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Worldwide, cosmetics (especially eye shadows) are widely consumed and have a great impact on the economy. The aim of this study was to determine the multielement composition, focusing on essential and potentially toxic elements, in cosmetics (eye shadow) exposed to consumption in Brazil. Concentrations of 17 elements (Al, As, Ba, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Sb, Se, Sr, Ti, V and Zn) were determined in samples (produced in China and Brazil) using a sequential optical emission spectrometer with inductively coupled plasma (ICP OES) after acid digestion, assisted by a closed digester block (6 mL of HNO

The objective of this study was to obtain optimized nanostructured lipid carriers (NLC) functionalized with chitosan containing chloroaluminum phthalocyanine (ClAlPc) as a photosensitizer. Initially, the optimization of the preparation method of the NLC was performed, where the influence of different surfactants such as PVA and Tween 80, as well as different solid lipids such as stearic acid and Glycerol Monostearate (GM) was evaluated. The formulation containing GM and PVA (NLC10) was considered promising. Following, by the adsorption method (NLC10q), the formulation was functionalized with chitosan and characterized. NLC10 and NLC10q presented sizes of 131.5 and 231.5 nm, and ZP of -24.30 and + 19.96 mV, respectively. The encapsulation efficiency of NLC10q was 96 %, higher than NLC10 (79 %). The formulations were able to promote significant cutaneous retention of ClAlPc, after 2 h and 4 h of the study, and showed to be non-toxic to fibroblasts (biocompatible). PDT in BF16-F10 melanoma resulted in reduced cell viability to 70 % and 50 % for NLC10 and NLCq, respectively. In view of the results obtained, NLC showed to be promising in the treatment of skin cancer through PDT. NLC10q showed higher encapsulation efficiency and stability than NLC10, but, contrary to what was expected, it presented lower photodynamic efficiency.

In this study, the use of hydride generation atomic fluorescence spectrometry (HG-AFS) coupled with the multi-syringe flow injection analysis (MSFIA) has been proposed in the application of the Doehlert design to optimise the determination of As and Sb in gouache and tempera children's paints. The determination of the total and bioavailable As and Sb in paint samples from various brands and colours was also investigated. The limits of quantification (LOQ) obtained for the determination of As and Sb were 14.0 and 8.6 ng g-1, respectively. The accuracy and precision of the method were evaluated through recovery tests (by the analyte addition method) at three levels for both elements, and by the analysis of certified reference materials of clay (CRM 052, Loamy Clay 1) and river water (SLRS-4). Twenty paint samples, manufactured in China, Italy, Spain and Brazil, were analysed. The concentrations of As varied between below LOQ (

In this work, a methodology for chemical speciation analysis of inorganic As and Sb in urban dust using slurry sampling and detection by fast sequential hydride generation atomic absorption spectrometry is proposed. Doehlert design and desirability function were used to find the optimum conditions for hydride generation (1.0 mol L−1 HCl and 0.9% m v−1 NaBH4). The accuracy of the analytical method was evaluated by analysis of reference material fly ash (BCR 176R), addition and recovery tests for inorganic As species, and comparison of independent methods for Sb determination in urban dust samples. The determination of the total concentrations of As and Sb and their inorganic species presented good accuracy, between 80 ± 1 and 101 ± 6%. Precision was expressed as the relative standard deviation and was better than 4.7% (n = 3). The limit-of-quantification values were 0.23 and 1.03 mg kg−1 for As and Sb, respectively. The methodology was applied to eight samples of dust collected in an urban area of Salvador and Jaguaquara cities, Bahia, Northeast, Brazil, with an aerodynamic size lower than 38 μm. Concentrations of pentavalent inorganic species (iAs5+ and iSb5+) in relation to trivalent species (iAs3+ and iSb3+) were found in urban dust collected in the city of Salvador, which are regarded as more toxic for both elements. The enrichment factor and geoaccumulation index (Igeo) values showed that for some samples, the concentrations of iAs and iSb presented strong enrichment and, and regarding environment, strong to moderately polluted by iAs and iSb, with an indication of anthropogenic contributions. The occurrence of these inorganic constituents in the urban area of Salvador can be related with intense industrial activities and vehicular traffic.

In this work the urban area of Aracaju city, located in the State of Sergipe, Northeastern Brazil was the site for simultaneous collection of suspended particles (TSP) and inhalable particulate matter (PM10) aiming an evaluation of the air quality parameters. Concentrations of Cd, Co, Cu, Fe, Mn, Ni, Pb and V in TSP and PM10 were determined by inductively coupled plasma mass spectrometry (ICP-MS). Iron was the most abundant element found in both particulate samples. Through chemometric tools, it was possible to point out that the contributions to the TSP and PM10 formation are similar, and strong correlations were observed between Fe-Mn (0.83) and Cd-Pb (0.93) in TSP, and Fe-Mn (0.90), Fe-Cu (0.81) and Cd-Pb (0.97) in PM10, an evidence that these species are from sources related mainly to soil resuspension and vehicular traffic. Enrichment factor (EF) and geoaccumulation index (Igeo) showed an influence of fossil fuel burning in the composition of TSP and PM10. Through principal component analysis (PCA) and hierarchical cluster analysis (HCA) it was observed particle size distribution groupings according to its aerodynamic size. Evaluation of the concentrations obtained for the collected samples according to the seasons (dry and rainy), indicated the influence of both, biogenic (resuspension of soil and marine aerosols) and anthropic (vehicle traffic and biomass burning) sources.

In this work, a procedure is proposed for the direct analysis of powdered refreshments by fast sequential flame atomic absorption spectrometry (FS-F AAS), after a simple treatment of the sample. A full 23 factorial design was applied, and the variables chosen were as follows: acid concentration, acid type, and sonication time. Optimization provided the best conditions considering a mass of powdered refreshment of about 0.18 g diluted to a final volume of 15 mL with 0.5 mol L−1 HCl. The matrix effect was investigated, and external calibration was feasible for the determination of Cd, Co, Cu, Fe, Mg, Mn, Ni, Pb, and Zn. The limit of quantification (LoQ) obtained was between 0.6 (Cd) and 25 mg kg−1 (Pb). The analyte addition and recovery test were applied to evaluate the accuracy, and recovery percentage values ranging from 83.9 to 109.7% were obtained, which is considered adequate for quantitative analysis. Precision was expressed as relative standard deviation (% RSD); it was less than or equal to 5.0% (n = 7) for all analytes. The procedure was applied to 21 samples of powdered refreshment commercialized in Salvador (Brazil) and Buenos Aires (Argentina). The concentration range and average of the analytes in the samples (in mg kg−1) commercialized in Brazil (BZ) and Argentina (AG) were as follows: Co (BZ

An analytical method for multi-elementary determination in powder refreshment, based on sample digestion using dilute mineral acids and detection by inductively plasma coupled optical emission spectrometry (ICP OES) is proposed. Chemometric tools, such as fractional factorial design and principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied to optimize the sample preparation conditions in closed block digester, and Doehlert design for spectrometer operation. Addition and recovery tests and analyses of certified reference material were performed to evaluate the precision and accuracy, and the results confirm the reliability of the proposed method. Limits of quantification (LOQ) between 0.02 and 36 μg g−1 were obtained. The analytical method was applied for determination of 24 inorganic constituents in 20 powder refreshment samples. Calcium, K, Mg, Na, P, S and Ti presented the highest concentrations. The analytical method was adequate for the determinations of inorganic constituents in powder refreshment samples by ICP OES.

