agreement (between 98 and 103%) with the informed values for Br. The detection limit was around 4 ng Br, which corresponds to about 1.5 μg g − 1 Br in coal, based on a sample mass of 3 mg. In addition, the results were in agreement with those obtained using electrothermal vaporization inductively coupled plasma mass spectrometry, based on a Student t -test at a 95% confidence level. A mechanism for the formation of the CaBr molecule is proposed, which might be considered for other diatomic molecules as well.

Grape juice is a natural source of polyphenols with potential health benefits. The aim of this study was to assess the optimized basis of the pectinolytic activity through a multivariate design for the bioactive enrichment of polyphenols in grape juices and to evaluate the effect of pectinases on the extraction of minerals by ICP-MS and FAAS. Grape juices were treated with pectinases Everzym® Color and Rapidase® Smart at different conditions of enzyme concentration (0.16–1.84 g L−1), temperature (14.8–83.6 oC), and incubation time (9.6–110.5 min), and the effect on total phenolics, anthocyanin content, and antioxidant activity of juices were determined by employing a second-order central composite design in combination with response surface methodology. The different conditions showed significant variations in polyphenol levels of grape juices. For both of the enzymes, the increase of temperature and enzyme concentration led to a higher extraction of polyphenols, with a significant effect. Estimated effects depict a good correlation among dependent variables. For Rapidase, the optimized extraction of polyphenols was determined at an enzyme concentration of 1.57 g L−1 and at a temperature of 54.8 oC. For Everzym, higher concentrations of polyphenols were obtained at the enzyme concentration of 1.30 g L−1 at 46.8 oC. The extraction using the Rapidase enzyme significantly increased the levels of Na, K, Mg, and Fe in grape juices (p

The current study describes a simple and fast method for the determination of Ba, Cd, Co, Cr, Cu, Mn, Ni and Pb in tobacco samples. Commercial cigarettes obtained from local market stores were analysed by inductively coupled plasma mass spectrometry (ICP-MS) after ultrasound-assisted extraction in acidic medium, and the results were compared to those obtained following microwave-assisted digestion of the samples. The sonication time was evaluated from 0 to 60 min, and a 30 min extraction time was selected. The concentration of HNO3 was also optimised at 0.7 mol L−1. In order to verify the accuracy of the proposed method, a certified reference material was submitted to the same extraction protocol adopted for the samples, and good agreement with the certified values was obtained at a 95% confidence level, except for Co. The extraction of Pb was also semi-quantitative. A total of four tobacco samples were analysed, with concentrations ranging from 0.4 for Cr to 214.6 µg g−1 for Mn. The proposed method was d...

This work describes the method development process involved in the determination of Ag, Cd, Cu and Pb in biological samples by electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS), following dispersive liquid–liquid microextraction (DLLME). The parameters associated with DLLME such as HNO3 and diethyldithiophosphate (DDTP) concentrations, as well as the volumes of disperser (ethanol) and extracting (chloroform) solvents, were evaluated. The ICP-MS operating parameters (carrier gas flow rate and RF power) were also optimized. Several distinct approaches involving investigation on chemical modifiers (W, Ru, Pd and combinations), aerosol carriers (Na2SO4, ascorbic acid and diethyldithiophosphate – DDTP) and the effect of insertion of a L'vov platform on the transport efficiency from the ETV to the ICP and overall analytical performance were evaluated. The results suggest that the use of a platform and chemical modifiers lead to increased thermal stability, although the sensitivity is generally reduced when compared to the absence of modifiers and wall vaporization. Several calibration approaches were evaluated, including the combination of chemical modifiers and the use or absence of a L'vov platform inside the graphite tube. Accurate results were achieved for all elements upon the use of palladium as the aerosol carrier in combination with W and Ru as permanent chemical modifiers, demonstrating that the effective transportation of the analytes and equalization of the transport efficiency between samples and calibration solutions are carrier-dependent. To verify the accuracy of the proposed methodology, four certified reference biological materials were analyzed, with good agreement between certified and determined values. ‘Real’ samples were also analyzed following the optimized procedure. The proposed method resulted in detection limits between 0.001 and 0.09 μg g−1 and enhancement factors between 35 and 59, with appreciable analytical sensitivity.

