Search

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 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

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.

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.

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

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.

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.

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

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.

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.