Atmospheric pollution has been considered one of the most important topics in environmental science once it can be related to the incidence of respiratory diseases, climate change, and others. Knowing the composition of this complex and variable mixture of gases and particulate matter is crucial to understand the damages it causes, help establish limit levels, reduce emissions, and mitigate risks. In this work, the current scenario of the legislation and guideline values for indoor and outdoor atmospheric parameters will be reviewed, focusing on the inorganic and organic compositions of particulate matter and on biomonitoring. Considering the concentration level of the contaminants in air and the physical aspects (meteorological conditions) involved in the dispersion of these contaminants, different approaches for air sampling and analysis have been developed in recent years. Finally, this review presents the importance of data analysis, whose main objective is to transform analytical results into reliable information about the significance of anthropic activities in air pollution and its possible sources. This information is a useful tool to help the government implement actions against atmospheric air pollution.

In this work, the use of a multisyringe flow injection analysis coupled to hydride generation atomic fluorescence spectrometry (MSFIA-HG-AFS) for inorganic selenium chemical speciation was proposed. A Doehlert design was applied to optimize the experimental conditions for hydride generation (NaBH4 and HCl concentrations). The limits of quantification (LoQ) obtained were 0.07 µg L−1, for total inorganic Se, and 0.08 µg L−1, for Se(IV). Accuracy and precision of the proposed analytical method were evaluated through analysis of standard reference material and addition and recovery tests. The optimized method was applied to analyses of eight samples of beer, produced in Spain, obtaining concentrations for Se(IV) (

An acid digestion procedure of the forage palm (Opuntia ficus-indica Mill and Nopalea cochenilifera) employing a closed digestor block applied full 24 factorial design was optimized. The optimal conditions were HNO3 5.0 mol L−1, 2.0 mL of H2O2 30% m m−1, 120 min of digestion, and heating temperature of 180 °C. The certified reference materials of apple leaves (NIST 1515) and tomato leaves (Agro C1003a) were used to evaluate the accuracy of the analytical method. The concentrations of the macroelements were (in % m m−1) Ca (1.32–3.71), K (0.88–5.29), Mg (0.70–1.78), and P (0.03–0.32). For the microelements, the concentrations (in μg g−1) obtained were As (

This work describes the application of an experimental design in optimizing the decomposition and spectrometer operational conditions for analysis of fish feeds. The content of 22 elements (six macroelements, four microelements and eleven trace elements) in feeds for fishes (ornamental and for human consumption) was determined by inductively coupled plasma (ICP)-based methods. Limits of quantification were obtained and the values ranged between 0.02 mg kg−1 (Cd) and 76 mg kg−1 (Al). Evaluation of the methods was achieved through analysis of standard reference material, Oyster Tissue (NIST 1566b) and Tea (NCS DC 73351). Element concentrations in feed samples for ornamental fish ranged from

Four species of bivalve molluscs (Anomalocardia brasiliana, Iphigenia brasiliana, Lucina pectinata and Trachycardium muricatum) were collected in the Todos os Santos Bay (TSB), Bahia, Brazil, in order to evaluate As, Cd, Co, Cu, Cr, Fe, Mn, Ni, Pb, Se, V and Zn levels and, consequently, the risk of bivalve mollusc consumption in humans. The samples were analyzed by inductively coupled plasma optical emission spectrometry (ICP OES) and inductively coupled plasma mass spectrometry (ICP-MS) after closed-vessel microwave digestion. The accuracy was confirmed using the certified reference materials of oyster tissue (NIST 1566b) and mussel tissue (NIST 2977), and the results were statistically equivalent to the certified values. Application of principal component analysis (PCA) and hierarchical cluster analysis (HCA) showed a tendency to form two groups between samples of Lucina pectinata and Trachycardium muricatum. All species showed As and Cr concentrations higher than the maximum tolerable limit specified in Brazilian legislation.

Carbon-supported platinum is used as an anode and cathode electrocatalyst in low-temperature fuel cells fueled with low-molecular-weight alcohols in fuel cells. The cost of Pt and its low activity towards the complete oxidation of these fuels are significant barriers to the widespread use of these types of fuel cells. Here, we report on the development of PtRhNi nanocatalysts supported on carbon made using a reduction chemistry method with different atomic rates. The catalytic activity of the developed catalysts towards the electro-oxidation of methanol, ethanol, ethylene glycol, and glycerol in acidic media was studied. The obtained catalysts performances were compared with both commercial Pt/C and binary Pt75Ni25/C catalyst. The nanostructures were characterized, employing inductively coupled plasma optical emission spectrometer, X-ray diffraction, scanning transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The binary catalyst presents a mean particle size of around 2 nm. Whereas the ternary catalysts present particles of similar size and with some large alloy and core–shell structures. The alcohol oxidation onset potential and the current density measured after 3600 s of chronoamperometry were used to classify the catalytic activity of the catalysts towards the oxidation of methanol, ethanol, ethylene glycol, and glycerol. The best PtRhNi/C catalyst composition (i.e., Pt43Rh43Ni14/C) presented the highest activity for alcohols oxidation compared with all catalysts studied, indicating the proper tuning composition influence in the catalytic activity. The enhanced activity of Pt43Rh43Ni14/C can be attributed to the synergic effect of trimetallic compounds, Pt, Ni, and Rh.