Most of the official procedures aiming at classification of solid waste toxicity take into account metal solubility and bioavailability by means of extraction experiments using acetic acid solutions. Hence, the aim of this work was to investigate and optimize conditions to suppress the effect of acetic acid on the determination of trace elements using inductively coupled plasma mass spectrometry. The performance of four nebulizers (cross-flow (CFN), ultrasonic (USN), Meinhard (MN) and MicroMist (MMN)) were compared as to their efficiency in minimizing spectral and non-spectral effects on the determination of Ag, As, Ba, Cd, Cr, Hg, Pb and Se, with the ultimate goal to analyze acetic acid extracts obtained from solid waste residues. Operating conditions (desolvation temperatures for USN, RF power and nebulizer gas flow rates) were optimized individually for each nebulizer and for all analytes maintained in 0.14 mol L − 1 HNO 3 solutions and in solutions prepared with acetic acid and acetic acid + NaOH, adjusted to pH 2.88 and 4.93, respectively. Pronounced non-spectral interferences for 75 As and 82 Se were observed in the presence of acetic acid for CF and MN, although to a less extent also for MMN and USN. Signal increase for blank solutions measured at m/z 208 ( 208 Pb) for CFN and MN, 107 ( 107 Ag) for USN and MN coupled to a cyclonic chamber and, m/z 82 ( 82 Se) for USN was observed, indicating an increased risk of spectral interference upon an increase in the concentration of acetic acid. Signal increase at specific m/ z ratios, however, was not significant when the MMN was used, with the exception of m/z 52 ( 52 Cr) in acetic acid solutions, arising from the formation of 40 Ar 12 C + . This same effect was noticed for all nebulizers, although at noticeably different intensities. A signal stability study was performed, demonstrating that variations in the analytical signal were within a 20% range for all analytes, with the exception of Hg, after continuous aspiration for 70 min. The nebulization efficiency ranged from 4.6% to 64% for CF and MM nebulizers, respectively. Leaching solution from a solid waste residue was analyzed using all the studied systems in three different calibration media. In general, the results indicate that calibration solutions should be prepared in the same medium as the leachate, although for USN and MMN a reasonable agreement among the results was obtained regardless of the calibration solution used. Detection limits ranging from 0.01 μg L − 1 to 2 μg L − 1 were obtained, with little discrepancy among the different nebulizers used.

A procedure for the determination of Al, Cu, Fe and Mn in biodiesel samples by high resolution continuum source electrothermal atomic absorption spectrometry is proposed. Sample preparation consists in simply diluting the biodiesel samples with ethanol at room temperature. For Al determination, a Zr-treated graphite tube was used as permanent modifier; for the other analytes no modifier was required. Calibration was carried out against aqueous standards, except for Al, for which calibration solutions were prepared using ethanol. Accuracy was verified by means of recovery tests and comparison with the results obtained using a different analytical procedure. The precision, expressed as the relative standard deviation, was typically better than 7%. Detection limits at ng g−1 levels for all analytes were obtained. The concentration of the analytes in biodiesel samples was generally very low, around a few tens of ng g−1, except for two samples for which the Fe concentrations were in the μg g−1 level. The proposed method has proved to be simple, precise and accurate.

A study has been undertaken to assess the capability of high-resolution continuum source graphite furnace atomic absorption spectrometry for the determination of mercury in airborne particulate matter (APM) collected on glass fiber filters using direct solid sampling. The main Hg absorption line at 253.652 nm was used for all determinations. The certified reference material NIST SRM 1648 (Urban Particulate Matter) was used to check the accuracy of the method, and good agreement was obtained between published and determined values. The characteristic mass was 22 pg Hg. The limit of detection (3σ), based on ten atomizations of an unexposed filter, was 40 ng g− 1, corresponding to 0.12 ng m− 3 in the air for a typical air volume of 1440 m3 collected within 24 h. The limit of quantification was 150 ng g−1, equivalent to 0.41 ng m−3 in the air. The repeatability of measurements was better than 17% RSD (n = 5). Mercury concentrations found in filter samples loaded with APM collected in Buenos Aires, Argentina, were between

The simultaneous determination of Ni and V as their total and non-volatile fractions in crude oil samples using high-resolution continuum source graphite furnace atomic absorption spectrometry is p...

This work describes the method development for the simultaneous determination of Cd and Fe using the main resonance line of Cd at 228.802 nm and a secondary Fe line at 228.725 nm, and high-resolution continuum source electrothermal atomic absorption spectrometry (HR-CS ET AAS). Two certified reference materials and two ‘real’ samples of industrial and domestic sewage sludge have been analyzed as slurries prepared in a mixture of HF and HNO3. The simultaneous determination has been performed using a short temperature program of only 30 s, without a pyrolysis stage and with two atomization stages, at 1300 °C and 2300 °C, taking into consideration the significantly different thermal characteristics of Cd and Fe. Structured background, which is likely due to the presence of one or more diatomic molecules, including SiO, has been detected. However, there has been no spectral overlap between molecular bands and the atomic lines of Cd and Fe, making possible the determination to be carried out using only automatic correction for continuous background. Calibration against aqueous standards lead to good agreement between certified or informed values and the determined values, at a statistical confidence level of 95%; recovery tests were performed for real samples, resulting in recoveries ranging from 90 to 105%. Detection limits of 0.03 and 90 µg g− 1 for Cd and Fe, respectively, have been obtained, which are adequate for the purpose.