In this work, the concentration of Ca, K, Mg, Na, and Zn in milk samples (powder and liquid), milk compound and yogurt were determined, employing inductively coupled plasma optical emission spectrometry (ICP OES). Sample treatment was carried out in a microwave-assisted digester using the proportion of dilute HNO3 and H2O2 established through a two-level factorial design. Accuracy and precision of the method were confirmed through analysis of certified reference materials of Non-fat milk powder (NIST 1549) and Whole egg powder (NIST 8415). The agreement between found and certified values varied between 85 ± 10% for K and 116 ± 3% for Ca. Precision was expressed as relative standard deviation (%RSD), being below than 5.0%, for all elements. Samples of bovine skimmed milk powder contained higher levels of Ca (12,575 mg kg−1) and Na (4670 mg kg−1), while whole goat milk powder presented highest concentrations of K (13,550 mg kg−1) and Mg (1245 mg kg−1), and milk compounds higher content of Zn (31.0 mg kg−1). Plain yogurt samples, when compared with flavored yogurts, presented greater levels of all elements: Ca (1438 mg kg−1), K (1,345 mg kg−1), Mg (133 mg kg−1), Na (988 mg kg−1) and Zn (6.00 mg kg−1). Principal component analysis (PCA) and hierarchical cluster analysis (HCA) allowed the discrimination of milk powder samples from liquid milk and yogurt samples, through the concentrations of Ca, K, Mg, Na, and Zn, and liquid milk and yogurt samples presented lower concentrations of these elements. The yogurt samples were differentiated from the liquid milk samples due to the Zn contents. Concentrations of Zn, found in all samples, were in agreement with Brazilian current legislation (

Three spectrophotometric methods were developed for the determination of copper (Cu) in sugar cane spirit using the chromogenic reagents neocuproine, cuprizone, and bathocuproine. Experimental conditions, such as reagent concentration, reducer concentration, pH, buffer concentration, the order of addition of reagents, and the stability of the complexes, were optimized. The work range was established from 1.0 to 10.0 µg/mL, with correlation coefficients of >0.999 for all three optimized methods. The methods were evaluated regarding accuracy by addition and recovery tests at five concentration levels, and the obtained recoveries ranged from 91 to 105% (n = 3). Precision was expressed as RSD (relative standard deviation), with values ranging from 0.01 to 0.17% (n = 10). The method using the chromogenic reagent cuprizone presented the greatest molar absorptivity, followed by bathocuproine and neocuproine. The methods were applied for the determination of Cu in sugar cane spirit, and the results were compared with a reference method by flame atomic absorption spectrometry (FAAS). Calibration curve solutions for FAAS analysis were prepared in a 40% (v/v) alcohol medium in a range of concentrations from 0.5 up to 5 µg/mL. Measurements for Cu determination were carried out at a wavelength of 324.7 nm. The concentrations obtained for Cu in sugar cane spirit samples from Brazil were between 1.99 and 12.63 µg/mL, and about 75% of the samples presented Cu concentrations above the limit established by Brazilian legislation (5.0 µg/mL or 5.0 mg/L).

Given the importance of knowing the real nutritional value of food, the main objective of this study was to evaluate the total elements concentrations and bioaccessibility of Ca, Cu, Fe, K, Mg, Mn, Mo, Na, P and Zn in linseed and sesame samples. A full 24 factorial design was applied to optimize the microwave assisted acid digestion of the samples. Total elements concentrations were obtained by inductively coupled plasma optical emission spectrometry (ICP OES). Extraction procedures were performed using the Unified Bioaccessibility Method (UBM) to evaluate the bioaccessibility. The highest total content, in μg g− 1, were observed for K (4526–9768), P (3418–7014) and Mg (2527–4633), whereas Mo (

In this work, microwave-assisted digestion sample treatment and two ICP-based method operational conditions were optimized to determine 17 elements in cassava, corn and wheat flours using experimental design. The proposed analytical methods showed acceptable sensitivity, with limits of quantification for Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Ni, P, S, Sb, Sr and Zn ranging from 0.02 μg g − 1 (Cd, Co and Sb) up to 0.002% (S) employing inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP OES). The accuracy of the analytical methods was confirmed by analysis of certified reference materials of rice flour (NIST 1568a), wheat flour (NIST 1567a) and Tea (NCS DC 73351), with agreement between 82 ± 3% (Cr) and 108 ± 10% (Fe). Precision was expressed as relative standard deviation (RSD) and the found values were lower than 9% (Fe, n = 3) for all elements, except for Cd by ICP-MS, whose RSD value was 14%. The proposed methods were then used to determine the mineral composition of 37 samples of cassava, corn and wheat flours bought in commercial establishments in Aracaju city, Sergipe State, Brazil. The Ca, K, P, Mg and S concentrations ranged from 2.72 ± 1.09 μg g − 1 for Ca up to 4253 ± 103 μg g − 1 for K. The concentrations of the microelements and trace elements, such as Ba, Cd, Co, Cu, Fe, Mn, Sr and Zn, varied between − 1 for Sr up to 65.5 ± 9.7 μg g − 1 for Fe. Cassava, corn and wheat flours were subsequently characterized through multivariate data analysis (principal component analysis and hierarchical cluster analysis). Three distinct groups of flour were observed according to the elemental compositions.

In this work, studies using samples collected in an urban area of Aracaju city, Sergipe State, Northeast, Brazil revealed that soil dust in suspension was the main source of total airborne particulate matter (TAPM), followed by vehicular pollution. The concentration profiles for Cu, Fe, Mn, Ni, V and Ti were established for the collected TAPM samples. The concentrations of SO2 and smoke were also measured all along the 42 sampling days. Through multivariate data analysis of the results a correlation between Fe, Mn, Ni and Ti in the mineral composition of the particles was established, indicating soil dust in suspension as the main source of TAPM. The concentrations of Cu and smoke were found to be related to vehicular traffic, and the second largest source of TAPM. Enrichment factors (EF) were calculated for the studied elements, and only Cu was found to be enriched. The concentrations of the elements in TAPM were evaluated using the geoaccumulation index (Igeo), and Fe, Mn, Ni, V and Ti were found to derive from natural sources, in TAPM. However, approximately 55% of the samples did not presented Cu contamination (Igeo≤0), and the remaining 45% presented Cu concentrations levels that indicated between low to moderate (0

In this work, an analytical method for determination of Ba, Cu, Ni, V, and Zn, in medicinal herbs, through direct solid sample analysis by energy dispersive X-ray fluorescence spectrometry (EDXRF), was applied. Accuracy and precision (intra and inter day) of the analytical method were confirmed through analysis of certified reference material, tomato leaves (CRM NIST 1573a). Principal component analysis (PCA) and hierarchical cluster analysis (HCA) allowed to observe the formation of two groups. Group I was composed by highest levels of Cu and Zn, and the group II with highest concentrations of Ba, V, and Zn. Group I also was subdivided into two subgroups. The concentration of Ni in some samples exceeded the maximum allowed limit. In all samples, Cu and Zn concentration were below the maximum limit allowed by Brazilian legislation. However, for Ba and V, the evaluation was not possible, because there are no maximum limits in legislation.

Corn is one of the most consumed cereals in world and the second most cultivated in Brazil. Cereal flour has a flavor well accepted by the Brazilian population. This work describes the preparation and characterization of a new corn flour reference material which can be used as a quality assurance tool to demonstrate the reliability of the analytical results obtained from inorganic analysis of cereals and their derivatives. The studied elements were Ca, K, Mg, P, Cu, Fe, Mn and Zn. Homogeneity and stability tests, material characterization and attribution of uncertainty value were performed in this work by following recommendations of ISO Guides 30–35. The material was shown to be homogeneous and stable for 15 months at temperatures of −10 °C, +25 °C and +45 °C, with small uncertainty. Alternatively, the data were analyzed by hierarchical clustering technique and the stability was confirmed. The confidence ellipse technique enabled a simple and fast evaluation of data supplied by collaborating laboratories allowing the exclusion of outlying values and indicating possible causes of the deviations.

This work describes an analytical method for Zn determination in dry feeds for cats and dogs by energy-dispersive X-ray fluorescence (EDXRF). Samples of dry feed were powdered and prepared in the form of pellets for direct analysis by EDXRF. The LOQ (10σ) was 0.4 mg/kg. The samples were also analyzed by inductively coupled plasma-optical emission spectrometry (ICP-OES) as an independent comparative method. Application of a paired t-test showed no significant differences between Zn concentrations obtained by EDXRF and ICP-OES (at a 95% confidence level). Analysis of variance was also applied to the results and revealed no significant differences between the two techniques (at a 95% confidence level). The precision, expressed as the RSD (n = 3), was RSD < 4.55%. This analytical method provides a simple, rapid, accurate, and precise determination of Zn in dry feeds for cats and dogs by EDXRF as direct, solid-sample analysis.

Rare earth elements (REEs) are essential in high technology industries and have great economic value. The monitoring of REEs concentrations in rocks from oil well drill cuttings is critical to avoid environmental contamination and evaluate new sources of these elements. However, information is scarce about the REEs concentrations in drill cuttings. In this work, the concentration of REEs in drill cuttings from oil and gas exploration wells in ultradeep coastal water of Brazilian were investigated at different depths. The drill cutting samples were submitted to microwave-assisted acid digestion prior to the determination of concentration by ICP-MS, using Rh as internal standard for calibration. The limits of quantification (LoQ) ranged from 3.3 μg kg−1 for Ho to 198 μg kg−1 for Sm. The accuracy was evaluated by analyzing certified reference materials for rocks. The obtained REEs concentrations agreed with the certified values, reaching 83%–105% agreement. The drill cutting depth profile analysis indicates Ce, La, Nd, Sm, and Eu concentrations up to mg kg−1. The REEs concentrations obtained in drill cutting depth profile was analyzed by principal component analysis (PCA), and hierarchical cluster analysis (HCA) identified tendency and similarity between drill cutting samples. Three groups were formed according to the composition of the REEs. In addition, the concentration of these chemicals elements varied at different depths. The analysis of drill cuttings revealed REEs concentrations up to the mg per kg-range (ppm), potentially making this disposable material an alternative source for REEs extraction, and adding value to this material.

Oil-producing rocks can be characterized by organic, inorganic and palynological geochemical parameters to assess the quantity and quality of organic matter. In the present study, samples of source rocks collected from different formations (Fm) from the sedimentary basins of the Parnaiba (Pimentairas Formation) and Parana (Irati and Ponta Grossa Formations) were evaluated through the geochemical correlation between the types of organic matter and their different depositional paleoenvironments using chemometric tools. Among the inorganic geochemical parameters used in this evaluation are the concentrations and the diagnostic ratios between the transition elements (Co, Ni, V, and Mo) and internal transition (lanthanides and U). The analysis of the transition and internal transition elements were performed by ICP OES (Ni and V) and ICP MS (Co, Mo, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Tm, Yb, Lu, and U). The organic geochemical parameters selected for the characterization of the quantity and quality of the organic matter present in the samples of source rocks involved the determination of their total carbon content (%TOC) and sulfur (%TS), of the potential generator (S2) the amount of hydrocarbons produced by Rock-Eval pyrolysis and the calculation of the hydrogen (HI) and oxygen (OI) indexes. To compose the matrix of the multivariate analysis (PCA), were used ratios Ni/Co, V/Ni, U/Mo, V/V + Ni, TOC/TS the values of S2, HI, OI and the sum of rare earth elements (REE). The kerogen type, obtained through the HI and OI data, were also included in the matrix, information on the origin of the organic matter, and on the type of depositional paleoenvironment of each sample, obtained from previous works. It was observed the formation of three groups of data characterizing the formations Irati, Ponta Grossa and Pimenteiras according to the type of kerogen and organic matter, and also of its depositional paleoenvironment, showing that the exploratory data analysis allows the obtaining of rapid and efficient information on the chemical similarity between the complex samples from each formation.

In this work, the determination of ytterbium in road dust samples, employing a simple and fast methodology, based on sample preparation as slurry and analysis by high resolution-continuum source graphite furnace atomic absorption spectrometry (HR-CS-GFAAS), is purposed. The determinations were carried out on the Yb main line, 398.799 nm, using an integration time of 5.0 s. The optimum condition for the slurry preparation of road dust samples was established through a Doehlert matrix for two variables, which employed a HNO3 concentration of 0.24 mol L−1 and homogenization time of 34 min, using ultrasonic bath. The temperatures applied to the graphite furnace were optimized, wherein the pyrolysis and atomization temperatures were 1200 °C and 2700 °C, respectively, using 250 μg of W as permanent chemical modifier. To investigate possible matrix interferences in the determination of Yb in road dust samples, external calibration and standard addition curves were compared. The comparison between slopes of the external and standard addition calibration curves showed difference of about 7.0%, an indication of absence of matrix effects for determination of Yb in road dust samples. The limit of detection (LOD) and limit of quantification (LOQ) were 22 and 72 ng g−1, respectively, with a characteristic mass of 6.0 pg. The accuracy was confirmed through analyses of three certified reference materials (CRM): Trace Elements in Soil Containing Lead From Paint (NIST 2586), Rock (NCS DC 73301) and Geochemical Soil (TILL-1), and the good agreement between the found and certified values was obtained, 99 ± 4 to 104 ± 2%, corroborating the accuracy of the analytical method. The precision was expressed as relative standard deviation (RSD) for measurements in triplicate, being lower than or equal to 10.0%. The analytical method was used for Yb determination in eight samples of dust collected in an urban area of Salvador and Jaguaquara, Bahia State, Northeast, Brazil. The concentrations obtained for Yb ranged from 172 ± 13 to 2065 ± 122 ng g−1. Thus, the proposed analytical method presents the characteristics of being fast, precise and accurate for the determination of Yb in road dust samples, employing slurry sampling and detection by HR-CS-GFAAS.