Reactivity and concentration of additives, especially activated charcoal, employed for the Lyocell process, enhance the complexity of reactions in cellulose/N-methylmorpholine-N-oxide monohydrate solutions. Analytical control of the starting materials is a basic requirement to know the concentration of heavy metals, which are potential initiators of autocatalytic reactions. Seven activated charcoal and two carbon black samples have been analyzed regarding their content of seven elements, Cr, Cu, Fe, Mn, Mo, Ni and V using direct solid sampling high-resolution continuum source graphite furnace AAS (SS-HR-CS GF AAS) and inductively coupled plasma optical emission spectrometry (ICP OES) after microwave-assisted acidic digestion as a reference method. The limits of detection of the former technique are 1-2 orders of magnitude lower than those of ICP OES and comparable to those of more sophisticated techniques. For iron the working range of HR-CS GF AAS has been expanded by simultaneous measurement at two secondary absorption lines (344,099nm and 344,399nm). Partial least-squares regression between measured and calculated temperatures for beginning exothermicity (T(on)) has been used to investigate the prediction capability of the investigated techniques. Whereas the ICP OES measurements for seven elements resulted in an error of prediction of 3.67%, the results obtained by SS-HR-CS GF AAS exhibited a correlation coefficient of 0.99 and an error of prediction of only 0.68%. Acceptable correlation has been obtained with the latter technique measuring only three to four elements.

This work describes the determination of silver in soil, sediment, rock and ore reference materials using direct solid sampling (SS) and high-resolution continuum source electrothermal atomic absorption spectrometry (HR-CS ET AAS). Pyrolysis and atomization temperatures were optimized as 800 °C and 1,900 °C, respectively, for soils and sediments, and calibration against aqueous standards resulted in good agreement between certified or informed and determined values at a 95% confidence level. The analysis of rocks and ores, however, required calibration against a solid certified reference rock sample, as in these materials the sulfur-rich matrix reduces the atomization efficiency. For these samples, background absorption with pronounced fine structure due to a sulfur-containing molecule has been detected, although with negligible influence on the analytical signal at the optimized atomization temperature of 2,300 °C. The application of a least-squares background correction algorithm resulted in a background-free spectrum. A detection limit (3s, n = 10) of 2 ng g−1 has been obtained. The proposed procedure has proved to be fast, sensitive and reliable for the analysis of geological samples using SS-HR-CS ET AAS.

The artifacts created in the measurement of phosphorus at the 213.6-nm non-resonance line by electrothermal atomic absorption spectrometry using line source atomic absorption spectrometry (LS AAS) and deuterium lamp background correction (D 2 BC) have been investigated using high-resolution continuum source atomic absorption spectrometry (HR-CS AAS). The absorbance signals and the analytical curves obtained by LS AAS without and with D 2 BC, and with HR-CS AAS without and with automatic correction for continuous background absorption, and also with least-squares background correction for molecular absorption with rotational fine structure were compared. The molecular absorption due to the suboxide PO that exhibits pronounced fine structure could not be corrected by the D 2 BC system, causing significant overcorrection. Among the investigated chemical modifiers, NaF, La, Pd and Pd + Ca, the Pd modifier resulted in the best agreement of the results obtained with LS AAS and HR-CS AAS. However, a 15% to 100% higher sensitivity, expressed as slope of the analytical curve, was obtained for LS AAS compared to HR-CS AAS, depending on the modifier. Although no final proof could be found, the most likely explanation is that this artifact is caused by a yet unidentified phosphorus species that causes a spectrally continuous absorption, which is corrected without problems by HR-CS AAS, but which is not recognized and corrected by the D 2 BC system of LS AAS.

Lead was extracted as the O,O-diethyldithiophosphate (DDTP) complex from aqueous solution into a drop of CHCl(3) immersed in the solution. Unlike previously reported procedures using single drop micro-extraction (SDME) for the extraction of inorganic analytes, the complexation reaction was conducted in the aqueous phase, as the ammonium salt of DDTP is soluble in water. The concentration of DDTP was optimized as 0.01% (m/v). Experimental parameters such as extraction time (7min) and organic drop volume (3microL) were optimized and selected as a compromise between sensitivity and stability of the organic drop in the aqueous solution. The sensitivity with electrothermal atomic absorption spectrometry (ET AAS) was low, probably due to infiltration of the organic drop into the totally pyrolytic graphite platform. To overcome this problem, tungsten (400microg) was thermally deposited onto the platform surface. A short pyrolysis stage at 700 degrees C was included to reduce background absorption. Under these conditions, five certified reference materials with different characteristics were analyzed using calibration against aqueous standards submitted to the SDME procedure, resulting in good agreement between certified and found concentration values at a 95% confidence level. Two real water samples have also been analyzed, with recoveries ranging from 85 to 92% after enrichment with Pb. An enhancement factor of 52 allowed a detection limit of 0.2microg L(-1) or 0.04microg g(-1), demonstrating the high detection capability of the proposed procedure, with a relative standard deviation typically below 4%.