In this work, fast sequential determination and chemical speciation analysis of inorganic arsenic and antimony in airborne particulate matter collected in outdoor and indoor environments using slurry sampling and detection by hydride generation atomic absorption spectrometry (HG-AAS) is proposed. A Doehlert design was applied to optimise the hydride generation conditions of As and Sb for fast sequential determination in the same aliquot of particulate matter samples after preparation of the slurry. The limits of quantification (LoQ) obtained for As and Sb were 0.3 and 0.9 ng m-3, respectively. The accuracy of the analytical method was confirmed by analysis of the certified reference material of urban particulate matter (SRM NIST 1648a), presenting concordance with certified values of 92.7±7.7% for As and 91.2±9.5% for Sb. Precision was expressed as relative standard deviation (% RSD, n=3), with our results presenting values better than 3.4% and 4.2% for total inorganic As and Sb, respectively. For all analysed samples, total As concentrations and its inorganic species were below the LoQ of the analytical method (

Eight petroleum samples from Potiguar Basin were submitted for determination of saturated biomarkers by gas chromatography (fingerprint), liquid chromatography (saturates, aromatics, resins and asphaltenes), gas chromatography-mass spectrometry (GC-MS), nickel and vanadium by high resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). The geochemical parameters provided information on type of depositional paleoenvironment in which organic matter that gave rise to each oil sample and level of thermal maturation reached by generating rocks that make up the Potiguar Basin were deposited. The relationships between the stable isotopes of carbon (δ13C) and between Ni and V concentrations of each petroleum sample were also evaluated. The evaluations separated for oil samples into two distinct groups. Group 1 formed by samples P1, P2, P5 and P8, with characteristics of generating rock that was deposited in a marine hypersaline environment. Group 2 composed of samples P3, P4, P6 and P7 with freshwater lacustrine depositional paleoenvironment, which were elucidated through the geochemical parameters studied. The hierarchical cluster analysis was presented as promising chemometric tool for characterization of petroleum samples in the according to their origin of the generating rock by ratio parameters of hopane/sterane , tetracyclic polyiprenoids/diastereomers and diastereos R+S/cholestane R+S.

The present study proposes the determination of copper and mercury in phosphate fertilizers by direct solid sampling analysis (SS) employing high resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). For Cu determination, two analytical lines were used: 327.3960 nm and 249.2146 nm. Hg determination was carried out on the line 253.6521 nm and 100 μg KMnO 4 was used as chemical modifier. The optimal pyrolysis temperature for Cu determination was 1300 °C. Atomization temperatures for Cu and Hg were 2400 and 1100 °C, respectively. External calibration with aqueous standard solutions was adopted for both elements. The limits of quantification (LoQs) and characteristic mass (m 0 ) obtained for Cu determination were 0.4 μg g − 1 and 1.12 ng, respectively, on line 249.2146 nm, and 64 μg g − 1 and 25 pg on 327.3960 nm. For mercury, LoQ and m 0 were 4.8 ng g − 1 and 39 pg, respectively. The accuracy of the proposed methods was confirmed by the analysis of standard reference material (SRM) of Trace Elements in Multi-Nutrient Fertilizer (SRM NIST 695). The precision expressed as relative standard deviation (RSD), was better than 8.2% for Hg and 7.7% for the Cu (n = 5), considered satisfactory for microanalysis in solid sample. Four fertilizer samples acquired in commercial establishments in the city of Salvador, Bahia, Brazil, were analyzed. The optimized analytical methods were simple, fast, accurate, precise and free of spectral interferences for the determination of Cu and Hg in phosphate fertilizer samples by SS–HR-CS GF AAS, avoiding the dissolution of the sample, the use of harmful reagents and the generation of residues.

The importance of the Carmopolis field in Brazil for the exploration of onshore crude oil dates back to 1963. Currently still in operation, this is a major field, serving as a model for enhanced oil recovery tests. In this field, the differences in the physicochemical characteristics have awakened an interest in understanding the implications of the chemical composition of crude oils. Four blends of crude oil from this field were characterized using the SARA (saturates, aromatics, resins and asphaltenes) method and advanced methods such as energy dispersive X-ray fluorescence spectroscopy (EDX), laser desorption/ionization mass spectrometry (LDI-MS), infrared (IR), ultraviolet (UV), and thermogravimetric (TG) analysis. Of the four blends investigated, CEOL3 had the greatest affinity for water. The results for the SARA analysis did not reveal significant differences between the blends. The analysis of CEOL3 asphaltenes by IR spectroscopy revealed greater O–H stretching associated with water, and the TG ind...

This work proposes the application of a Doehlert design to optimize dilute HNO3 and H2O2 concentrations employed for the digestion of samples of modelling clay for children (used as toy). Inductively coupled plasma-based (ICP) methods were employed to determine 22 inorganic constituents (Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, S, Sb, Se, Sr, V and Zn) in children's modelling clay samples. The limits of quantification (LoQ) obtained were between 0.003 mg kg-1 (Cd, Co and Sb) and 0.54 g kg-1(Ca) employing ICP-based methods. The accuracy and precision of the methods were evaluated by analysing the certified reference materials (CRMs) oyster tissue (NIST 1566b), rice flour (NIST 1568b), peach leaves (NIST 1547) and tomato leaves (NIST 1573a), along with addition and recovery tests. The children's modelling clay samples presented concentrations of As, Ba, Cd, Cr, Pb, Sb and Se in agreement with the maximum values established by National Institute of Metrology, Quality and Technology (Instituto Nacional de Metrologia, Qualidade e Tecnologia - INMETRO). However, for other elements it were obtained concentrations within the following ranges: Al (0.83 ± 0.12–2.91 ± 0.04 g kg−1), Ca (16.09 ± 0.20–24.56 ± 1.00 g kg−1), Cu (

In this work, an analytical method for the determination of Cd and Pb in natural coconut water samples, industrialized coconut water samples and coconut milk using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS), after minimum treatment of the sample was developed. The analytical method was applied to 46 samples collected in Salvador, Bahia (Brazil). The ranges of concentrations obtained were: 0.42–18.72 μg L−1 Cd and

Submitted by Gisele Mara Hadlich (gisele@ufba.br) on 2018-10-02T18:09:12Z No. of bitstreams: 1 1-s2.0-S0039914017310494-main.pdf: 301332 bytes, checksum: c47f41a8de22952ea1b705b044d9b6db (MD5) Approved for entry into archive by Jessica Alves (alves.jessica@ufba.br) on 2018-10-04T15:09:57Z (GMT) No. of bitstreams: 1 1-s2.0-S0039914017310494-main.pdf: 301332 bytes, checksum: c47f41a8de22952ea1b705b044d9b6db (MD5) Made available in DSpace on 2018-10-04T15:09:57Z (GMT). No. of bitstreams: 1 1-s2.0-S0039914017310494-main.pdf: 301332 bytes, checksum: c47f41a8de22952ea1b705b044d9b6db (MD5) Previous issue date: 2018 This work presents the optimization of a sample preparation procedure using microwave-assisted digestion for the determination of nickel and vanadium in crude oil employing inductively coupled plasma optical emission spectrometry (ICP OES). The optimization step was performed utilizing a two-level full factorial design involving the following factors: concentrated nitric acid and hydrogen peroxide volumes, and microwave-assisted digestion temperature. Nickel and vanadium concentrations were used as responses. Additionally, a multiple response based on the normalization of the concentrations by the highest values was built to establish a compromise condition between the two analytes. A Doehlert matrix optimized the instrumental conditions of the ICP OE spectrometer. In this design, the plasma robustness was used as chemometric response. The experiments were performed using a digested oil sample solution doped with magnesium(II) ions, as well as a standard magnesium solution. The optimized method allows for the determination of nickel and vanadium with quantification limits of 0.79 and 0.20 μg g−1 , respectively, for a digested sample mass of 0.1 g. The precision (expressed as relative standard deviations) was determined using five replicates of two oil samples and the results obtained were 1.63% and 3.67% for nickel and 0.42% and 4.64% for vanadium. Bismuth and yttrium were also tested as internal standards, and the results demonstrate that yttrium allows for a better precision for the method. The accuracy was confirmed by the analysis of the certified reference material trace element in fuel oil (CRM NIST 1634c). The proposed method was applied for the determination of nickel and vanadium in five crude oil samples from Brazilian Basins. The metal concentrations found varied from 7.30 to 33.21 μg g−1 for nickel and from 0.63 to 19.42 μg g−1 for vanadium. Talanta

Cat and dog feed production has increased worldwide, and much emphasis has been placed on the importance of determining the mineral composition of pet foods. In this work, the concentrations of Al, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Ni, P, Sr, V and Zn in dry feed for cats and dogs employing inductively coupled plasma-optical emission spectrometry (ICP OES) were determined and evaluated according to regulatory agencies. Forty-one dry feed samples (24 dog feed and 17 cat feed) were analyzed. The obtained concentrations ranged from 2.3 mg kg-1 (Ba) to 2.8 g kg-1 (Ca) in cat feeds, and from 3.8 mg kg-1 (Cu) to 3.4 g kg-1 (Ca) in dog feeds. The concentrations of P are in accordance with the Brazilian legislation, and Mn and Zn contents met the American legislation. The concentration values of Cu, K and Mg presented in some samples were below the limits established by American regulatory agency. Based on multivariate data analysis evaluated from flavors of the products and brands, it was concluded that the feed samples were uniform since there was no trend to group formation and classification according to their mineral composition, except one dog feed brand, which had a significant content of Al and Cu.

The fractional factorial and Doehlert designs for optimization of a slurry sampling procedure to determine of nutrients in sugarcane juice by inductively coupled plasma optical emission spectrometry (ICP OES) were applied. External calibration curves were used for direct analysis of the slurry. This procedure allowed determination of Ca, Cu, Fe, K and Mg with limits of detection (LoD) obtained of 2.0, 0.04, 0.2, 1.0 and 1.5 mg L−1, respectively. The precision was expressed as relative standard deviation (%RSD), being better than 1.4% (n = 3). Accuracy was confirmed by comparison with sample digestion method. The results for analysis of fourteen sugarcane juices samples demonstrated that the nutrients Ca, Cu, Fe, K and Mg have average contents of 108, 0.506, 6.40, 470 and 114 mg L−1, respectively. The proposed analytical method is a good alternative for simultaneous determination of nutrients in sugarcane juice using introduction of slurries and detection by ICP OES.

A full 24 factorial design was applied to find the best combination of diluted reagents (HNO3 and H2O2), time, and temperature for the digestion of samples of wet feed for dogs and cats using a closed digestion block. The residual carbon concentration (RCC) was used as the response in the factorial design. All variables and their interactions significantly influenced the digestion of the feed samples, as indicated by the RCC. The conditions established for the digestion of 0.05 g (dry mass) wet feed samples were the addition of 3.0 mol/L HNO3 and 5.0% m/m H2O2 in a final volume of 10 mL, followed by heating in a closed digestion block at a temperature of 170°C for 120 min. Analyses were performed by inductively coupled plasma (ICP) optical emission spectrometry (OES). LOQs ranged from 0.2 μg/g (Mg and Sr) to 51 μg/g (P). Accuracy of the analytical method was confirmed through the analysis of the Standard Reference Materials Tomato Leaves (NIST 1573), Apple Leaves (NIST 1515), and Peach Leaves (NIST 1547). The agreement values achieved ranged from 80.2 ± 0.3% for Ba to 113.8 ± 7.1% for Zn (n = 3). Addition and recovery tests were carried out by addingthe analytes to a feed sample at two concentration levels, and the recoveries were between 84 ± 6and 114 ± 10% for macroelements (Ca, K, Mg, and P; n = 3) and between 88 ± 3 and 113 ± 7% for microelements and trace elements (B, Cu, Fe, Sr, and Zn; n = 3). The precision values achieved for the different elements, expressed as RSDs, were better than 7.3%(Zn; n = 3) except for Cu determination, that was 14.6% (n=3). The optimized analyticalmethod was applied to 10 commercial samples of wet feed for cats and dogs, with the concentrations of Al, B, Ba, Ca, Cu, Fe, K, Mg, Mn, P, Sr, and Zn determined by ICP-OES.