In high-resolution continuum source atomic absorption spectrometry (HR-CS AAS) with a pixel detector, such as a charge-coupled device array for signal registration, the absorbance A not only depends on the absorption coefficient, the length of the absorbing layer and the number of absorbing atoms therein, but also on the spectral interval over which the signal is recorded, i.e., the spectral bandwidth per pixel and the number of pixels evaluated. Although the problem of different (absorption and emission) line widths is known for several decades already to exist in conventional line source AAS, it is usually disregarded. By choosing a certain number of pixels in HR-CS AAS a defined wavelength interval can be selected over which the absorbance is recorded. As the numerical values obtained this way are not directly comparable with the conventional absorbance, it is necessary to define new terms and symbols for this kind of signal evaluation. With a steady-state signal the individual pixel absorbance values can be added or integrated, resulting in the unit-free wavelength-selected absorbance (WSA, symbol A Σ ), or the wavelength-integrated absorbance (WIA, symbol A λ ) having a wavelength unit, such as picometers (pm). Similarly, with transient signals one can add-up or integrate (over wavelength) the individual integrated (in time) absorbance values of the selected pixels to obtain the volume under the absorbance peak. This results in the peak volume selected absorbance (PVSA, symbol A Σ,int ), and the peak volume integrated absorbance (PVIA, symbol A λ ,int ), with the units second (s) and second times picometer (s pm), respectively. For comparison purposes, however, the integrated absorbance values, i.e., WIA or PVIA, should be used since they are instrument-independent. Several elements with narrow and broad absorption lines and with multiplets, respectively, have been chosen to investigate the feasibility of using different signal registration schemes. Especially the evaluation of WSA and PVSA with respect to sensitivity, linearity of the calibration curves and limits of detection was focused on.

The literature about applications of high-resolution continuum source atomic absorption spectrometry (HR-CS AAS) with electrothermal atomization is reviewed. The historic development of HR-CS AAS is briefly summarized and the main advantages of this technique, mainly the ‘visibility’ of the spectral environment around the analytical line at high resolution and the unequaled simultaneous background correction are discussed. Simultaneous multielement CS AAS has been realized only in a very limited number of cases. The direct analysis of solid samples appears to have gained a lot from the special features of HR-CS AAS, and the examples from the literature suggest that calibration can be carried out against aqueous standards. Low-temperature losses of nickel and vanadyl porphyrins could be detected and avoided in the analysis of crude oil due to the superior background correction system. The visibility of the spectral environment around the analytical line revealed that the absorbance signal measured for phosphorus at the 213.6 nm non-resonance line without a modifier is mostly due to the PO molecule, and not to atomic phosphorus. The future possibility to apply high-resolution continuum source molecular absorption for the determination of non-metals is discussed.

Cloud point extraction (CPE) is proposed as a pre-concentration procedure for the determination of Pb and Cd in undigested urine by graphite furnace atomic absorption spectrometry (GF AAS). Aliquots of 0.5 mL urine were acidified with HCl and the chelating agent ammonium O , O -diethyl dithiophosphate (DDTP) was added along with the non-ionic surfactant Triton X-114 at the optimized concentrations. Phase separation was achieved by heating the mixture to 50 °C for 15 min. The surfactant-rich phase was analyzed by GF AAS, employing the optimized pyrolysis temperatures of 900 °C for Pb and 800 °C for Cd, using a graphite tube with a platform treated with 500 μg Ru as permanent modifier. The reagent concentrations for CPE (HCl, DDTP and Triton X-114) were optimized using a Box–Behnken design. The response surfaces and the optimum values were very similar for aqueous solutions and for the urine samples, demonstrating that aqueous standards submitted to CPE could be used for calibration. Detection limits of 40 and 2 ng L − 1 for Pb and Cd, respectively, were obtained along with an enhancement factor of 16 for both analytes. Three control urine samples were analyzed using this approach, and good agreement was obtained at a 95% statistical confidence level between the certified and determined values. Five real samples have also been analyzed before and after spiking with Pb and Cd, resulting in recoveries ranging from 97 to 118%.