This paper describes a method development for chlorine determination through the formation of MgCl molecule, applied for the first time for Cl quantification, by high resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS) in environmental samples. Pyrolysis and vaporization temperatures were optimized as well as the use of chemical modifier. Determinations were carried out at the wavelength of 377.010 and the compromise conditions of the graphite furnace temperature program were 500 °C and 2500 °C for pyrolysis and vaporization, respectively, using 10 µg of chemical modifier Pd. The concentration of reactants for the generation of MgCl molecule was optimized through Box-Behnken experimental design, using MgCl2 solution as source of chlorine. The optimum values according to the surface response were 5 g L−1 Mg, 25 mg L−1 of chlorine and 2% v v−1 of HNO3, condition in which the amount of Mg is at least 200 times higher than that of chloride. This excess of the forming agent ensures the complete formation of MgCl molecular species, since Cl is the limiting reactant. Certified reference materials, BCR 182 and NIST 8414, and addition and recovery tests were used to evaluate the accuracy of the method and good results were achieved at a 95% confidence level. The method was applied to direct determination of Cl in five produced water samples from offshore oil wellbore, high complex matrix, whose conventional methods require tedious treatment before the analysis.

An analytical method for simultaneous determination of macronutrients (Ca, Mg, Na and P), micronutrients (Cu, Fe, Mn and Zn) and trace elements (Al, As, Cd, Pb and V) in mineral fertilizers was optimized. Two-level full factorial design was applied to evaluate the optimal proportions of reagents used in the sample digestion on hot plate. A Doehlert design for two variables was used to evaluate the operating conditions of the inductively coupled plasma optical emission spectrometer in order to accomplish the simultaneous determination of the analyte concentrations. The limits of quantification (LOQs) ranged from 2.0 mg kg − 1 for Mn to 77.3 mg kg − 1 for P. The accuracy and precision of the proposed method were evaluated by analysis of standard reference materials (SRMs) of Western phosphate rock (NIST 694), Florida phosphate rock (NIST 120C) and Trace elements in multi-nutrient fertilizer (NIST 695), considered to be adequate for simultaneous determination. Twenty-one samples of mineral fertilizers collected in Sergipe State, Brazil, were analyzed. For all samples, the As, Ca, Cd and Pb concentrations were below the LOQ values of the analytical method. For As, Cd and Pb the obtained LOQ values were below the maximum limit allowed by the Brazilian Ministry of Agriculture, Livestock and Food Supply (Ministerio da Agricultura, Pecuaria e Abastecimento — MAPA). The optimized method presented good accuracy and was effectively applied to quantitative simultaneous determination of the analytes in mineral fertilizers by inductively coupled plasma optical emission spectrometry (ICP OES).

In this work, the evaluation of the mineral profile and estimation of the bioaccessibility of essential and potentially toxic elements in honey samples was proposed. The experimental design and multivariate data analysis were applied as tool chemometrics. The acidic honey decomposition procedure using a cold finger digester block was proposed for analysis by inductively coupled plasma optical emission spectrometry (ICP OES). The analytical method presented good precision (

In this work, experimental design methodologies for the optimisation of analytical methods for the determination of inorganic constituents in tobacco products (cigar, shredded and rope) employing inductively coupled plasm optical emission spectrometry. Box-Behnken design was applied to optimise the digestion procedure of tobacco product samples using a closed digester block. The sample preparation was used dilute nitric acid, suitable for the concept of Green Chemistry. The operating conditions of spectrometer were optimised applying Doehlert design. The limits of quantification (LoQ) varied between 0.09 μg g−1 (Ba and Ti) and 116 μg g−1 (Na). The accuracy was confirmed by analysis of the certified reference materials (CRM) of oriental tobacco leaves (CTA-OTL-1), apple leaves (NIST 1515) and tomato leaves (CRM-Agro C1003a). The analytical method was applied for the determination of nineteen elements (Al, As, Ba, Ca, Cd, Co, Cu, Fe, K, Mg, Mn, Na, Ni, P, S, Sr, Ti, V and Zn) in tobacco products samples (cigar, shredded and rope). The results showed that the mean concentrations of macroelements were higher in cigar samples, the exception being Na concentration, which was higher for rope tobacco. For all samples, K concentration was the highest observed, since it is the nutrient most readily absorbed by the plant. Regarding the microelements and trace elements, cigar samples had higher contents of the six metals (Zn > Ba > Ti > Ni > Co > Cd) than did shredded or rope tobacco. The shredded tobacco samples presented higher concentration of Fe and for rope tobacco, the higher concentrations were for Al > Mn > Cu. In addition, principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied to discriminate the different tobacco products thought elemental composition, being cigar tobacco showed differences in relation to shredded and rope tobacco samples.

p. 36–40 Submitted by Santiago Fabio (fabio.ssantiago@hotmail.com) on 2013-10-29T19:46:35Z No. of bitstreams: 1 5555555.pdf: 374813 bytes, checksum: 9e24884b818f84498479904799d6df24 (MD5) Made available in DSpace on 2013-10-29T19:46:35Z (GMT). No. of bitstreams: 1 5555555.pdf: 374813 bytes, checksum: 9e24884b818f84498479904799d6df24 (MD5) Previous issue date: 2013 The present work aims at the determination of silver in airborne particulate matter (APM) collected on glass fiber filters using direct solid sampling and high-resolution continuum source graphite furnace atomic absorption spectrometry. The secondary line at 338.289 nm was used for all measurements. A manual solid sampling accessory and solid sampling platforms were used for sample introduction. A mass of 400 μg of ruthenium was thermally deposited on the platform surface as permanent modifier. The optimum pyrolysis and atomization temperature was 1,000 and 2,000 °C, respectively. Aqueous standard solutions were used for calibration exclusively. The analytical parameters obtained for the proposed method were as follows: characteristic mass, 4.4 pg Ag; detection limit (3σ, n = 10), 17 ng g− 1; and quantification limit (10σ, n = 10), 58 ng g− 1. These limits are equivalent to 0.05 and 0.16 ng m− 3, respectively, for 0.36 mg of sample mass (filter + APM) and an average volume of 1,440 m3 air that had passed through the filter. The certified reference material urban particulate matter, NIST 1648, was used for checking the accuracy. Four filter samples with APM collected in Buenos Aires, Argentina, were analyzed. According to our study, the concentration of silver (average ± confidence interval at 95% level, n = 5) varied between 0.64 ± 0.06 and 1.18 ± 0.07 μg g− 1, corresponding to 1.99 ± 0.11 and 4.54 ± 0.26 ng m− 3. The precision, expressed as relative standard deviation, varied between 1.6 and 7.1% (n = 5). The analytical method proved to be simple, fast and reliable. Highlights ► Determination of Ag in APM sample by HR-CS SS-GFAAS was proposed. ► The proposed method is simple, fast, reliable and suitable for routine applications. ► Procedure of determination of silver in environmental samples avoiding dissolution. ► Solid sampling is environmentally friendly when compared conventional methods. Salvador

This article presents a critical evaluation of the analytical procedures used for the determination of lead in seawater, which is important because lead is a good indicator of marine pollution caused by human activities. Sampling, storage, and pretreatment techniques are briefly overviewed, including the significance of systematic errors that cannot be corrected later on. The main techniques in this article are electrothermal–atomic absorption spectrometry (ET-AAS), inductively coupled plasma–mass spectrometry (ICP-MS), and voltammetry. Flame atomic absorption spectrometry (FAAS) and inductively coupled plasma–optical emission spectrometry (ICP-OES) are treated as well, although their limits of quantification are not sufficient for a determination of lead in unpolluted seawater. Even when separation and preconcentration techniques are applied, these techniques are only capable of detecting lead in polluted coastal seawater. Separation and preconcentration are actually also required for ET-AAS an...

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

A critical evaluation of the determination of uranium by inductively coupled plasma optical emission spectrometry was performed using factorial designs (23) involving the factors: acid concentration, radio frequency power and nebulizer gas flow rate. All of the experiments in this study were made for five emission lines, in the presence of nitric and hydrochloric acid. The results demonstrated that, between nitric and hydrochloric acid, the determinations in the presence of nitric acid were most sensitive. The factorial design showed that the nebulizer gas flow rate was the most significant among the factors studied for the five emission lines. Calcium in concentrations of 10 mg L−1 was observed to cause suppression of the emission intensity for some lines. Iron (at least up to 10 mg L−1) did not interfere in the emission intensity of uranium across the five lines studied. Another experiment evaluated simultaneously the effect of 13 other elements, and the results demonstrated that these elements did not affect the emission intensity of uranium for the lines chosen. The optimized method, using the line at 385.957 nm, allows the determination of uranium with limit of quantification of 31 μg L−1 and precision expressed as RSD lower than 2.2% for uranium concentrations of either 500 or 1000 μg L−1. The accuracy was confirmed by analysis of two laboratory reference materials. The developed method was applied to the determination of uranium in an industrial effluent collected from uranium-producing mine in Caetite City, Brazil. The sample was analyzed by inductively coupled plasma mass spectrometry ICP-MS, and the observed recovery was satisfactory.

A simple and fast method for the determination of Ca, Cd, Co, Cu, Fe, Mn, Mo, Na, Ni, Pb, Rb, Sr, V and Zn in fruit juices samples, by inductively coupled plasma mass spectrometry (ICP-MS) after only a sample dilution, is proposed. For comparison, the samples were also digested with nitric acid and hydrogen peroxide in a microwave oven. The same conditions could be used for aqueous standard solution and diluted sample and the sensitivity was similar in both media, thus external calibration against aqueous standard solutions could be used for quantification. The results were in agreement with those obtained after digestion, according to the t -test at a 95% confidence level. The good accuracy was also confirmed by the recovery test. The precision expressed by the relative standard deviation (RSD) was between 1 and 3%. The detection limits were between 0.1 (Pb) and 2000 μg L −1 (Ca). Similar values for detection limits and RSD were obtained after sample digestion or when the internal standard was not used. The compositions of 20 samples were evaluated by multivariate analysis techniques: principal component analysis (PCA) and hierarchical cluster analysis (HCA), showing that samples are grouped by the brand and not by the fruit, what could be due to soil characteristics where the plant was grown and to the different processing and storage conditions used by the different brands, including water and additives.

Methods for the determination of 5 major (Ca, K, Mg, Na and P) and 14 minor elements (Al, Ba, Cd, Co, Cu, Fe, Ga, Mn, Mo, Ni, Pb, Rb, Sr and Zn) in vegetable seeds by ICP OES and by ICP-MS, respectively, are proposed. After a common sample preparation consisting of smashing and homogenization in an agata mortar, followed by acid digestion in a microwave oven, the diluted sample solutions were measured in the spectrometers using conventional pneumatic nebulizers. External calibration with aqueous standard solutions was used for both techniques. Internal standard was not required, due to the absence of non-spectral interference. For the major elements, the detection limits were in the range of 0.01 (Mg) to 0.3 µg g− 1 (Na and K) and for the minor elements they were in the range of 0.001 (several) to 0.4 µg g− 1 (Fe). The detection limits were adequate for the seed analysis. The accuracy was validated by analyzing a botanical certified reference material (Pine Needles). Agreement of the concentrations with the certified or informed values was obtained, according to the t-test for a confidence level of 95%. The relative standard deviations were below 10% indicating an adequate precision. Seeds from seven different plants were analyzed: cotton seed, sunflower, castor bean, fodder turnip, curcas bean, soybean and tung. The element concentrations varied considerably in the different samples. The results were also evaluated using the principal component analysis.

The development of a homogeneity study during the preparation of a wheat flour laboratory reference material (LRM) for use in the quantification of metals and metalloids is reported. Inductively coupled plasma optical emission spectrometry (ICP OES) was used with validation performed using a certified reference material of wheat flour furnished by the National Institute of Standards and Technology (NIST). Copper, iron, manganese, phosphor, strontium and zinc were studied in a within-bottle homogeneity test whereas barium, copper, iron, zinc, manganese, strontium, phosphor and calcium were included in a between batch homogeneity study. Standard univariate analysis of variance (ANOVA) was performed for all analytes. Furthermore an alternative multivariate analysis for homogeneity is proposed by performing ANOVA of principal component scores and by inspection of principal component score graphs and hierarchical cluster analysis dendrograms. The ANOVA F -tests performed on both, the univariate and multivariate parameters, were not significant at the 95% confidence level and indicated homogeneous wheat flour samples. A 10 kg amount of material was processed, which was distributed in 100 bottles, each containing 100 g. For the between-bottle homogeneity test, three replicates were taken from each of 10 bottles selected of the 100 bottles obtained. The results were evaluated using an F-test , which demonstrated no significant difference for the between-bottle results. It is indicative that this material is homogeneous. Afterwards, the influence of the sample mass on the homogeneity of the material was also evaluated by quantification of the elements for 100, 300, 500, 700 and 1000 mg sample masses with all the experiments being performed in triplicate. The F -test was also used for evaluation of these results and demonstrated that the material is homogeneous for masses taken in the 100 to 1000 mg range. All these results were further evaluated employing the principal component analysis (PCA) and hierarchical cluster analysis (HCA) multivariate techniques. Both techniques also demonstrated that the material is perfectly homogeneous for use as laboratory reference material.

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.